CHARACTERIZING GRASS-FED GROUND BEEF AND ENHANCED STEAKS 
USING MODIFIED ATMOSPHERE PACKAGING 
 
 
Except where reference is made to the work of others, the work described in this thesis is 
my own or was done in collaboration with my advisory committee. This thesis does not 
include proprietary or classified information. 
 
 
________________________________________ 
Lillie Marie Sledge 
 
 
 
Certificate of Approval: 
 
_______________________       _______________________ 
Manpreet Singh        Christopher R. Kerth, Chair 
Assistant Professor        Associate Professor  
Poultry Science        Animal Science      
      
 
 
_______________________           _______________________ 
Kyle Willian         George T. Flowers 
Assistant Professor        Interim Dean 
Department of Chemistry       Graduate School 
Tuskegee University 
Tuskegee, Alabama       
 
CHARACTERIZING GRASS-FED GROUND BEEF AND ENHANCED STEAKS 
USING MODIFIED ATMOSPHERE PACKAGING 
 
 
Lillie Marie Sledge 
 
A Thesis 
 Submitted to  
the Graduate Faculty of  
Auburn University  
in Partial Fulfillment of the  
Requirements for the  
Degree of 
Master of Science 
 
Auburn University  
December 19, 2008 
iii 
CHARACTERIZING GRASS-FED GROUND BEEF AND ENHANCED STEAKS 
USING MODIFIED ATMOSPHERE PACKAGING 
 
 
 
Lillie Marie Sledge 
 
Permission is granted to Auburn University to make copies of this thesis at its discretion, 
upon request of individuals or institutions and at their expense.  The author reserves all 
publication rights. 
 
 
 
________________________ 
Signature of Author   
 
  
 
________________________ 
Date of Graduation   
 
iv 
VITA 
 Lillie Marie Sledge, the daughter of Tom and Emily Rogers and Shalon Sledge, 
was born on June 1, 1984 in Florence, Alabama.  Lillie grew up on the family farm (aka 
Noah?s Ark) in Rogersville, Alabama.  In May 2002, Lillie graduated from Lauderdale 
County High School and enrolled at the University of North Alabama.  In July of 2003 
Lillie moved to Auburn to attend Auburn University and graduated in May 2006 with a 
B.S. degree in Animal Sciences Pre-Vet.  The following August Lillie began her Masters 
of Science degree in Animal Science with an emphasis on Meat Science and Muscle 
Biology.  Lillie will graduate in December 2008 with her M. S. degree.  Starting in 
August 2008 she will be attending Auburn University?s College of Veterinary Medicine 
with hopes of pursuing a food animal or public health veterinarian career following 
graduation in May 2012. 
v 
THESIS ABSTRACT 
CHARACTERIZING GRASS-FED GROUND BEEF AND ENHANCED STEAKS 
USING MODIFIED ATMOSPHERE PACKAGING 
 
Lillie Marie Sledge 
Master of Science, December 19, 2008 
(B.S., Auburn University, 2006) 
 
138 Typed Pages 
Directed by Christopher R. Kerth 
 
 Fall-born Angus x Continental crossbred steers (n = 18) were randomly assigned 
to six 1.4 ha paddocks with 3 head in each paddock.  The paddocks had been randomly 
planted with Marshall Ryegrass (Lolium multiflorum L.), Wren?s Abruzzi Rye (Secale 
cereael L.) and Harrison Oats (Avena sativa L.).  Boneless strip loins and ribeyes from 
the left side of the carcass were collected at 48 h postmortem, vacuumed-packaged and 
stored at 2?C until 14 d postmortem.  On d 14 postmortem three 2.54-cm-thick steaks 
were cut from the anterior end of the left strip loin from all 18 carcasses. The strip loins 
and ribeyes were cut in half and the posterior and anterior ends were randomly assigned 
to an injection treatment resulting in 0.6% salt, 0.4% phosphate (BRIFISOL 85 Instant, 
BK Giulini Corporation, Simi Valley, CA), 2.5% potassium lactate (Ultra-Pure PL-85 
vi 
(60%), Trumark Inc., Linden, NJ), and 0.055% beef stock (Proliant Meat Ingredients, 
Ankeny, IA).  They were pumped to a 112% of their green weight and cut into four 2.54-
cm-thick steaks.  Packaging treatments used for this study were a high oxygen (HO; 80% 
O
2
/20% CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon monoxide (CO; 65% 
N
2
/34.6% CO
2
/0.4% CO), and vacuum packaging (VAC).  Results indicated that the 
pumped strip loin steaks showed higher sensory scores for initial and sustained juiciness, 
initial and sustained tenderness, flavor intensity, and off flavor (P < 0.05).  The HO 
resulted with the lowest scores for the sensory characteristics (P < 0.05) except for initial 
juiciness.  Retail visual and instrumental scores were the highest for the CO which 
produced and maintained a bright, cherry-red appearance (P < 0.05) for both the strip 
loins and ribeyes.  TBARS was conducted only on the ribeye steaks which indicated that 
the pumped steaks resulted with the most oxidation and the LO had the least oxidation (P 
< 0.05). 
 Eighteen kilograms of grass-fed beef trim from fall-born Angus x Continental 
crossbred steers and eighteen kilograms of grain-fed beef trim were ground to achieve 
separate batches with approximately 20% fat.   Six titrations were made from each of the 
ground trimmings containing: 0% grass/100% grain (0/100), 20% grass/80% grain 
(20/80), 40% grass/60% grain (40/60), 60% grass/40% grain (60/40), 80% grass/20% 
grain (80/20), and 100% grass/0% (100/0) grain.  Each titration was packaged using a 
high oxygen (HO; 80% O
2
/20% CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon 
monoxide (CO; 65% N
2
/34.6% CO
2
/0.4% CO) or OV (overwrap).   Results showed that 
there was no difference in diet*modified atmosphere packaging (MAP; P > 0.05) for 
vii 
initial and sustained juiciness, cohesiveness, flavor intensity, off flavor, or cookloss.  The 
100/0 titration resulted in better (P < 0.05) instrumental (a*) and visual color scores.  The 
CO package produced and maintained a bright, cherry-red color through out the retail 
display.  TBARS values were the lowest for the titrations with the most grass percentage 
(P < 0.05).   
 
viii 
ACKNOWLEDGEMENTS 
 
 I would like to thank my family and friends for providing unconditional support 
over the past two years.  They have always been there for me when I have least expected.  
I would like to give thanks to my major professor Dr. Chris Kerth for providing me with 
financial support as well as directing me through this project.  A thank you also goes out 
to my other committee members Dr. Manpreet Singh and Dr. Kyle Willian for providing 
support and help when needed.   
 A special thanks goes to Abby Frank Crow for helping me stay focused and sane 
during the past two years.  The other Animal Science graduate students, faculty members 
and meat lab employees, especially Barney Wilborn, Pete Holloway, Clint Rowe and Dr. 
Christy Bratcher, have provided much support and hours and I would not have been able 
to have completed this without their contributions. 
ix 
Style manual or journal used:  Journal of Animal Science 
Computer software used:  Microsoft Word 
x 
TABLE OF CONTENTS 
LIST OF TABLES .......................................................................................................xiv 
LIST OF FIGURES....................................................................................................... xv 
CHAPTER I.  INTRODUCTION....................................................................................1 
CHAPTER II.  REVIEW OF LITERATURE..................................................................4 
Forage-fed Beef...................................................................................................4 
Consumer Demand and Health Benefits...............................................................5 
Lean Color...........................................................................................................6 
Tenderness...........................................................................................................8 
Flavor ................................................................................................................ 10 
Juiciness ............................................................................................................ 12 
Overall Acceptability......................................................................................... 13 
Retail Shelf Life................................................................................................. 14  
Storage .............................................................................................................. 15 
Enhanced Beef................................................................................................... 17 
Conclusion......................................................................................................... 18 
Research Objectives........................................................................................... 18 
CHAPTER III.  CHARACTERIZING GRASS-FED ENHANCED STEAKS USING 
MODIFIED ATMOSPHERE PACKAGING..................................................... 20 
 
Introduction ....................................................................................................... 21 
xi 
Materials and Methods....................................................................................... 24 
Animals and Diet ................................................................................... 24 
Sample Collection and Preparation......................................................... 24 
Initial Color Measurements .................................................................... 25 
Storage and Retail Display ..................................................................... 26 
Retail Color Measurements .................................................................... 26 
Sensory ..................................................................................................27 
Determination of Lipid Oxidative Stability............................................. 27 
Statistical Analysis................................................................................. 28 
Results............................................................................................................... 28 
Initial Color............................................................................................ 28 
Sensory ..................................................................................................31 
Off Flavor ..............................................................................................32 
Retail shelf-life....................................................................................... 32 
Lipid oxidation....................................................................................... 33 
Discussion ......................................................................................................... 33 
Initial Color............................................................................................ 33 
Sensory ..................................................................................................35 
Off Flavor .............................................................................................. 35 
Retail shelf-life....................................................................................... 35 
Lipid oxidation....................................................................................... 36 
Implications ........................................................................................... 36 
Tables .................................................................................................... 37 
xii 
Figures ................................................................................................... 39 
CHAPTER IV.  CHARACTERIZING GRASS-FED GROUND BEEF USING 
MODIFIED ATMOSPHERE PACKAGING .................................................... 70 
  
 Introduction ....................................................................................................... 71 
 
Materials and Methods....................................................................................... 73 
Sample Collection and Preparation......................................................... 73 
Initial and Retail Display Color Measurements....................................... 74 
Storage and Retail Display ..................................................................... 75 
Sensory ..................................................................................................76 
Determination of Lipid Oxidative Stability............................................. 76 
Statistical Analysis................................................................................. 77 
Results............................................................................................................... 78 
Initial Color............................................................................................ 78 
Sensory ..................................................................................................79 
Off Flavor .............................................................................................. 80 
Retail shelf-life....................................................................................... 80 
Lipid oxidation....................................................................................... 81 
Discussion ......................................................................................................... 81 
Initial Color............................................................................................ 81 
Sensory ..................................................................................................81 
Off Flavor .............................................................................................. 82 
Retail shelf-life....................................................................................... 82 
Lipid oxidation....................................................................................... 83 
xiii 
Implications ........................................................................................... 83 
Tables .................................................................................................... 84 
Figures ................................................................................................... 85 
LITERATURE CITED.................................................................................................. 96 
APPENDICES ............................................................................................................ 110 
Appendix A. Retail Display Shelf-Life Visual Evaluation Setup.................................. 111 
Appendix B. Instrumental Color Evaluation ................................................................ 112 
Appendix C. Sensory Evaluation................................................................................. 113 
Appendix D. TBARS .................................................................................................. 114 
Appendix E. Ground Beef Trained Sensory Evaluation Form...................................... 116 
Appendix F. Trained Sensory Evaluation Form ........................................................... 117 
Appendix G. Retail Display Shelf-life Visual Evaluation............................................. 118 
 
 
xiv 
LIST OF TABLES 
 
CHAPTER III 
 
 Table 3.1............................................................................................................ 37 
 Least Square Means ? SEM of Sensory Loin Steaks from four different MAP 
packaging treatments and two pump treatments. 
 
 Table 3.2............................................................................................................ 38 
Incidence of Off flavor descriptors as a percent for striploin steaks for non-
pumped and pumped injection treatments and MAP packages. 
CHAPTER IV 
 Table 4.1............................................................................................................ 84 
Least Square Means ? SEM of Sensory Ground Beef patties from different 
MAP packaging treatments and six grass/grain titrations. 
xv 
LIST OF FIGURES 
 
CHAPTER III 
Figure 3.1 .......................................................................................................... 39 
Least square means ? SEM for CIE L* instrumental values of striploin 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.2 .......................................................................................................... 40 
Least square means ? SEM for CIE a* instrumental values of striploin 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.3 .......................................................................................................... 41 
Least square means ? SEM for CIE b* instrumental values of striploin 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.4 .......................................................................................................... 42 
Least square means ? SEM for CIE Fat L* instrumental values of striploin 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.5 .......................................................................................................... 43 
Least square means ? SEM for CIE Fat a* instrumental values of striploin 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.6 .......................................................................................................... 44 
Least square means ? SEM for CIE Fat b* instrumental values of striploin 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
 
xvi 
Figure 3.7 .......................................................................................................... 45 
Least square means ? SEM for lean Hue instrumental values of striploin 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.8 .......................................................................................................... 46 
Least square means ? SEM for lean Chroma instrumental values of 
striploin steaks by pumped and non-pumped treatments at beginning and 
end of retail display for MAP. 
Figure 3.9 .......................................................................................................... 47 
Least square means ? SEM for lean metmyoglobin instrumental values of 
striploin steaks by pumped and non-pumped treatments at the end of retail 
display for MAP. 
Figure 3.10 ........................................................................................................ 48 
Least square means ? SEM for fat Hue instrumental values of striploin 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.11 ........................................................................................................ 49 
Least square means ? SEM for fat Chroma instrumental values of striploin 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.12 ........................................................................................................ 50 
Least square means ? SEM for visual lean color of striploin steaks by 
retail display day within pumped and non-pumped treatments for MAP. 
Figure 3.13 ........................................................................................................51 
Least square means ? SEM for visual lean uniformity of striploin steaks 
by retail display day within pumped and non-pumped treatments for MAP. 
Figure 3.14 ........................................................................................................ 52 
Least square means ? SEM for visual lean discoloration of striploin steaks 
by retail display day within pumped and non-pumped treatments for MAP. 
 
 
xvii 
Figure 3.15 ........................................................................................................ 53 
Least square means ? SEM for visual lean browning of striploin steaks by 
retail display day within pumped and non-pumped treatments for MAP. 
Figure 3.16 ........................................................................................................ 54 
Least square means ? SEM for thiobarbituric reactive substance values of 
ribeye steaks at the end of retail display by pumped and non-pumped 
treatments for MAP. 
Figure 3.17 ........................................................................................................ 55 
Least square means ? SEM for CIE L* instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.18 ........................................................................................................ 56 
Least square means ? SEM for CIE a* instrumental values of ribeye steaks 
by pumped and non-pumped treatments at beginning and end of retail 
display for MAP. 
Figure 3.19 ........................................................................................................ 57 
Least square means ? SEM for CIE b* instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.20 ........................................................................................................ 58 
Least square means ? SEM for CIE Fat L* instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.21 ........................................................................................................ 59 
Least square means ? SEM for CIE Fat a* instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.22 ........................................................................................................ 60 
Least square means ? SEM for CIE Fat b* instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
 
xviii 
Figure 3.23 ........................................................................................................ 61 
Least square means ? SEM for lean Hue instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.24 ........................................................................................................ 62 
Least square means ? SEM for lean Chroma instrumental values of ribeye 
steaks by pumped and non-pumped treatments at beginning and end of 
retail display for MAP. 
Figure 3.25 ........................................................................................................ 63 
Least square means ? SEM for fat Hue instrumental values of ribeye 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.26 ........................................................................................................ 64 
Least square means ? SEM for fat Chroma instrumental values of ribeye 
steaks by pumped and non-pumped treatments at the end of retail display 
for MAP. 
Figure 3.27 ........................................................................................................ 65 
Least square means ? SEM for lean metmyoglobin instrumental values of 
ribeye steaks by pumped and non-pumped treatments at the end of retail 
display for MAP. 
Figure 3.28 ........................................................................................................ 66 
Least square means ? SEM for visual lean color of ribeye steaks by retail 
display day within pumped and non-pumped treatments for MAP. 
Figure 3.29 ........................................................................................................67 
Least square means ? SEM for visual lean uniformity of ribeye steaks by 
retail display day within pumped and non-pumped treatments for MAP. 
Figure 3.30 ........................................................................................................ 68 
Least square means ? SEM for visual lean discoloration of ribeye steaks 
by retail display day within pumped and non-pumped treatments for MAP. 
 
 
xix 
Figure 3.31 ........................................................................................................ 69 
Least square means ? SEM for visual lean browning of ribeye steaks by 
retail display day within pumped and non-pumped treatments for MAP. 
CHAPTER IV 
 
 Figure 4.1 .......................................................................................................... 85 
  
Least square means ? SEM for ground beef for grassy off descriptor as a 
percent frequency. 
 
 Figure 4.2 .......................................................................................................... 86 
 
Least square means ? SEM for CIE L* instrumental values of ground beef 
by grass/grain titrations at beginning and end of retail display for MAP. 
 
 Figure 4.3 .......................................................................................................... 87 
Least square means ? SEM for CIE a* instrumental values of ground beef 
by grass/grain titrations at beginning and end of retail display for MAP. 
 Figure 4.4 .......................................................................................................... 88 
Least square means ? SEM for CIE b* instrumental values of ground beef 
by grass/grain titrations at beginning and end of retail display for MAP. 
 Figure 4.5 .......................................................................................................... 89 
Least square means ? SEM for metmyoglobin instrumental values of 
ground beef by grass/grain titrations at beginning and end of retail display 
for MAP. 
 Figure 4.6 .......................................................................................................... 90 
Least square means ? SEM for Hue instrumental values of ground beef by 
grass/grain titrations at the beginning and end of retail display for MAP. 
Figure 4.7 .......................................................................................................... 91 
Least square means ? SEM for Chroma instrumental values of ground 
beef by grass/grain titrations at the beginning and end of retail display for 
MAP. 
  
 
xx 
 Figure 4.8 .......................................................................................................... 92 
Least square means ? SEM for visual lean color of ground beef by 
grass/grain titrations at the beginning, middle, and end of retail display for 
MAP. 
 Figure 4.9 .......................................................................................................... 93 
Least square means ? SEM for visual lean discoloration of ground beef by 
grass/grain titrations at the beginning, middle, and end of retail display for 
MAP. 
 Figure 4.10 ........................................................................................................ 94 
Least square means ? SEM for visual lean browning of ground beef by 
grass/grain titrations at the beginning, middle, and end of retail display for 
MAP. 
 Figure 4.11 ........................................................................................................ 95 
Least square means ? SEM for thiobarbituric reactive substance values of 
ground beef at the end of retail display by grass/grain titrations for MAP. 
 
 
 
 
 
 
1 
CHAPTER I 
INTRODUCTION 
 
Forage-fed beef accounted for the majority of beef production and sales in the 
United States prior to World War II (Schupp et al., 1980).  Popularity of forage-fed beef 
declined in the 1950s and 1960s when the large-scale cattle finishing system was 
developed which demanded an increase in grain-based finishing regimens.  Soon 
consumers became accustomed to the characteristics, such as flavor, tenderness, and 
juiciness, which results from high quality, well-marbled grain-fed beef.  During the late 
1970s, consumer health consciousness and demand for ?healthy? foods greatly increased 
due to a shift in the American diet (Schupp et al., 1980; Griebenow et al., 1997).   
Today consumers are still attracted to the promotion of ?healthy? foods.  Because 
of this demand, organic, natural, and grass-fed beef has regained recognition in niche 
markets which seems to follow the demand theory that states that consumers should be 
influenced by the factors related to human health and beef production supplies (Schupp et 
al., 1980).  Many consumers desire a product that is leaner and environmentally friendly 
which is a result from forage-fed systems.  A drive for forage-fed beef production has 
been created by the rapid increase in the world?s human population.  This population 
increase could possibly create a shortage in the supply of grain worldwide, thus creating 
an importance for grass or forage production systems (Reverte et al., 2003).   
2 
 The southeastern United States is a region that has optimum conditions for a year-
round forage production system (Cox, 2004; Sapp et al., 1999).  In the United States, 
consumers demand products that are developed from an array of specialty areas (Braden, 
2006; Resurreccion, 2003) such as forage-finished beef which is now a leading niche 
market (Braden, 2006; Prevatt et al., 2006). Since today?s consumers are interested in 
convenient, heat-and-eat products the beef industry is in competition with the poultry 
industry that already has several convenience products available to consumers.  The beef 
industry has been able to meet consumers? needs by providing them with a safe yet 
flavorful product.   
 To meet the growing demands for beef, the beef industry and researchers have 
been working on improving shelf-life stability and palatability of forage-fed beef to 
provide a longer-lasting product for the niche market.  Since forage?fed beef naturally 
contains more vitamin E than grain-fed beef it is possible that the beef will naturally 
improve oxidative stability, enhance color retention, and increase retail shelf life offering 
an opportunity for ?value added? consumer products with enhanced nutrient value 
according to Decker et al. (2000).  Animals finished on forage diets have been noted to 
provide acceptable carcass weights and degrees of finish when finished at a young age 
(Muir et al., 1998a).  This study also showed that acceptable quality characteristics can 
also be achieved by a forage-finishing system when compared to a grain-based diet.   
 The purpose of the research presented is to study the effects of modified 
atmosphere packaging using high-oxygen, carbon monoxide, and low-oxygen gas 
mixtures with a traditional overwrap as the control and brine injection on forage-fed beef 
as well as the study of modified atmosphere packaging (MAP) on ground beef when 
3 
mixed with grain-fed and forage-fed beef.  Few studies have been done on MAP with 
forage-fed beef and enhancement.  Enhancement of the forage-fed beef as well as a 
specific modified atmosphere packaging system will possibly improve the quality, shelf-
life, and organoleptic characteristics of the meat.  Three different forage treatments were 
also included in this study to determine which forage will benefit the grain-fed meat 
quality characteristics the most.  
 
 
   
4 
 CHAPTER II 
REVIEW OF LITERATURE 
 
Forage-fed Beef 
 The niche market for forage-fed beef is increasing rapidly.  Forage-finishing 
systems have been around for many years.  Countries such as Argentina, Australia, and 
Brazil have always had high quality forage-finishing systems due to abundant forage 
production.  Cattle convert forages, a low-quality food source, into a high-quality food 
source that can be used for human consumption very efficiently (Bidner et al., 1986). The 
cycle for forage-fed beef production typically recurs when grain production is decreased 
(Bowling et al., 1977; Schupp et al., 1980).  Besides the decrease in grain production and 
higher cost for grain products tending to lead to more forage-finishing systems, forage-
fed beef has been known to provide many health benefits such as to prevent heart disease, 
obesity, diabetes, and cancer (Pariza, 1997; Weiss et al., 2004).   According to 
Wanderstock and Miller (1948) grass-fed beef was lower quality, less tender, yellower in 
fat color, and trimmer both externally and internally than traditional grain-fed beef.  
Additionally, others have reported grain-fed beef to be more tender, more flavorful, and 
more palatable than grass-fed beef (Bowling et al., 1977; Kropf et al., 1975).  By using 
appropriate tenderization techniques such as electrical stimulation or blade tenderization, 
5 
it may be possible to make forage-fed beef comparable to grain-fed beef in tenderness 
(Bidner et al., 1985).   
Consumer Demand and Health Benefits  
Consumers have been known to pay more for a product that provides many health 
benefits as well as a product that is environmentally friendly (Moloney, 2001; Tarrant, 
1998).  Forage-fed beef is known to provide many health benefits such as reducing the 
risk of heart disease (Weiss et al., 2004).  Cattle reared on forage are known to contain 
higher amounts of omega-3 fatty acids and a more favorable omega-6 to omega-3 fatty 
acid ratio (French et al., 2000).  Research on forage-fed beef has shown that the meat 
contains high levels of conjugated linoleic acid (CLA), poly-unsaturated and omega-3 
fatty acids, and a higher ratio of unsaturated fatty acids to saturated fatty acids (Mitchell 
et al., 1991; Mandell et al., 1997; and French et al., 2001).  Forage-fed beef has superior 
fatty acid composition when compared to the traditional grain-fed beef.  Pathogenic 
organisms such as E. coli (Callaway et al., 2003) that are found in the GI tract of meat 
animals is lower in forage-fed animals therefore providing a smaller threat to food 
contamination (Keen et al., 1999).  Forage-fed diets create conditions in the GI tract that 
results in decreased shedding of pathogenic organisms (Johnsson et al., 2001).  
Consumers are tending to focus more on food safety rather than being concerned about 
their nutritional diet (Schafer et al., 1993).   
Many consumers believe highly in the animal welfare act (Bennett, 1996).  The 
animal welfare act has always scrutinized the way the U.S. produces meat animals.  
Perceptions that these production (feed lot) and harvest or slaughter systems are 
inhumane have caused many consumers to refrain from purchasing meat products 
6 
(Harper and Makatouni, 2002).  Since the ?natural?, ?organic?, and many other specialty 
production systems are becoming more popular, many consumers may increase their 
purchase of beef because of labeling forage-fed beef as ?pasture-fed beef? (Harper and 
Makatouni, 2002; Prevatt et al., 2006). 
Lean Color  
 Myoglobin is the basic color pigment for meat.  Deoxymyoglobin is the more 
specific state for myoglobin when there is no oxygen bound to the myoglobin complex, 
therefore the meat is a dark red/ purple color (Aberle et al., 2001).  When meat is exposed 
to oxygen, the myoglobin is oxygenated to form an oxymyoglobin pigment which is best 
described as a bright, cherry-red color.  This bright, cherry-red color is associated with 
the ?freshness? of the meat and it is what consumers are attracted to (Muir et al., 1998a). 
As the meat remains exposed to low partial pressures of oxygen, the myoglobin oxidizes 
and forms an unattractive brown color known as metmyoglobin.  The formation of 
metmyoglobin is affected by chemical changes in the muscle such as the pH level and 
postmortem decline, as well as the content of oxygen that is present within the muscle 
post-mortem (Renerre and Labas, 1987).  The level of pigmentation and the percentages 
of myoglobin, oxymyoglobin and metmyoglobin formation in the muscle ultimately 
determine the meat color.  Consumers perceive discolored meat as unwholesome, un-
fresh, or from older cattle (Muir et al., 1998a).  Two factors must be considered when 
analyzing fresh meat lean color: surface color of the fresh meat and rate of discoloration 
caused by metmyoglobin formation over time.   
 The bright, cherry-red lean color is typical for young grain-fed cattle.  Older 
animals and animals that have been stressed often have a darker lean color.  Lean color is 
7 
influenced by the glycogen stores in the muscle that allow the pH of the muscle to 
decrease post-mortem.  Thompson (2002) reported that a minimum of 57 .notdef.g0001mol/g of 
glycogen is necessary for the pH of muscle to reach the ultimate level of 5.5 in post-
mortem muscle.  Meat with a dark color, typically known as dark cutting or dark firm dry 
(DFD), results when the ultimate pH has elevated due to the glycogen reserves depleting 
below this threshold.  The meat may become less juicy, lack visual appeal, and have 
reduced shelf life due to the increase in the ultimate pH (Thompson, 2002).  
 According to Muir et al. (1998a) production factors and stress are two important 
factors that may influence glycogen in the muscle at time of slaughter therefore resulting 
in a darker lean color due to reduced pH decline.  Muir et al. (1998a) states that in several 
studies comparing forage-finished and grain-finished cattle there were no differences 
found in lean color.  French et al. (2001) and Mandell et al. (1997) support this by 
reporting similarities in lean color of forage-finished and concentrate-finished cattle.  
Differences have been found by other researchers in lean color between feeding 
regiments; forage-finished cattle were found to have a darker lean color than grain-fed 
cattle (Bennett et al., 1995; Bidner et al., 1986; Schroeder et al., 1980).  Bidner et al. 
(1986) stated that a higher myoglobin concentration is linked to the darker lean color that 
is seen in forage-fed beef.  Grass-fed steers have a higher ultimate pH than grain-fed 
steers according to Muir et al. (1998b).  Since grass-fed steers are known to have higher 
ultimate pH values, researchers believe the increased pH is because grass-fed steers were 
more susceptible to pre-slaughter stress and therefore they would suffer glycogen 
depletion in the factory pre-slaughter process (Muir et al., 1998b).  A higher pH value is 
correlated to a darker lean or muscle tissue.  Research has been conducted to possibly 
8 
link a type of forage with an outcome on lean color.  A study by Schaake et al. (1993) 
reported that there is no difference in animals reared on a spring fescue-clover pasture 
when compared to animals that are finished in a drylot, but in this study the cattle on 
summer pastures produced a darker lean color.   
Tenderness 
 According to consumer studies, tenderness is considered the most important 
contributor to the eating quality of meat (Maltin et al., 2003).  The muscle and collagen 
or connective tissue components are known to be the major two influences on meat 
tenderness (Koohmaraie, 1992).  During the aging process of the carcass post-mortem, 
the muscle or myofibrillar proteins are often degraded by proteolytic enzymes (especially 
calpains) and appears to affect tenderness more than the pre-slaughter characteristics of 
collagen or connective tissue (Koohmaraie, 1992).  According to McIntyre and Ryan 
(1984), there have been no differences in the shear force values or taste panel assessment 
of beef tenderness when grain-fed cattle and grass-fed cattle grew at a similar rate prior to 
harvest at the same age and weight.  Mitchell et al. (1991) stated that from the 10 grain-
fed and 10 forage-fed carcasses the steaks from the grain-fed carcasses were more tender 
and more flavorsome than the forage-fed steaks. 
 Forage-fed animals are finished at an older chronological age that grain-fed 
animals (Bowling, 1978).  Finishing requires more time on forage to achieve desired 
weight gain; therefore forage-finished cattle have a slower weight gain than grain-
finished cattle (Muir et al., 1998a).  The age of the animal at slaughter, growth rate, and 
chilling rate are all interrelated and seem to be factors that are influential on the 
tenderness of forage-finished beef.  Aberle et al. (2001) states that as the animal ages, the 
9 
cross-links between collagen increases and becomes less soluble.  Forage-finished cattle 
seem to have little to no difference on tenderness values overall when compared to 
tenderness values of grain-fed cattle, when comparing both finishing systems at the same 
weight and fat thickness.  Cox et al. (2006) found no difference in insoluble or soluble 
collagen based on finishing-diets. 
 Thompson (2002) states that tenderness is also a function of processing, 
production, value-adding and cooking methods used in meat preparation for consumer 
consumption.  The risk of a poor eating experience for the consumer increases when one 
or more of these links in the beef supply chain fails. Consumers are willing to pay a 
greater price for meat that is guaranteed to be more tender (Boleman et al., 1997).  In 
literature by Simone et al. (1958), Bowling et al. (1977, 1978), and Miller et al. (1987), 
all have commented that there is a distinct positive correlation with meat tenderness and 
carcass fat thickness.  Despite lower fat cover, Hedrick et al. (1983) found that meat from 
cattle finished on silage was just as tender or more tender than grain-fed cattle.  Bowling 
et al. (1977) discovered differences in cooling rates of identical carcasses within chillers.  
This statement then lead to the conclusion that cooling rate differences may only be 
partly responsible for tenderness differences that are shown in grain- and forage-finished 
cattle.  The connection between fat thickness and meat tenderness in carcasses is 
evidentially responsible partly by the chilling rate (Muir et al., 1998a).   
 In a study by Smith et al. (1979) several methods were analyzed to possibly 
improve the tenderness of forage-finished beef.  Methods tested singularly and 
collectively for tenderization included electrical stimulation, delayed chilling, pelvic 
suspension of sides, cooler aging, and blade tenderization of wholesale loins and top 
10 
rounds of forage-finished beef carcasses. Maximum tenderization values of the 
longissimus muscle was by electrical stimulation or delayed chilling of the sides followed 
by blade tenderization or cooler aging of shortloins.  When the initial treatments were 
combined and followed by blade tenderization; tenderness was increased as well as 
decreasing the shear force of the top round steaks, but when treatments where used 
individually, they showed no affect on the semimembranosus muscle. 
 Blade tenderization, electrical stimulation, and vacuum-aging was used by Bidner 
et al. (1981a, 1985) to study forage-finished beef tenderization.  The Warner-Bratzler 
shear force was significantly improved by electrical stimulation but showed no difference 
on the palatability.  Positive effects were shown by the blade tenderization and vacuum-
aging on improving shear force and tenderization values conducted by a taste panel in 
conjunction with the amount of connective tissue.  In this study the most benefits for 
improving tenderness was by combining treatments.  Steaks that were both electrically 
stimulated and either blade-tenderized or vacuum-aged resulted to be more tender than 
steaks that received only one method of treatment.   
Flavor   
 When comparing forage-fed cattle and grain-fed cattle, forage-fed cattle are 
known to have a less desirable flavor than cattle finished on grain (Wanderstock and 
Miller, 1948; Kropf et al., 1975; Bowling et al., 1977).  The less desired flavor of grass-
fed beef is linked to two factors: a lower fat content (Moody, 1976; Harrison et al., 1978) 
and the fatty acid composition (Brown et al., 1979; Westerling and Hedrick, 1979).  The 
characteristic flavor of beef can be influenced by the fat composition (Bagley and Feazel, 
1987) and is dependent on species of animal (Field et al., 1978).  In a study by Melton in 
11 
1983, steers on pasture grasses and bermudagrass pellets had a less desirable or less 
intense beefy flavor when compared to high-energy-fed steers.  Melton (1983) also stated 
that the largest difference in flavor was found between the steers harvested directly off 
grass pasture and from steers finished with a high-energy diet.  This difference in the 
diets is correlated with differences in animal fatness.  Owens and Gardner (1999) state 
that as the fat content increases, the flavor desirability and flavor intensity increases as 
well. 
Since fat is known to store the aromatic compounds for beef flavor (Young and 
Baumeister, 1999), certain chemical changes in the fatty acid composition of forage-fed 
beef will contribute to a potent aroma during cooking (Melton, 1990).  Forage-fed cattle 
have naturally high levels of .notdef.g0001-linolenic acid (18:3) and long chain n-3 polyunsaturated 
fatty acids (PUFA)  which impact flavor by producing a grass-fed taste (Wood et al., 
2003).  The products formed from the oxidation of linolenic acid and its derivatives that 
are derived from grass-feeding give meat from cattle a pastoral flavor (Priolo et al., 
2001).  Several researchers have noted that flavors and aromas in cooked forage-fed beef 
tend to be milky, grassy, cowy, fishy, painty, bloody, livery, medicinal, cardboard, sour, 
and soapy (Moloney et al., 2001; Stika et al., 2007). 
 Forage-fed cattle are known to have a more yellow fat color (Wanderstock and 
Miller, 1948) which is affected by the fatty acid content (Wood et al., 2003).  According 
to Dikeman (1990), a yellower fat color is associated with an older or diseased animal by 
consumers, therefore making it undesirable (Yang et al., 1993).  The diet the animal is 
receiving as well as the animal?s age, sex, and genotype are all factors that can affect the 
12 
fat color which in turn affects the flavor (Pearson, 1966; Morgan and Everitt, 1969; 
Walker et al., 1990).    
 Mandell et al. (1997) used 108 Charolais cross steers to study the effects of 
forage- versus grain-feeding systems on palatability of the beef as well as the carcass 
composition at a specified back fat thickness (4, 7,or 10 mm).  The type of diet did not 
significantly influence the palatability, but forage-fed steers resulted in slightly less beef 
flavor and more off flavor than the grain-fed steers.  Mandell et al. (1997) concluded that 
the differences in flavor may be related to the diet since the forage-fed steers had higher 
linolenic acid concentrations and lower oleic acid concentrations.  This study agreed with 
Cross et al. (1978) where forage had significant effects on fat color, quality grade, and 
amount of marbling which all contribute to the flavor of the meat.  Cross et al. (1978) 
also stated that steers fed ground alfalfa and orchardgrass hay produced a more tender, 
juicy, and intense flavor; when steers fed orchardgrass pasture resulted in less tender, less 
juicy, and detectable connective tissue when assessed by panelists.  Therefore the type of 
grass consumed by the steers does influence the meat quality.   
Juiciness 
 Juiciness is commonly associated with the amount of moisture released and 
degree of salivation during chewing or mastication (Lawrie, 2006).  There are two 
organoleptic parameters that are associated with juiciness in cooked meat.  The first is the 
initial juiciness that is associated with the amount of wetness from the first few chews; 
the second is the sustained juiciness that is associated with the amount of salivation that 
is produced due to the stimulatory effect of fat (Lawrie, 2006).  Forage-fed beef is noted 
by several researchers to have lower juiciness scores when compared to grain-fed beef 
13 
(Hedrick et al., 1983; Sapp et al., 1999).  There are several researchers such as Cross et 
al. (1978) and Bidner et al. (1981b) that reported no differences in juiciness between the 
two feeding systems.  Muir et al. (1998a) reported that the increased amount of juiciness 
in the grain-fed cattle versus the forage-fed cattle was due to the differences in growth 
rate and/or fat covering.  Higher fat covering or higher quality meat produces a more 
juicy product than low quality meat because of the amount of intramuscular fat content 
(Lawrie, 2006).   However, in the study by French et al. (2001), both intra-muscular fat 
content and carcass growth correlated poorly with juiciness for carcasses associated with 
a grass diet.  High-temperature chilling and blade tenderization of forage-fed beef has 
resulted in a less juicy product (Bowling et al., 1977; Bidner et al., 1981a).   
Overall Acceptability 
 In a study conducted by Cox et al. (2006) consumers participating in a retail study 
and a take home study, one-third to one-half of consumers preferred forage-fed beef over 
grain-fed beef across three southeastern states: Alabama, Tennessee, and Kentucky.  
Among the three states, 34.1% of the retail consumers and 54% of the take-home 
consumers preferred forage-fed steaks.  Approximately one-third of the consumers 
preferred the taste of forage-fed beef and was willing to pay a premium.  This data 
supports Umberger et al. (2002) statements of 20% of consumers surveyed in their study 
conducted in Chicago and San Francisco preferred Argentine, forage-finished beef to 
traditional American, grain-finished beef.  This study as well as the study of Cox et al. 
(2006) has showed that the geographical region (three southeastern states, Chicago and 
San Francisco) can have an influence on the acceptability of the forage-finishing system.  
A study conducted by Kerth et al. (2007) showed that 20% of consumers surveyed in 
14 
their study preferred grass-fed beef and were willing to pay a premium; therefore a niche 
market could possibly be an alternative to current production and marketing methods.   
Retail Shelf Life  
 Color has been noted to be the most important factor associated with meat quality 
from a consumer?s perspective.  To extend the shelf-life of the meat products, researchers 
have been analyzing several methods such as type of diet and packaging systems to 
increase the shelf-life of the product.  Since the bright, cherry-red appearance is 
associated with a good quality and healthy product, researchers such as C. O. Gill believe 
that preservative packaging for raw meats must be able to delay both the color 
deterioration and retard bacterial spoilage (Gill, 1996).  Diets containing high levels of 
vitamin E and low amounts of intramuscular fat, such as forage-fed diets, have resulted in 
better maintenance of color and lipid oxidation when compared to grain-fed animals 
(O?Sullivan et al., 2003). 
 Packaging systems such as a modified atmosphere have been noted also to help 
improve shelf-life stability (Gill, 1996; O?Sullivan et al., 2003; Sorheim et al., 1999).  
Even though the animal?s forage diet and modified atmosphere packaging improves color 
and oxidation rates, color depletion and oxidation will eventually occur as the days in the 
retail display continue (Sorheim et al., 1999). 
 Gill (1996) explains that controlling the formation of brown metmyoglobin 
formation on the muscle surface can be slowed by using atmospheres that are rich in 
oxygen or prevented by using an oxygen-depleted atmosphere.  Packaging atmospheres 
high in carbon dioxide or under anaerobic conditions retard bacterial spoilage as long as 
15 
temperatures are maintained at the optimum for chilled storage as well as pre-packaging 
hygienic conditions are noted (Gill, 1996).   
 The rate of oxidation for deoxymyoglobin is more rapid than the rate of oxidation 
for oxymyoglobin (Robach and Pierson, 1979) resulting in faster oxidation of myoglobin 
at low concentrations of oxygen than at high oxygen concentrations (O? Keeffe and 
Hood, 1982).  There are two ways to preserve muscle color apart from retarding pigment 
oxidation by maintaining a low temperature environment; they are by exposing the meat 
to high concentrations of oxygen and largely, or completely, excluding oxygen from the 
meat which results in the increase of the fraction of oxidation-resistant oxymyoglobin 
(Renerre, 1990).  According the Millar et al. (1994), high oxygen atmospheres are used 
mainly for retail-ready products.  Use of high-oxygen atmospheres is usually 
inappropriate for poultry due to their limited ability to bloom (Millar et al., 1994). 
 Storage  
Modified atmosphere packaging (MAP) is one of the newest technologies for 
packaging systems today.  There are several different modified atmospheres that are used 
individually and in combinations that promote the benefits of the individual product 
(Sorheim et al., 1999).  The most important properties to consider when packaging a 
product are a gas mixture that will retard microbial growth, stabilize the product?s color, 
and a gas that is used as a filler (Gill, 1996; Sorheim et al., 1999).  The gases used most 
commonly are carbon dioxide, oxygen and nitrogen.  Carbon dioxide limits the microbial 
growth within the package, oxygen stabilizes the products color but it is known to 
contribute to microbe growth, and nitrogen is the filler gas (Gill, 1996).  The most 
common MAP packaging treatments in the industry for retail-ready systems is high 
16 
oxygen (70% O ) and carbon dioxide (30% CO ; Gill, 1996; O? Sullivan et al., 2002; 
Hunt et al., 2004).   
There are several advantages and disadvantages to this system.  Advantages 
include promoting the desired product color that consumers accept as the preferred meat 
color which is a bright, cherry-red for red meats and creating head space over the product 
which assists in preventing the product from collapsing (Gill, 1996).  Disadvantages to 
the system also occur, such as requiring more storage space for the larger packages; 
therefore not increasing the shelf-life of the product.  Since the high oxygen system is not 
stable due to property changes within the gases the CO  concentration remains relatively 
stable but the O  concentration will decrease and the N  concentration will increase 
progressively over time therefore leakers may be difficult to identify and monitor (Gill, 
1996; Monahan, 2000).   
The use of high oxygen gas (80% O  and 20% CO ) is known to extend shelf-
life for red meats because the high content of oxygen supports the formation of 
oxymyoglobin, while microbial growth is retarded by the carbon dioxide content 
(O?Sullivan et al., 2002).  Reports by Monahan (2000) showed that some high-oxygen 
packaging can promote oxidation and adversely affect color, but with the advantages of 
forage-fed beef the natural Vitamin E content has been researched to delay lipid and 
pigment oxidation therefore resulting in an extended shelf-life (Houben et al., 2000; 
Kerry et al., 2000; O?Sullivan et al., 2002) 
 The use of carbon monoxide was approved by the U. S. Food and Drug 
Administration in 2002 with ?generally recognized as safe? (GRAS) status for packaging 
as long as the meat was removed from the CO atmosphere prior to retail display and sale 
17 
(USFDA, 2002).  Since myoglobin has a high affinity for the CO gas, it creates a bright, 
cherry-red color and is used in muscles that are known to discolor easily (Hunt et al., 
2004).  Norway has been using the CO system for several years because the shelf-life and 
color stability has been increased by the 0.4% CO gas mixture (Sorheim et al., 1999).  
This packaging system accounts for a 50-60% share of the domestic, retail, red meat 
market.  Based on a toxicological, hygienic, and technological standpoint, the use of CO 
up to a 1% concentration does not present any toxic hazards to the consumer (Sorheim et 
al., 1997), but at the same time the CO may mask spoilage because the stable bright red 
color has been noted to outlast the microbiological shelf-life of the meat product (Kropf, 
1980). 
Enhanced Beef 
 In a study by Stika et al. (2007), trimmings from nine mature cows were 
reconstructed into steaks.  The steaks were formulated with a beefy flavoring agent or in 
combination with propyl gallate to promote palatability and stabilization over a six month 
frozen storage period.  The propyl gallate reduced the lipid oxidation, rancidity, and loss 
of beef flavor in the restructured steaks.  By adding the beefy flavoring agent, the mature, 
forage-fed beef off-flavors were masked, beefy flavor was intensified and the tenderness, 
juiciness, and cook yields of the steaks were improved (Stika et al., 2007).  The study by 
Robbins et al. (2003a) agreed that enhanced steaks were more acceptable than non-
enhanced steaks for juiciness and tenderness.  A study by Pietrasik et al. (2006) showed 
that injected steaks containing salt and/or phosphate improved the color stability during 
retail display.  In contrast, studies by Robbins et al. (2003b) and Jensen et al. (2003) have 
reported that color stability of beef and pork is decreased during retail display due to the 
18 
enhancement with a salt or phosphate.  Steaks supplemented with vitamin E were less 
discolored indicating that the vitamin E may improve color short term (up to 2 d retail 
display) on beef enhanced with a salt/phosphate solution (Robbins et al., 2003b). 
 The use of enhancement systems has been proven by several researchers, and for 
consecutive years (Robbins et al., 2002, 2003b), to improve juiciness and tenderness as 
well as improving flavor,  but the use of salt and phosphate solutions has shown a 
negative attribute on shelf life (Robbins et al., 2002, 2003b; Stika et al., 2007).   
Conclusion 
 In conclusion, forage-fed animals are great convertors of cellulose into products 
for human consumption (Bagley and Feazel, 1987) as well as providing health benefits 
associated with the meat such as prevention against heart disease, obesity, diabetes, and 
cancer (Pariza, 1997; Weiss et al., 2004).  Since consumers are demanding a more 
convenient and healthy product researchers, producers, and industry have to step up and 
meet this demand while at the same time produce a product with a good shelf life and 
meat quality characteristics.  The use of MAP and enhancement will possibly provide 
many areas for improving forage-fed beef systems.  Improving quality is essential since 
forage-fed beef contains some negative characteristics such as a yellower fat 
(Wanderstock and Miller, 1948) and off-flavors (Moloney et al., 2001; Stika et al., 2007) 
when compared with grain-fed cattle.  
Research Objectives 
 The purpose of the research presented is to study the effects of modified 
atmosphere packaging using high-oxygen, carbon monoxide, and low-oxygen gas 
mixtures with a traditional overwrap as the control and brine injection on forage-fed beef 
19 
as well as the study of modified atmosphere packaging on ground beef when mixed with 
grain-fed and forage-fed beef.  Few studies have been done on MAP with forage-fed beef 
and enhancement.  Enhancement of the forage-fed beef as well as a specific modified 
atmosphere packaging system will possibly improve the quality, shelf-life, and 
organoleptic characteristics of the meat.  Three different forage treatments were also 
included in this study to determine which forage will benefit the meat quality 
characteristics the most.  
  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
20 
CHAPTER III 
 
CHARACTERIZING GRASS-FED ENHANCED STEAKS USING MODIFIED 
ATMOSPHERE PACKAGING 
 
ABSTRACT 
 Fall-born Angus x Continental crossbred steers (n = 18) were randomly assigned 
to six 1.4 ha paddocks with 3 head in each paddock.  The paddocks had been randomly 
planted with Marshall Ryegrass (Lolium multiflorum L.), Wren?s Abruzzi Rye (Secale 
cereael L.) and Harrison Oats (Avena sativa L.).  Boneless striploins and ribeyes from the 
left side of the carcass were collected at 48 h postmortem, vacuumed-packaged and 
stored at 2?C until 14 d postmortem.  On d 14 postmortem three 2.54-cm-thick steaks 
were cut from the anterior end of the left striploin from all 18 carcasses. The striploins 
and ribeyes were cut in half and the posterior and anterior ends were randomly assigned 
to an injection treatment resulting in 0.6% salt, 0.4% phosphate (BRIFISOL 85 Instant, 
BK Giulini Corporation, Simi Valley, CA), 2.5% potassium lactate (Ultra-Pure PL-85 
(60%), Trumark Inc., Linden, NJ), and 0.055% beef stock (Proliant Meat Ingredients, 
Ankeny, IA).  They were pumped to 112% of their green weight and cut into four 2.54-
cm-thick steaks.   
21 
Packaging treatments used for this study were a high oxygen (HO; 80% O
2
/20% 
CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon monoxide (CO; 65% N
2
/34.6% 
CO
2
/0.4% CO), and vacuum packaging.  Results indicated that the pumped striploin 
steaks showed higher sensory scores for initial and sustained juiciness, initial and 
sustained tenderness, flavor intensity, and off flavor (P < 0.05).  The HO resulted with the 
lowest scores for the sensory characteristics (P < 0.05) except for initial juiciness.  Retail 
visual and instrumental scores were the highest for the CO which produced and 
maintained a bright, cherry-red appearance (P < 0.05) for both the striploins and ribeyes.  
TBARS on the ribeye steaks indicated that the pumped steaks resulted in the most 
oxidation and the LO had the least oxidation (P < 0.05). 
INTRODUCTION 
Forage-fed beef accounted for the majority of beef production and sales in the 
United States prior to World War II (Schupp et al., 1980).  Popularity of forage-fed beef 
declined in the 1950s and 1960s when the large-scale cattle finishing system was 
developed which demanded an increase in grain-based finishing regimens.  Soon 
consumers became accustomed to the characteristics, such as flavor, tenderness, and 
juiciness, which results from high quality, well-marbled grain-fed beef.  During the late 
1970s, consumer health consciousness and demand for ?healthy? foods greatly increased 
due to a shift in the American diet (Schupp et al., 1980; Griebenow et al., 1997).   
Today consumers are still attracted to the promotion of ?healthy? foods.  Because 
of this demand, organic, natural, and grass-fed beef has regained recognition in niche 
markets which seems to follow the demand theory which states that consumers should be 
influenced by the factors related to human health and beef production supplies (Schupp et 
22 
al., 1980).  Many consumers desire a product that is leaner and environmentally friendly 
which is a result from forage-fed systems.  A drive for forage-fed beef production has 
been created by the rapid increase in the world?s human population.  This population 
increase could possibly create a shortage in the supply of grain worldwide, thus creating 
an importance for grass or forage production systems (Reverte et al., 2003).   
 The southeastern United States is a region that has optimum conditions for a year-
round forage production system (Cox, 2004; Sapp et al., 1999).  In the United States, 
consumers demand products that are developed from an array of specialty areas (Braden, 
2006; Resurreccion, 2003) such as forage-finished beef which is now a leading niche 
market (Braden, 2006; Prevatt et al., 2006). Since today?s consumers are interested in 
convenient, heat-and-eat products the beef industry is in competition with the poultry 
industry that already has several convenience products available to consumers.  The beef 
industry has been able to meet consumers? needs by providing them with a safe yet 
flavorful product.   
 To meet the growing demands for beef, the beef industry and researchers have 
been working on improving shelf-life stability and palatability of forage-fed beef to 
provide a longer-lasting product for the niche market.  Since forage?fed beef naturally 
contains more vitamin E than grain-fed beef it is possible that the beef will naturally 
improve oxidative stability, enhance color retention, and increase retail shelf life offering 
an opportunity for ?value added? consumer products with enhanced nutrient value 
according to Decker et al. (2000).  Animals finished on forage diets have been noted to 
provide acceptable carcass weights and degrees of finish when finished at a young age 
23 
(Muir et al., 1998a).  This study also showed that acceptable quality characteristics can be 
achieved by a forage-finishing system when compared to a grain-based diet.   
 Several studies have been conducted on forage-fed beef.  Some researchers have 
stated that forage-fed beef is known to improve the color stability of the product (Arnold 
et al., 1992).  A problem faced with forage-fed beef is that the beef has several off flavors 
such as grassy, rancid, livery, and metallic.  Enhancing forage-fed beef with a beef 
flavoring agent in a salt/phosphate solution has been noted to decrease the intensity of the 
off flavors produced by the forage-fed beef. 
Modified atmospheres are being used more widely to assist in the shelf-life of the 
product.  Atmospheres that promote the blooming of color pigments may not always be 
safe because consumers determine meat quality based on color.  According to Zhao et al. 
(1994) lipid oxidation has been noted to occur at a slower rate than the deterioration of 
the color pigments.  An elevated oxygen level is known to extend color stability, but the 
increased rate of oxidation can also be expected (Zhao et al, 1994).  In the CO packaging, 
a pigment known as carboxymyoglobin is formed.  The carboxymyoglobin is similar to 
the bright red oxymyoglobin pigment that is formed at the surface of fresh meat in air.  
Carboxymyoglobin is known to less readily oxidize to brown metmyoglobin than is 
oxymyoglobin because of the strong binding of CO to the iron site on the myoglobin 
molecule (Lanier et al., 1978).  Results from Sorheim et al. (1999) state that a low 
CO/high CO
2
 atmosphere is effective for preserving retail-retail meats. 
 The purpose of the research presented is to study the effects of modified 
atmosphere packaging using high-oxygen, carbon monoxide, and low-oxygen gas 
mixtures with a traditional overwrap as the control and brine injection on forage-fed beef. 
24 
Few studies have been done on MAP with forage-fed beef and enhancement.  
Enhancement of the forage-fed beef as well as a specific modified atmosphere packaging 
system will possibly improve the quality, shelf-life, and organoleptic characteristics of 
the meat.  Three different forage treatments were also included in this study to determine 
which forage will benefit the meat quality characteristics the most.  
MATERIALS AND METHODS 
Animals and Diet 
 Fall-born Angus x Continental crossbred steers (n = 18) from the Wiregrass 
Research and Extension Center in Headland, Alabama were randomly assigned to six 1.4 
ha paddocks with 3 head in each paddock.  The paddocks had been randomly planted 
with Marshall Ryegrass (Lolium multiflorum L.), Wren?s Abruzzi Rye (Secale cereael L.) 
and Harrison Oats (Avena sativa L.) ryegrass (Lolium perenne).  Two paddocks were 
assigned for each of the forages.  Grazing began in December 2006 and animals were 
humanely harvested on May 1
 
and May 8
 
of 2007 at the Auburn University Lambert-
Powell Meats Laboratory. 
Sample Collection and Preparation 
 Boneless striploins and ribeyes from the left side of the carcass were collected at 
48 h postmortem, vacuum-packaged and stored at 2?C until 14 d postmortem.  On d 14 
postmortem three 2.54-cm-thick steaks were cut from the anterior end of the left striploin 
from all 18 carcasses. The three steaks in order were assigned to fatty acid, sensory, and 
WBS analyses (not discussed in this review). The remaining striploins and ribeyes were 
cut in half and the posterior and anterior ends were randomly assigned to an injection 
(112% of green weight; PUMP) treatment resulting in 0.6% salt, 0.4% phosphate 
25 
(BRIFISOL 85 Instant, BK Giulini Corporation, Simi Valley, CA), 2.5% potassium 
lactate (Ultra-Pure PL-85 (60%), Trumark Inc., Linden, NJ), and 0.055% beef stock 
(Proliant Meat Ingredients, Ankeny, IA) in final product.  A multi-needle pickle injector 
(Gunther Model Typ PI 21, Dieburg, Germany) was used to inject the brine into the 
muscle.  The ends that were to receive the injection treatment were placed aside to have 
green weight recorded prior to receiving the brine injection. After the ends were injected 
and weighed they were cut into four 2.54-cm-thick steaks and then randomly assigned a 
packaging treatment. 
Packaging treatments used for this study were a high oxygen (HO; 80% O
2
/20% 
CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon monoxide (CO; 65% N
2
/34.6% 
CO
2
/0.4% CO), and vacuum (VAC) packaging.  The modified atmosphere packages were 
packaged using a Koch ILPRA FoodPack (Model 400V/G, Corso Pavia, Italy).  A 
Cryovac T7225B Laminate (Duncan, SC) film was used to seal the lids of the trays.  The 
film possessed an oxygen transmission rate of 0.3cc/100 in
2 
/day.   
Initial Color Measurements 
 Following a 48 h postmortem chill, Commission Internationale de l?Eclairage 
(CIE) lean and external fat L* (muscle lightness), a* (muscle redness), and b* (muscle 
yellowness) for the initial color measurements before packaging for the striploins and 
ribeyes were evaluated by utilizing the Hunter Miniscan XE Plus (Hunter Laboratories 
Model 45/0-L, Reston, VA) with a illuminant D65 at a 10? observation angle and a 3.5-
cm aperture.  Reflectance spectra values for the initial lean color were also determined.  
Spectral reflectance values were determined at 520-, 530-, 570-, and 580-nm and 
interpolated to determine the values for 525-nm and 575-nm respectively.  Readings for 
26 
L*, a*, b*, 525 nm and 575 nm reflectance values for lean color were taken from two 
readings on the anterior face of the ribeye and striploin steaks and averaged to obtain a 
representation of the initial lean color. 
Storage and Retail Display 
 Steaks were stored for 21 d in dark storage at 2?C until placed on retail display for 
panel analysis.  Steaks were checked 48 h after packaging and noted for leakers.  After 21 
d dark storage, steaks were placed in a Tyler (Model DMG-8, Niles, MI) retail display 
case at 2?C for retail panel analysis for 5 d.  The illumination intensity was 800lx at the 
surface of the steak, utilizing Sylvania
?
 Designer Cool White Plus bulbs (F40/DCWP).  
Every day, six trained panelists rated the ribeye and striploin steaks for color, uniformity, 
surface discoloration and browning.  Color was based on an 8 point hedonic scale; 1 
equaling extremely dark red and 8 equaling extremely bright cherry-red.  Uniformity was 
based on a 5 point hedonic scale; 1 equaling uniform and 5 equaling extreme two toning.  
A 7 point hedonic scale was used for surface discoloration; 1 equaling zero percent 
discoloration and 7 equaling 100 percent discoloration on surface.  Browning was based 
on a 5 point hedonic scale; 1 equaling none and 5 equaling dark brown.   
Retail Color Measurements 
 Post retail color measurements were taken on d 5 of the display for lean muscle 
and fat color (L*, a* and b*) and lean reflectance values at 520, 530, 570, and 580.  Hue 
angles and saturation index (chroma) values were appropriately using the a* and b* 
values.  Readings for lean color were taken from two readings on the anterior face of the 
ribeye and striploin and averaged to obtain a representation of the post retail lean color.  
External fat color was obtained by averaging the two measurements from the external fat.  
27 
The ribeye and striploin steaks were vacuumed packaged and frozen at -20?C until 
sensory and TBARS analyses. 
Sensory 
 Striploin steaks for sensory were thawed (4?C for 12-18 h), weighed, and placed 
in a pre-heated George Foreman clam-shell-style grill (Model GRP4A, Macon, MO) for 7 
min (Kerth et al., 2007), resulting in a final internal temperature of 71?C (AMSA, 1995).  
Cooked steaks were weighed to determine the percentage cooking loss by dividing the 
weight lost during cooking by the pre-cooked weight. Each steak was trimmed of fat and 
connective tissue after cooking and the longissimus muscle from each steak was cut into 
cubes 1cm x 1cm x steak thickness and placed in double boilers, with warm sand in the 
bottom, until served to a six-member trained sensory panel.  Each of the trained panel 
members evaluated two samples from each steak in a cubicle supplied with red light; 
evaluation forms; two salt-free saltine crackers and water for cleansing the palate; and a 
cup for expectoration.  An eight-point scale was used for the evaluations of initial and 
sustained juiciness, initial and sustained tenderness, flavor intensity, and off flavor (1= 
extremely dry, extremely tough, extremely bland and no off flavor to 8= extremely juicy, 
extremely tender, extremely intense beef, and extreme off flavor).  Panelists noted 
appropriate off flavor descriptors provided on form if scores were noted for an off flavor.   
Determination of Lipid Oxidative Stability 
 Lipid oxidative stability was analyzed by using the thiobarbituric acid (TBA) 
reactive substance assay modified from Buege and Aust (1978).  Ribeye samples used for 
lipid oxidative stability were removed from frozen storage and a 5-g sample was 
homogenized with 15 mL of distilled water.  Approximately 2 mL homogenate was 
28 
combined with 4 mL of trichloracetic/thiobarbituric acid reagent and 100 .notdef.g0002L of 10% 
butylatedhydroxyanisole.  Samples were incubated in a 99?C water bath for 15 min, 
allowed to cool in cold water for 10 min, and filtered through Whatman paper.  The 
absorbance of the samples was read against a blank containing like reagents at 531 nm.  
Malonaldehyde standards were constructed utilizing 1, 1, 3, 3-tetraethoxypropane and 
thiobarbituric acid reactive substances were reported as mg/5g of meat. 
Statistical Analysis 
 Data for sensory, cook-loss, off descriptors, and TBA was analyzed as a 2 
(pumped or non-pumped) by 4 (CO, HO, LO, or VAC packaging) factorial arrangement 
of a completely randomized design using GLM procedure of SAS.  Type of forage had no 
significant effect (P > 0.10) and was not included in the analyses.  Significant (P .notdef.g0001 0.05) 
main and interaction effect means were separated with Fisher?s protected LSD using the 
PDIFF option of LSMEANS in SAS.  For retail display data, the effect of day was 
analyzed as a repeated measure using the replication within packaging and pump 
treatment as the error term for packaging, pump, and their interaction, and the residual 
error to test for day and day interaction effects.  The effect of the three different forages 
was tested and found to not be a significant (P> 0.10) source of variation, so data for 
forage type was pooled together for analyses. 
RESULTS 
 
Initial Color 
 The interaction of MAP*Day*Pump was not significant (P > 0.05) for the CIE L* 
instrumental value for striploin and ribeye steaks (Figure 3.1 and 3.17).  No differences 
(P > 0.05) in L* were found among packaging or pump treatments at the beginning of the 
29 
shelf life.  The CO and HO packaging increased (P < 0.05) the CIE L* value while the 
vacuum packaging decreased the L* value for the striploin and ribeye steaks at the end of 
shelf life.  The non-pumped striploin and ribeye steaks resulted in higher (P < 0.05) L* 
values than the pumped treated steaks.   
For a* value the interaction of MAP*Day*Pump was significant (P < 0.05) for the 
striploin steaks (Figure 3.2).  At the beginning of retail display a* was not different (P > 
0.05) for all MAP and pump treatments.  By the end of the retail display, a* values were 
the highest for CO and lowest for HO (P <0.05).  The a* values for HO, LO, and Vac had 
decreased (P < 0.05) significantly by the end of the retail display.  Non-pumped a* values 
were higher (P < 0.05) than pumped a* values within HO at the end of retail display.  The 
interaction of MAP*Day*Pump for ribeye steaks was not significant (P > 0.05; Figure 
3.18).  All modified atmosphere packages decreased in a* at the end of the retail display 
except for CO which increased (P > 0.05).  The non-pumped a* values (P < 0.05) were 
higher than the pumped a* within the CO and HO at the end of retail display. 
 At the beginning of retail display b* was not different (P > 0.05) for all MAP and 
pump for the striploin steaks (Figure 3.3).  By the end of retail display, b* values for LO 
and Vac were the lowest (P < 0.05).  The non-pumped b* p-value was higher than the 
pumped b* within LO and HO at the end of retail display for the striploin steaks.  For the 
ribeye steaks, the b* was not different (P > 0.05) at the beginning of the retail display for 
all MAP and pump (Figure 3.19).  The b* values for the pumped ribeyes were lower (P < 
0.05) than the non-pumped b* at the end of the retail display for all MAP.   
 For the striploin steaks, the pumped steaks had a higher fat L* values than non-
pumped fat L* values (P < 0.05; Figure 3.4).  The HO fat had the highest (P < 0.05) L* 
30 
value for both pumped and non-pumped.  CO and HO ribeyes had higher (P < 0.05) fat 
L* values than LO or Vac fat L* values for ribeyes (Figure 3.20).   
 The striploin fat a* was the highest (P < 0.05) for CO and lowest for HO than all 
other MAP (Figure 3.5).  There was no difference (P > 0.05) between the non-pumped 
and pumped fat a*.  Non-pumped, CO ribeyes had higher fat a* values than pumped CO 
fat a* values (Figure 3.21).  CO fat a* values were the highest for both pumped and non-
pumped ribeyes.  The fat b* values for the HO in the striploin and ribeye steaks was the 
lowest (P < 0.05) of all the MAPs (Figure 3.6 and 3.22).  
 At the beginning of retail display, there was no difference (P > 0.05) in hue values 
for all MAP and pump striploins (Figure 3.7).  By the end of retail display, HO had the 
highest (P < 0.05) hue value and CO had the lowest (P < 0.05) hue value.  Pumped 
striploins had a higher (P < 0.05) hue value within the CO and HO than the non-pumped 
hue values, but the pumped hue value was lower (P < 0.05) than the non-pumped hue 
value within the LO and Vac.  At end of the retail display, the ribeye HO steaks had the 
highest (P < 0.05) hue value and CO had the lowest (P < 0.05) hue value (Figure 3.23).  
The non-pumped ribeyes had a higher (P < 0.05) hue value than the pumped ribeyes 
within the LO and Vac at the end of retail display.   
 The chroma values for the striploin steaks at the beginning of retail display had no 
difference (P > 0.05) for all MAP and pump (Figure 3.8).  The CO had the highest (P < 
0.05) and HO pumped had the lowest (P < 0.05) chroma value at the end of retail display.  
The ribeye steaks had no difference (P > 0.05) at the beginning of the retail display for all 
of the MAP and pump (Figure 3.24).  The CO had the highest (P < 0.05) chroma value at 
31 
the end of retail display.  The non-pumped ribeyes had higher (P < 0.05) chroma values at 
the end of the retail display than the pumped ribeyes. 
 In the striploin steaks, the fat hue values were the higher (P < 0.05) for the HO in 
the pumped than the non-pumped (Figure 3.10).  Fat Hue values for the ribeye steaks 
were the highest (P < 0.05) for the HO and lowest for CO (Figure 3.25).   
 Striploin steaks had highest (P < 0.05) fat chroma values for both the pumped and 
non-pumped steaks within the CO (Figure 3.11).  The ribeye steaks had higher (P < 0.05) 
fat chroma values for the non-pumped steaks than the pumped steaks (Figure 3.26).  The 
CO fat chroma values were the highest (P < 0.05) for both pumped and non-pumped 
treatments. 
 The lean metmyoglobin values in the striploin steaks were the higher (P < 0.05) in 
the pumped steaks versus the non-pumped steaks within the HO (Figure 3.9). Vac non-
pumped had the lowest (P < 0.05) lean metmyoglobin values.  The HO in the ribeye 
steaks had the highest (P < 0.05) values for the lean metmyoglobin values (Figure 3.27).  
The pumped lean metmyoglobin values were higher (P < 0.05) than the non-pumped lean 
metmyoglobin values. 
Sensory 
 For all sensory characteristics, except for off flavor intensity and flavor intensity, 
the pumped striploin steaks had higher (P = 0.001) scores than the non-pumped striploin 
steaks (Table 3.1).  The HO treatment resulted in lower (P < 0.05) sensory traits except 
for the initial juiciness.  The off flavor intensity was highest for all of the pumped steaks 
versus the non-pumped steaks.  The HO non-pumped had higher (P < 0.05) off flavor 
intensity scores than all other MAP. 
32 
Off Flavor 
Non-pumped striploins had higher (P < 0.05) off flavor descriptor scores for 
bloody, bitter, grassy, and metallic than the pumped steaks (Table 3.2).  The HO 
packages were higher (P < 0.05) for bitter, but lower for grassy, and metallic off flavors 
than all other MAPs within the non-pumped.  For the rancid and salty off flavor 
descriptors within the HO were significantly different (P < 0.05) from all other MAP.  
The non-pumped striploins showed a higher (P < 0.05) rancid off flavor than the pumped.  
The pumped striploins noted a higher (P < 0.05) salty off flavor than the non-pumped 
striploins. 
Retail shelf-life  
 The visual lean color for HO decreased (P < 0.05) in color scores over the day of 
retail display for both striploin and ribeye steaks.  Non-pumped striploins and ribeyes had 
higher (P < 0.05) color scores than the pumped (Figures 3.12 and 3.28).  The non-
pumped ribeye steaks decreased (P < 0.05) gradually for HO in color scores as the day of 
retail display lengthened. 
 On day 1 of the retail display there was no difference (P > 0.05) in the uniformity 
scores for the pumped and non-pumped striploins and ribeyes (Figures 3.13 and 3.29).  
On day 2 the CO pumped and HO non-pumped striploins increased (P < 0.05) in 
uniformity. The HO non-pumped and pumped striploins on day 5 increased (P < 0.05) in 
uniformity scores.  HO pumped and non-pumped ribeyes increased (P < 0.05) in 
uniformity scores for day 3 and day 5.  On day 4, both the CO pumped and non-pumped 
ribeyes increased (P < 0.05).  Day 2 LO non-pumped ribeyes increased (P < 0.05). 
33 
The discoloration scores for the striploin steaks increased (P < 0.05) for HO as the 
day of retail display increased (Figure 3.14).  As the day of display increased, the CO 
remained relatively consistent in color and LO discoloration decreased (P < 0.05).  The 
discoloration scores for the ribeye steaks within the CO had the lowest (P < 0.05) scores.  
The HO scores increased (P < 0.05) as the day of retail increased.  The pumped steaks 
showed a more gradual decrease (P < 0.05) versus the non-pumped steaks which had a 
rapid decrease (P < 0.05) in discoloration scores within the LO (Figure 3.30). 
 The HO treatment for the striploin and ribeye steaks increased (P < 0.05) in lean 
browning scores as the day of retail display increased (Figures 3.15 and 3.31).  The CO 
scores remained unchanged. 
Lipid oxidation 
 Lipid oxidation was noted more (P < 0.05) in the pumped ribeyes than the non-
pumped (Figure 3.16).  The CO and HO showed higher (P < 0.05) tbars scores than the 
LO and vac.  The lowest (P < 0.05) scores were noted in the LO for the pumped ribeyes. 
 
DISCUSSION 
Initial Color 
Modified atmosphere packaging is commonly used to extend shelf-life and meat 
quality of beef.  A combination of 20-30% CO
2
 and 70-80% O
2
 gases are normally used 
for fresh MAP beef (Blakistone, 1998).  A study by O?Sullivan et al. (2003) stated that 
the levels for lipid oxidation were much higher in the MAP beef steak samples when 
compared to the aerobic packaged samples.  Even though greater color stability is due to 
high oxygen levels, which support oxymyoglobin formation, and carbon dioxide, which 
34 
acts as an antimicrobial agent, often associated with MAP; the high oxygen content of 
MAP can eventually lead to lipid oxidation and decrease color (Zhao et al., 1994). 
The study by Robbins et al. (2003b), agrees with the present study that the non-
pumped or control steaks have higher L*, a*, and b* values than the pumped or enhanced 
steaks.   The a* values in the present study for the striploin and ribeye steaks decreased 
by the end of the retail display for all MAP except the CO which increased.  The 
reduction in a* values demonstrates that there was a discoloration (loss) in red color.  A 
study by Hunt et al. (2004) also stated similar results for the decreasing values for a* 
within ground beef, longissimus dorsi, and outside semimembranosus.  The present study 
agrees with the study conducted by Stika et al. (2007) in which the pumped steaks 
resulted in lower a*, b*, and chroma or saturation index values than the non-pumped 
steaks because of the beef flavoring agent which was dark in color.  The Fat a* values for 
the CO in both the striploins and ribeyes were higher than all other MAPs.  The HO 
tended to increase the lightness of the Fat L*.  Hue values increased for HO, LO, and Vac 
by the end of retail display for both striploins and ribeyes.  The present study disagrees 
with the study by Robbins et al. (2002) which stated that hue angles increased 
significantly and to a greater degree in enhanced steaks when compared to the control 
steaks.  The hue for HO increased significantly when compared to other MAPs and 
pumped was higher than non-pumped.  The increase in hue value indicates that the color 
was moving away from the true red axis.   The chroma values for both the striploins and 
ribeyes decreased significantly within the HO, LO, and Vac.  The CO increased slightly.  
This study agrees with the study by Robbins et al. (2002) which states that the decrease in 
chroma values indicates that the intensity of the red color is decreasing.  
35 
Sensory 
 In the present study, the pumped treatment increased the sensory scores for 
juiciness, tenderness, off flavor, and decreased the cook-loss percent.  The present study 
agrees with the study by Robbins et al. (2002) where enhancement of beef round steaks 
increased the sensory scores for tenderness and juiciness.  The present study decreased 
the cook-loss percent for pumped steaks when compared to non-pumped steaks.  The 
study by Robbins et al. (2002) disagrees with the present study, stating that enhancement 
increased the cook-loss percent when compared to a no-pump control.  Pumped steaks 
were more salty when compared to the non-pumped steaks, which was expected since the 
injection treatment contained sodium phosphate and salt.   
Off Flavor 
 In grass-fed beef, off flavors such as bitter, bloody, livery, salty, and metallic have 
been noted by several researchers (Robbins et al., 2002; Reverte et al., 2003; Stika et al., 
2007).  The panelists in the present study noted the same off flavors for the pumped and 
non-pumped striploins.  The pumped striploins masked the grassy off flavor and 
decreased other off flavors as noted because of the addition of a beef flavoring agent.  
Similar observations were also noted by Reverte et al. (2003) and Stika et al. (2007). 
Retail shelf-life 
 In the present study, the color scores decreased for all MAP for both the striploin 
and ribeye steaks.  The non-pumped steaks had greater color scores than the pumped 
steaks.  Data by Robbins et al. (2003b) supports the findings from the present study.  The 
uniformity of the steaks were influenced by the MAP*Day interaction.  As the retail 
display increased, the uniformity scores increased representing as less uniform product by 
36 
the end of the retail display.  The HO treatment tended to show the most changes in 
uniformity.  Discoloration and metmyoglobin formation was noted the highest in the HO.  
The increase in discoloration and metmyoglobin values coincides with the low a* values 
for the HO packages.  Results from Pietrasik et al. (2006) supports the findings from the 
present study as noted that as the retail display lengthened, more browning or 
discoloration was noted.   Leakers were noted in several MAP packages that may result in 
lower shelf-life, sensory, and TBARS scores. 
Lipid oxidation 
 In the present study thiobarbituric reactive substance values (TBARS) was 
conducted only on the ribeye steaks.  The pumped ribeyes resulted in higher TBARS 
values than the non-pumped.  As noted by other researchers, the increased TBARS values 
may be due to the addition of salt which serves as a prooxidate which promotes pigment 
oxidation by lowering the oxygen tension and decreasing the meat?s buffering capacity, 
therefore the potential for myoglobin oxidation is increased (Seideman et al., 1984 and 
Akamittath et al., 1990).  The Houben et al. (2000) study states that with the higher the 
amounts of grass percentage, the less lipid oxidation.  This demonstrates the antioxidant 
effect of Vitamin E.   
IMPLICATIONS 
 The results in the present study indicated that the pumped treated steaks did not 
have as well of color stability instrumentally as the non-pumped steaks in the retail 
display.  Overall sensory characteristics were improved by the pumped treatment.  The 
carbon monoxide packaging maintained the bright-cherry, red color that consumers 
desire.   
  
 
 
37 
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d
er
n
es
s
, Su
s
t
ai
n
ed
 
T
en
d
e
rn
es
s
,
 Fl
av
o
r
 In
t
en
s
i
t
y
, 
O
f
f 
Fl
av
o
r,
 an
d
 
Co
o
k
 
L
o
s
s
%
 
res
p
ect
i
v
el
y
. 
 
38 
T
ab
l
e 
3.2.  I
nci
denc
e o
f
 Of
f
 f
l
av
or
 d
es
c
r
ipt
o
r
s 
a
s a
 p
er
c
ent
 
f
or
 str
i
p
l
o
i
n s
t
ea
k
s f
o
r
 
n
on-
pu
m
p
e
d and pum
ped 
i
n
j
ec
ti
on 
t
r
eat
m
ent
s and 
MAP pac
k
ag
es
.
 
 a
,
 
b,
 
c
,
 
d
 Me
ans
 
i
n a 
r
ow wit
h 
di
f
f
erent supe
r
s
cri
pts dif
f
er 
f
or
 
(
P <
 0.
05)
.
 
e
CO=Carbon m
onoxi
d
e pa
c
k
ag
i
n
g
, HO=Hi
g
h Ox
y
g
en 
pac
k
ag
i
ng
, LO
=Low oxyg
en pa
ck
ag
i
ng
, V
ac
=
Vac
uum
 Pack
ag
i
ng
 
 
 
N
o
n-
P
u
m
p
e
d
 
P
u
m
p
e
d
 
P
 
> 
F
 
 
CO
e 
HO
 
LO
 
V
a
c
 
CO
 
HO
 
LO
 
V
a
c
 
P
u
m
p
 
MA
P
 
P
u
m
p
*
M
A
P
 
Other
 
0
.
8
?0
.
7
7
 
0
.
6
?
0.
6
3
 
2
.
1
?
0.
7
2
 
0
.
7
?
0.
7
5
 
0
.
0
?
0.
6
8
 
0
.
0
?
0.
6
2
 
1.
9
?
0.
6
8
 
0
.
6
?
0.
6
7
 
0
.
3
9 
0
.
0
6 
0
.
9
6
 
Rancid
 
1
8
.
2
?
3
.
87
c 
6
2
.
0
?
3
.
15
a 
2
5
.
8
?
3
.
59
c 
1
8
.
2
?
3
.
73
c 
2
4
.
0
?
3
.
38
c 
5
0
.
0
?
3
.
12
b 
1
7
.
0
?
3
.
42
c 
2
3
.
1
?3
.
35
c 
0
.
3
1 
0
.
0
0
1 
0
.
0
1
 
B
lo
o
d
y
 
1
.
6
?
1.
0
3
 
0
.
6
?
0.
8
4
 
3
.
4
?
0.
9
5
 
4
.
4
?
0.
9
9 
1
.
2
?
0.
9
0
 
0
.
1
?
0.
8
3
 
1
.
3
?
0.
9
1
 
0
.
0
3
?
0
.
89
 
0
.
0
0
4
 
0
.
0
8 
0
.
1
2
 
B
itter
 
3
.
2
?
1.
5
4
b 
4
.
3
?
1.
2
6
b 
2
.
8
?
1.
4
3
b 
8
.
7
?
1.
4
9
a 
2
.
4
?
1.
3
5
b 
1
.
1
?
1.
2
4
b 
1
.
2
?
1.
3
6
b 
3
.
0
?
1.
3
4
a 
0
.
0
0
4
 
0
.
0
3 
0
.
3
1
 
Gr
ass
y 
2
4
.
5
?
3
.
12
a 
1
8
.
9
?
2
.
54
b 
2
2
.
4
?
2
.
89
ab 
2
4
.
8
?
3
.
00
a 
1
3
.
8
?
2
.
72
a 
4
.
2
?
2.
5
1
b 
8
.
0
?
2.
7
6
ab
 
1
0
.
7
?
2
.
70
a 
0
.
0
0
1
 
0
.
0
3 
0
.
8
8
 
L
i
ver
y 
0
.
0
?
0.
6
9 
1
.
1
?
0.
5
7 
1
.
4
?
0.
6
4 
0
.
7
1
?
0
.
67 
0
.
0
?
0.
6
1 
1
.
5
?
0.
5
6
 
0
.
0
?
0.
6
1 
0
.
0
?
0.
6
0 
0
.
3
6 
0
.
1
7 
0
.
4
2
 
Salt
y 
7
.
7
?
3.
6
0
c 
8
.
9
?
2.
9
3
c 
9
.
2
?
3.
3
4
c 
3
.
8
?
3.
4
7
c 
5
1
.
5
?
3
.
14
a 
4
1
.
0
?
2
.
90
b 
5
5
.
7
?
3
.
19
a 
5
3
.
7
?
3
.
12
a 
0
.
0
0
1
 
0
.
1
1 
0
.
0
2
 
Me
tallic
 
8
.
6
?
1.
9
7
ab
 
3
.
1
?
1.
6
0
b 
8
.
0
?
1.
8
2
a 
8
.
1
?
1.
8
9
a 
2
.
4
?
1.
7
2
ab
 
1
.
5
?
1.
5
8
b 
8
.
0
?
1.
7
4
a 
4
.
7
?
1.
7
1
a 
0
.
0
2 
0
.
0
0
5 
0
.
3
5
 
 
39 
Figure 
3.
1
. 
Least 
square 
means 
? 
SEM 
for 
CIE 
L* 
instrumental 
values 
of 
striploin 
steaks 
by 
pumped 
and 
non
-
pumped 
treatments 
at 
beginning 
and 
end 
of 
retail 
display 
for 
MAP.
 
M= 
modified 
atmosphere 
packaging, 
P= 
pump
ed
 
or 
no
n
-
pump
ed
, 
D= 
day 
of 
retail 
display.
 
CO= 
Carbon 
monoxide, 
LO= 
Low 
oxygen, 
HO= 
High 
oxygen, 
Vac= 
Vacuum 
packed; 
1
CIE 
L* 
Value 
(increasing value indicates a lighter color).
 
 
0 2 4 6 8 
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 
Beginning Pumped 
Beginning Non-Pumped 
End Pumped 
End Non-Pumped 
1
CIE L* Values
 
M = 0.001, P
 = 0.001, D = 0.03, M*P
 = 0.87, M*D = 0.001, P*D = 0.97, M*P*D = 0.76 
CO 
LO 
HO  
V
ac 
!
40 
F
i
g
u
re 3
.2
. 
 
L
e
as
t s
q
u
ar
e 
m
e
a
n
s
 ? 
SE
M fo
r C
I
E a*
 in
s
tru
m
en
tal v
alu
es
 
o
f
 s
tri
p
lo
in
 s
t
e
ak
s
 b
y
 p
u
m
p
ed
 
a
n
d
 n
o
n
-p
u
m
p
ed
 tre
atm
en
ts
 
at b
e
g
i
n
n
in
g
 
an
d
 en
d
 o
f 
r
etail
 d
is
p
l
a
y
 
fo
r 
M
A
P
. 
M=
 
m
o
d
i
fied
 atm
o
s
p
h
ere p
a
c
k
a
g
i
n
g
, 
P
=
 p
u
m
p
ed
 
o
r
 
n
o
n
-p
u
m
p
ed
,
 D=
 d
a
y
 
o
f retail
 d
is
p
l
a
y
. 
CO=
 Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 o
x
y
g
e
n
,
 
Vac=
 Va
cu
u
m
 
p
ac
k
ed
; 
1
C
I
E
 a*
 
V
alu
e
 
(p
o
s
i
tiv
e =
 
red
,
 0
 =
 
n
eu
tral,
 n
e
g
ati
v
e =
 
g
reen
).
 
 
!
02468
1012141618202224262830
B
eg
in
n
in
g
 
P
u
m
p
ed
B
eg
in
n
in
g
 
No
n
-P
u
m
p
ed
En
d
 
P
u
m
p
ed
E
n
d
 
N
o
n
-Pu
m
p
ed
1
C I E a*  V alu es
CO
LO
HO 
V
ac
M
 
=
 
0.
0
0
1
, 
P
 =
 
0
.2
8
,
D 
=
 
0
.0
0
1
, 
M
*
P
=
 0
.
37
,
 
M
*
D
 
=
 0
.
0
0
1
,
 
P
*
D 
=
 
0
.4
3
,
M
*
P
*
D
 
=
 
0
.
0
1
!
41 
F
i
g
u
re 3
.3
. 
 
L
e
as
t s
q
u
ar
e 
m
e
a
n
s
 ? 
SE
M fo
r C
I
E b
*
 in
s
tru
m
en
t
al v
alu
e
s
 
o
f 
s
trip
lo
in
 s
teak
s
 b
y
 
p
u
m
p
ed
 
a
n
d
 n
o
n
-p
u
m
p
ed
 
treatm
en
ts
 at 
b
e
g
in
n
i
n
g
 a
n
d
 
en
d
 o
f ret
ai
l d
is
p
la
y
 
f
o
r MA
P
.
 
M=
 m
o
d
ified
 
at
m
o
s
p
h
er
e p
a
ck
a
g
in
g
,
 P
=
 
p
u
m
p
ed
 o
r n
o
n
-
p
u
m
p
ed
,
 D=
 d
a
y
 o
f 
re
t
ail
 d
is
p
la
y
. C
O=
 C
arb
o
n
 m
o
n
o
x
i
d
e,
 L
O=
 
L
o
w 
o
x
y
g
en
, 
HO=
 
Hi
g
h
 
o
x
y
g
e
n
, V
ac=
 Vacu
u
m
 p
a
c
k
ed
; 
1
CI
E
 b
*
 
Valu
e
 
(p
o
s
it
iv
e
 
=
 
y
ell
o
w,
 0
 =
 
n
eu
tral,
 n
e
g
at
i
v
e =
 b
lu
e).
!
!
02468
101214161820222426
B
eg
in
n
in
g
 
P
u
m
p
ed
B
e
g
in
n
in
g
 
No
n
-P
u
m
p
ed
E
n
d
 
P
u
m
p
ed
E
n
d
 
N
o
n
-P
u
m
p
ed
1
C I E  b *  V alu es
CO
LO
HO
 
V
ac
M
=
 0
.
0
0
2
, P
 =
 0
.0
1
,
 D
=
 0
.0
0
1
,
M*
P
 =
 
0
.3
1
,
 M*
D 
=
 
0
.0
0
1
,
 P
*
D =
 
0
.
0
4
, 
M*
P*
D =
 0
.0
9
!
42 
!
F
i
g
u
re 3
.4
. 
 
L
e
as
t s
q
u
ar
e 
m
e
a
n
s
 ? 
SE
M fo
r C
I
E 
F
a
t 
L
*
 
in
s
tru
m
e
n
tal 
v
alu
es
 
o
f s
t
rip
lo
in
 
s
teak
s
 
b
y
 p
u
m
p
ed
 
an
d
 
n
o
n
-p
u
m
p
e
d
 
treatm
en
ts
 at 
th
e 
e
n
d
 o
f r
etai
l d
is
p
la
y
 
fo
r 
MAP
.
 
M=
 m
o
d
ified
 atm
o
s
p
h
ere p
ack
a
g
in
g
,
 
P
=
 p
u
m
p
ed
 o
r 
n
o
n
-p
u
m
p
ed
; CO
=
 
Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 
o
x
y
g
e
n
, 
V
ac=
 Va
cu
u
m
 
p
ac
k
e
d
; 
1
CI
E
 
F
at 
L
*
 
Valu
e (i
n
cr
eas
in
g
 
v
alu
e 
in
d
i
ca
t
e
s
 
a li
g
h
t
er co
lo
r
).
 
!
048
121620242832364044485256606468
Pu
m
p
ed
No
n
-P
u
m
p
ed
1
C I E F at L *  V alu es
M
 =
 0
.0
0
1
,
 
P
 
=
 0
.
0
2,
 
M
*
P
 
=
 
0
.4
2
CO
LO
HO 
V
ac
! !
43 
Figure 
3.
5
. 
 
Least square means ? SEM
 
for CIE 
Fat 
a* instrumental values of striploin steaks
 
by pumped and non
-
pum
ped 
treatments at the 
end of retail display for MAP. M= modified atmosphere packaging, P= pump
ed or non
-
pump
ed
;
 CO= 
Carbon monoxide, LO= Low oxygen, HO= 
High oxygen, Vac= Vacuum packed; 
1
CIE 
Fat 
a* Value (positive = red, 0 = 
neutral, 
negative = green). 
 
!
0 2 4 6 8 
10 12 14 16 18 20 
Pumped 
Non-Pumped 
1
CIE Fat a* Values
 
CO 
LO 
HO  
V
ac 
M = 0.001, P
 = 0.26,
  
M*P
 = 
0.66 
!
44 
Figure 
3.
6
. Le
ast square means ? SEM 
for CIE
 Fat
 b
* instrumental values of striploin steaks
 
by pumped and non
-
pumped 
treatments at 
the
 end of retail display for MAP. M= modified atmosphere packaging, P= pump
ed
 or no
n
-
 pump
ed;
 CO= 
Carbon monoxide, LO= Low oxygen, HO= 
High oxygen, Vac= Vacuum packed; 
1
CIE 
Fat 
b* Value (positive = yellow, 0 
= neutral, negative = blue).
!
!
0 2 4 6 8 
10 12 14 16 18 20 22 24 26 
Pumped 
Non-Pumped 
1
CIE Fat b* Values
 
CO 
LO 
HO  
V
ac 
M= 0.001, P
 = 0.42
,
 M*P
 = 0.46 
! !
45 
Figure 
3.
7.  Lea
st square means ? SEM for lean Hue
 instrumental values of striploin steaks by pumped and non
-
pumped 
treatments at beginning and end of retail display for MAP. M= modified atmosphere packaging, P= pumped or non
-
pumped, D= day of retail display. CO= Carbon monoxide, LO= Low oxygen, HO= High 
oxygen, Vac= Vacuum packed; 
1
Lean 
Hue 
Value (numerically de
creasing 
true red color
).
 
 
0 
10 20 30 40 50 60 70 80 
Beginning Pumped 
Beginning Non-Pumped 
End Pumped 
End Non-Pumped 
1
Hue Values 
M = 0.001, P
 = 0.73, D = 0.001, M*P
 = 0.005, M*D = 0.001, P*D = 0.46, M*P*D = 0.001 
CO  
HO 
LO 
V
ac 
! !
46 
Figure 
3.
8
.  Lea
st square means ? SEM for lean 
Chroma
 instrumental values of striploin steaks by pumped and non
-
pumped 
treatments at beginning and end of retail display for MAP. M= modified atmosphere packaging, P= pumped or non
-
pumped, D= day of retail display
. CO= carbon monoxide, LO= low oxygen, HO= high 
oxygen, Vac= v
acuum packed; 
1
Lean 
Chroma 
Value (numerically increasing 
color saturation
).
 
 
0 5 
10 15 20 25 30 35 40 
Beginning Pumped 
Beginning Non-Pumped 
End Pumped 
End Non-Pumped 
1
Chroma  Values 
M = 0.001, P
 = 0.13, D = 0.001, M*P
 = 0.89, M*D = 0.001, P*D = 0.24, M*P*D = 0.09 
CO  
HO 
LO 
V
ac 
! !
47 
F
i
g
u
re 3
.9
. 
 
L
e
as
t s
q
u
ar
e 
m
e
a
n
s
 ? 
SE
M fo
r l
e
an
 
m
etm
y
o
g
lo
b
in
 in
s
tru
m
en
t
al
 v
alu
es
 
o
f 
s
trip
lo
in
 s
teak
s
 b
y
 
p
u
m
p
e
d
 
an
d
 n
o
n
-
p
u
m
p
ed
 
tr
eat
m
en
t
s
 th
e e
n
d
 o
f 
retail d
is
p
la
y
 fo
r 
M
AP
. 
M=
 
m
o
d
ifi
e
d
 
atm
o
s
p
h
ere p
a
c
k
a
g
in
g
, 
P=
 
p
u
m
p
ed
 o
r n
o
n
-
p
u
m
p
ed
. 
CO=
 carb
o
n
 m
o
n
o
x
id
e
,
 LO=
 l
o
w 
o
x
y
g
en
, 
H
O=
 
h
i
g
h
 o
x
y
g
e
n
,
 V
ac=
 
v
acu
u
m
 p
a
c
k
ed
; 
1
L
ean
 
M
et
m
y
o
g
l
o
b
in
 p
er
ce
n
ta
g
e
 
(o
x
i
d
ized
 m
y
o
g
lo
b
in
 p
i
g
m
en
t)
 
 
0
20406080
100120140160180
Pu
m
p
ed
No
n
-
Pu
m
p
ed
1
Metm y o g l o b in , %
M
 
=
 0
.0
0
1
,
 P
 =
 
0
.
0
0
5
, M
*
P
 
=
 0
.0
0
1
C
O 
HO
LO
V
ac
! !
48 
F
i
g
u
re 3
.1
0
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r f
at 
H
u
e 
i
n
s
t
ru
m
en
t
al v
alu
es
 o
f
 s
tri
p
l
o
i
n
 
s
tea
k
s
 b
y
 p
u
m
p
ed
 a
n
d
 n
o
n
-p
u
m
p
ed
 
treatm
en
ts
 at 
th
e 
e
n
d
 o
f r
etai
l d
is
p
la
y
 
fo
r 
MAP
.
 
M
=
 m
o
d
ified
 atm
o
s
p
h
ere p
ack
a
g
in
g
,
 
P
=
 p
u
m
p
ed
 o
r 
n
o
n
-p
u
m
p
ed
; CO
=
 
Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 
o
x
y
g
e
n
, 
V
ac=
 Va
cu
u
m
 
p
ac
k
e
d
; 
1
F
at 
Hu
e
 
Valu
e 
(n
u
m
eri
call
y
 i
n
cre
as
in
g
 
tru
e red
 
co
l
o
r
).
 
0
1020304050607080
P
u
m
p
ed
No
n
-
Pu
m
p
ed
1
F at H u e V alu es
M
 
=
 
0
.
0
0
1
, P
 =
 
0
.5
6
, M
*
P
 
=
 0
.0
0
1
C
O
 
HO
LO
V
ac
! !
49 
!
Figure 
3.
11
.  Lea
st square means ? SEM for fat
 
Chroma
 instrumental values of striploin steaks by pumped and non
-
pumped 
treatments at 
the
 end of retail display for MAP. M= modified atmosphere pack
aging, P= pumped or non
-
pumped;
 CO= 
carbon monoxide, LO= low oxygen, HO= high oxygen, Vac= v
acuum packed; 
1
Fat
 
Chr
oma 
Value (numerically 
increasing 
color saturation
).
 
 
0 5 
10 15 20 25 30 35 40 
Pumped 
Non-Pumped 
1
 Fat Chroma  Values 
M = 0.001, P
 = 0.003, M*P
 = 0.03 
CO  
HO 
LO 
V
ac 
! !
50 
F
i
g
u
re 3
.1
2
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r v
is
u
al
 l
ean
 co
l
o
r 
o
f
 s
trip
lo
in
 s
t
e
a
k
s
 b
y
 ret
ail 
d
i
s
p
l
ay
 d
a
y
 with
in
 p
u
m
p
ed
 an
d
 
n
o
n
-
p
u
m
p
ed
 
tr
eat
m
en
t
s
 fo
r 
M
AP
.
 
M=
 m
o
d
ified
 
atm
o
s
p
h
ere p
a
c
k
a
g
in
g
,
 
P =
 
p
u
m
p
e
d
 o
r 
n
o
n
-p
u
m
p
e
d
, 
D =
 
d
ay
 
o
f 
ret
a
il d
is
p
la
y
. 
CO =
 carb
o
n
 m
o
n
o
x
id
e, LO =
 lo
w o
x
y
g
en
, H
O 
=
 
h
i
g
h
 o
x
y
g
en
;
 
1
L
ean
 
co
lo
r
 (1
 =
 ex
t
rem
el
y
 
d
ar
k
 
red
; 
8
 =
 ex
trem
el
y
 b
ri
g
h
t
 
ch
err
y
-
red
)
 
01234567
D1
D2
D3
D4
D5
D1
D2
D3
D4
D5
1
V is u al L ean  C o l o r Sco re
M
 
=
 0
.0
0
1
, 
P
 =
 
0
.0
1
, D 
=
 
0
.
0
0
1
, M
*
P
 
=
 
0
.5
5
, M
*
D =
 0
.0
0
1
, 
P*
D =
 0
.3
6
,
 M
*
P
*
D =
 
0
.
6
8
C
O 
HO
LO
No
n
-Pu
m
p
ed
P
u
m
p
ed
 
!
51 
!
Figure 
3.
13
.  Lea
st square means ? SEM for 
visual lean 
uniformity
 
of striploin steaks by 
retail display day within 
pumped and 
non
-
pumped treatments for MAP. M= modified atmosphere packaging, P
 
= pumped or non
-
pumped, D
 
= day of retail 
display
.  
CO
 
= carbon
 monoxide, 
LO = low oxygen, HO = high oxygen
; 
1
Lean
 color
 
uniformity 
(
1 = 
uniform; 5
 =
 
e
xtreme two
-
toning
)
 
0 
0.25 
0.5 
0.75 
1 
1.25 
1.5 
D1 
D2 
D3 
D4 
D5 
D1 
D2 
D3 
D4 
D5 
1
Visual Lean Uniformity Score 
M = 0.03, P
 = 0.99, D = 0.001, M*P
 = 0.62, M*D = 0.001, P*D = 0.98, M*P*D = 0.75 
CO  
HO 
LO 
Non-Pumped 
Pumped
 
! !
52 
Figure 
3.
14
.  Lea
st square means ? SEM for 
visual lean 
discoloration
 
of striploin steaks by 
retail display day within 
pumped 
and non
-
pumped treatments for MAP. M= modified atmosphere packaging, P
 
= pumped or non
-
pumped, D
 
= day of 
retail display
.  
CO
 
= carbon monoxide, 
LO = low oxygen, HO = high oxygen
; 
1
Lean
 
discoloration
 
(
1 = 
none
; 
7
 =
 
total 
discoloration
)
 
0 1 2 3 4 5 6 7 
D1 
D2 
D3 
D4 
D5 
D1 
D2 
D3 
D4 
D5 
1
Visual Lean Discoloration Score 
M = 0.001, P
 = 0.31, D = 0.07, M*P
 = 0.14, M*D = 0.001, P*D = 0.15, M*P*D = 0.61 
CO  
HO 
LO 
Non-Pumped 
Pumped
 
! !
53 
Figure 
3.
15
.  Lea
st square means ? SEM for 
visual lean 
browning
 
of striploin steaks by 
retail display day within 
pumped and 
non
-
pumped treatments for MAP. M= modified atmosphere packaging, P
 
= pumped or
 non
-
pumped, D
 
= day of retail 
display
.  
CO
 
= carbon monoxide, 
LO = low oxygen, HO = high oxygen
; 
1
Lean
 
browning
 
(
1 = 
none
; 
5
 =
 
dark brown
)
 
0 
0.5 
1 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
5 
D1 
D2 
D3 
D4 
D5 
D1 
D2 
D3 
D4 
D5 
1
Visual Lean Browning Score 
M = 0.001, P
 = 0.03, D = 0.63, M*P
 = 0.08, M*D = 0.002, P*D = 0.70, M*P*D = 0.75 
CO  
HO 
LO 
Non-Pumped 
Pumped
 
!
54 
Figure 
3.
16.  Least square means ? SEM for 
thiobarbituric reactive substance values of ribeye steaks at the end of retail display 
by pumped and non
-
p
umped treatments for MAP.  M = 
modi
fied atmosphere packaging, P = 
pumped or non
-
pumped; 
CO =
 carbon monoxide, HO = high oxygen, LO = l
ow oxygen
!
!
!
0 
0.2 0.4 0.6 0.8 
1 
1.2 1.4 1.6 1.8 
2 
2.2 2.4 
Pumped 
Non-Pumped 
Thiobarbituric Reactive Substances Values, mg/kg 
M = 0.003, P
 = 0.001, M*P
 = 0.25 
CO 
HO 
LO 
V
ac 
!
55 
F
i
g
u
re 3
.1
7
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M 
fo
r C
I
E
 
L
*
 i
n
s
t
ru
m
en
tal 
v
alu
es
 o
f ri
b
e
y
e s
te
a
k
s
 
b
y
 p
u
m
p
e
d
 an
d
 
n
o
n
-p
u
m
p
e
d
 t
re
a
t
m
e
n
ts
 
at b
e
g
i
n
n
in
g
 
an
d
 en
d
 o
f 
r
etail
 d
is
p
l
a
y
 
fo
r 
M
A
P
. 
M=
 
m
o
d
i
fied
 atm
o
s
p
h
ere p
a
c
k
a
g
i
n
g
, 
P
=
 p
u
m
p
ed
 
o
r 
n
o
n
-p
u
m
p
ed
,
 D=
 d
a
y
 
o
f retail
 d
is
p
l
a
y
.
 CO=
 Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 o
x
y
g
e
n
,
 
Vac=
 Va
cu
u
m
 
p
ac
k
ed
; 
1
C
I
E
 
L
*
 Val
u
e 
(in
cre
a
s
i
n
g
 v
alu
e in
d
ica
t
es
 
a li
g
h
te
r co
lo
r
).
 
02468
1012141618202224262830323436384042
B
eg
in
n
in
g
 
P
u
m
p
ed
B
eg
in
n
i
n
g
 
No
n
-Pu
m
p
ed
En
d
 
P
u
m
p
ed
E
n
d
 
N
o
n
-Pu
m
p
e
d
1
C I E L *  V alu es
M
 =
 
0
.0
0
1
, 
P
 =
 0
.0
0
1
, 
D 
=
 0
.1
1
, 
M
*
P
 
=
 0
.
5
7,
 
M
*
D
 
=
 0
.
00
1
,
 
P
*
D 
=
 
0
.9
6
, M
*
P
*
D 
=
 
0
.
4
7
CO
LO
HO 
V
ac
! !
56 
F
i
g
u
re 3
.1
8
. 
Leas
t
 s
q
u
ar
e
 m
e
an
s
 
?
 
S
E
M
 f
o
r 
C
I
E 
a
*
 
in
s
t
ru
m
en
tal 
v
alu
es
 o
f r
i
b
e
y
e
 s
tea
k
s
 
b
y
 p
u
m
p
ed
 
an
d
 
n
o
n
-p
u
m
p
ed
 
tre
atm
e
n
ts
 
at b
e
g
i
n
n
in
g
 
an
d
 en
d
 o
f 
r
etail
 d
is
p
l
a
y
 
fo
r 
M
A
P
. 
M=
 
m
o
d
i
fied
 atm
o
s
p
h
ere p
a
c
k
a
g
i
n
g
, 
P
=
 p
u
m
p
ed
 
o
r
 
n
o
n
-p
u
m
p
ed
,
 D=
 
d
ay
 o
f r
e
t
a
i
l d
is
p
la
y
. C
O
=
 C
a
r
b
o
n
 m
o
n
o
x
id
e,
 
L
O
=
 L
o
w
 
o
x
y
g
en
, 
H
O=
 
Hi
g
h
 
o
x
y
g
en
, 
Vac=
 Va
cu
u
m
 p
ac
k
ed
; 
1
C
I
E 
a*
 
Valu
e (p
o
s
i
tiv
e =
 
red
,
 0
 
=
 
n
eu
tral,
 n
e
g
ati
v
e =
 
g
re
e
n
).
 
 
!
02468
101214161820222426283032
B
eg
in
n
in
g
 
P
u
m
p
ed
B
eg
in
n
in
g
 
No
n
-P
u
m
p
ed
En
d
 
P
u
m
p
ed
E
n
d
 
N
o
n
-Pu
m
p
ed
1
C I E  a*  V alu es
M
 
=
 0
.0
0
1
,
 P
 
=
 
0
.
8
6
, 
D =
 0
.0
0
1
, 
M*
P
 
=
 
0
.
8
0
, 
M*
D =
 0
.0
0
1
,
 P*
D =
 0
.0
0
9
,
 M
*
P
*
D
 =
 
0
.
5
8
 
CO
LO
HO 
V
ac
! !
57 
F
i
g
u
re 3
.1
9
. 
Leas
t
 s
q
u
ar
e
 m
e
an
s
 
?
 
S
E
M
 f
o
r 
C
I
E 
b
*
 i
n
s
t
ru
m
en
tal v
alu
es
 o
f r
ib
e
y
e 
s
tea
k
s
 
b
y
 p
u
m
p
ed
 
an
d
 
n
o
n
-p
u
m
p
e
d
 t
re
a
t
m
en
ts
 
a
t
 
b
eg
in
n
in
g
 
a
n
d
 
en
d
 
o
f 
r
eta
il d
is
p
la
y
 
fo
r 
MA
P. 
M=
 
m
o
d
ifi
e
d
 
a
t
m
o
s
p
h
ere 
p
a
c
k
ag
in
g
, 
P=
 
p
u
m
p
e
d
 o
r 
n
o
n
-
p
u
m
p
ed
, 
D=
 
d
a
y
 o
f 
retail 
d
i
s
p
l
ay
. 
CO=
 Carb
o
n
 m
o
n
o
x
id
e, 
L
O=
 
L
o
w 
o
x
y
g
en
,
 
HO=
 Hi
g
h
 o
x
y
g
e
n
, 
Vac=
 Va
cu
u
m
 
p
ac
k
ed
; 
1
CI
E
 b
*
 
Va
l
u
e 
(p
o
s
i
tiv
e =
 
y
ell
o
w,
 0
 =
 n
e
u
tral
, n
e
g
at
iv
e 
=
 b
lu
e).
!
!
02468
10121416182022242628
B
eg
in
n
in
g
 
P
u
m
p
ed
B
e
g
in
n
in
g
 
No
n
-P
u
m
p
ed
E
n
d
 
P
u
m
p
ed
E
n
d
 
N
o
n
-P
u
m
p
ed
1
C I E  b *  V alu es
M
 
=
 0
.0
4
, P
 =
 
0
.2
0
,
 D 
=
 0
.0
0
1
,
 M
*
P
 =
 
0
.6
8
,
 M
*
D 
=
 
0
.
0
4
, 
P*
D =
 0
.0
0
1
, 
M*
P
*
D 
=
 
0
.
7
9
CO
LO
HO
 
V
ac
! !
58 
F
i
g
u
re 3
.2
0
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M 
fo
r C
I
E
 
F
at
 
L
*
 i
n
s
t
ru
m
en
tal v
alu
es
 o
f rib
e
y
e
 
s
t
ea
k
s
 
b
y
 p
u
m
p
ed
 
a
n
d
 
n
o
n
-p
u
m
p
e
d
 
treatm
en
ts
 at 
th
e 
e
n
d
 o
f r
etail
 d
is
p
la
y
 
fo
r
 
MAP
.
 
M=
 m
o
d
ified
 atm
o
s
p
h
ere p
ack
a
g
in
g
,
 
P
=
 p
u
m
p
ed
 o
r 
n
o
n
-p
u
m
p
ed
; CO
=
 
Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 
o
x
y
g
e
n
, 
V
ac=
 Va
cu
u
m
 
p
ac
k
e
d
; 
1
CI
E
 
F
at 
L
*
 
Valu
e (i
n
cr
eas
in
g
 
v
alu
e 
in
d
i
ca
t
e
s
 
a li
g
h
t
er co
lo
r
).
!
048
121620242832364044485256606468
P
u
m
p
ed
No
n
-P
u
m
p
ed
1
C I E F at L *  V alu es
M
 =
 0
.0
0
1
, 
P
 
=
 0
.
3
7,
 
M
*
P
 
=
 
0
.0
5
CO
LO
HO 
V
a
c
! !
59 
F
i
g
u
re 3
.2
1
. 
Leas
t 
s
q
u
ar
e
 m
e
an
s
 
?
 
S
E
M f
o
r 
C
I
E 
F
at 
a
*
 i
n
s
t
ru
m
en
tal 
v
alu
es
 
o
f ri
b
e
y
e s
te
a
k
s
 
b
y
 p
u
m
p
ed
 an
d
 
n
o
n
-p
u
m
p
ed
 
treatm
en
ts
 at 
th
e 
e
n
d
 o
f r
etai
l d
is
p
la
y
 
fo
r 
MAP
.
 
M
=
 m
o
d
ified
 atm
o
s
p
h
ere p
ack
a
g
in
g
,
 
P
=
 p
u
m
p
ed
 o
r 
n
o
n
-p
u
m
p
ed
; CO
=
 
Carb
o
n
 m
o
n
o
x
id
e, 
LO=
 
L
o
w o
x
y
g
e
n
,
 HO=
 Hi
g
h
 
o
x
y
g
e
n
, 
V
ac=
 Va
cu
u
m
 
p
ac
k
e
d
; 
1
CI
E
 
F
at 
a*
 
Valu
e
 
(p
o
s
it
iv
e 
=
 r
e
d
, 
0
 
=
 
n
e
u
tral,
 n
e
g
ati
v
e =
 
g
r
een
).
  
!
02468
10121416182022
Pu
m
p
ed
No
n
-P
u
m
p
ed
1
C I E F at a*  V a l u es
CO
LO
HO 
V
a
c
M
 =
 0
.0
0
1
,
 
P
 
=
 0
.
0
01
,
M
*
P
=
 0
.0
0
2
! !
60 
Figure 
3.
22
. Le
ast square means ? SEM
 
for CIE
 Fat
 b
* 
instrumental values of ribeye
 steaks
 
by pumped and non
-
pumped 
treatments at 
the
 end of retail display for MAP. M= modified atmosphere packaging, P= pump
ed
 or no
n
-
 pump
ed;
 CO= 
Carbon monoxide, LO= Low oxygen, HO= 
High oxygen, Vac= Vacuum packed; 
1
CIE 
Fat 
b* Value (positive = yellow, 0 = 
neutral, negative = blue).
!
!
0 2 4 6 8 
10 12 14 16 18 20 22 24 26 
Pumped 
Non-Pumped 
1
CIE Fat b* Values
 
CO 
LO 
HO  
V
ac 
M= 0.004, P
 = 0.12
,
 M*P
 = 0.70 
!
61 
Figure 
3.
23
.  Lea
st square means ? SEM for lean Hue
 
instrumental values of ribeye
 steaks by pumped and non
-
pumped 
treatments at beginning and end of retail display for MAP. M= modified atmosphere packaging, P= pumped or non
-
pumped, D= day of retail display. CO= Carbon monoxide, LO= Low oxygen, HO= High oxygen, Vac= Vacuum packed; 1
Lean
 
Hue 
Value (numerically de
creasing 
true red color
).
 
 
0 
10 20 30 40 50 60 70 
Beginning Pumped 
Beginning Non-Pumped 
End Pumped 
End Non-Pumped 
1
Hue Values 
M = 0.001, P
 = 0.62, D = 0.001, M*P
 = 0.85, M*D = 0.001, P*D = 0.05, M*P*D = 0.19 
CO  
HO 
LO 
V
ac 
! !
62 
Figure 
3.
24
.  Lea
st square means ? SEM for lean 
Chroma
 instrumental values of 
ribeye 
steaks by pumped and non
-
pumped 
treatments at beginning and end of retail display for MAP. M= 
modified atmosphere packaging, P= pumped or non
-
pumped, D= day of retail display
. CO= carbon monoxide, LO= low oxygen, HO= high oxygen, Vac= v
acuum packed; 
1
Lean 
Chroma 
Value (numerically increasing 
color saturation
).
 
 
0 5 
10 15 20 25 30 35 40 
Beginning Pumped 
Beginning Non-Pumped 
End Pumped 
End Non-Pumped 
1
Chroma  Values 
M = 0.001, P
 = 0.46, D = 0.001, M*P
 = 0.82, M*D = 0.001, P*D = 0.001, M*P*D = 0.87 
CO  
HO 
LO 
V
ac 
! !
63 
F
i
g
u
re 3
.2
5
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r f
at 
H
u
e 
i
n
s
t
ru
m
en
t
al v
alu
es
 o
f
 ri
b
e
y
e 
s
tea
k
s
 
b
y
 p
u
m
p
ed
 an
d
 
n
o
n
-p
u
m
p
e
d
 t
re
a
t
m
e
n
ts
 
at t
h
e en
d
 o
f r
etail 
d
i
s
p
l
a
y
 
f
o
r 
M
AP. 
M
=
 
m
o
d
i
fied
 
a
tm
o
s
p
h
e
re p
ac
k
a
g
i
n
g
, 
P
=
 p
u
m
p
ed
 
o
r 
n
o
n
-p
u
m
p
ed
;
 CO=
 C
arb
o
n
 
m
o
n
o
x
i
d
e,
 
L
O=
 
Lo
w 
o
x
y
g
en
, 
H
O=
 H
i
g
h
 o
x
y
g
e
n
, 
Vac=
 
Vac
u
u
m
 p
ack
ed
; 
1
F
a
t Hu
e 
Valu
e 
(n
u
m
e
ri
c
al
l
y
 in
cre
a
s
i
n
g
 tr
u
e r
e
d
 
co
l
o
r)
.
 
0
10203040506070
P
u
m
p
ed
No
n
-Pu
m
p
ed
1
Fat Hu e V a l u es
M
 
=
 0
.0
0
1
, 
P
 =
 
0
.1
5
, M
*
P
 
=
 0
.2
8
C
O 
HO
LO
V
ac
! !
64 
F
i
g
u
re 3
.2
6
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r f
at 
Ch
r
o
m
a i
n
s
tr
u
m
en
t
al v
alu
e
s
 o
f rib
e
y
e
 
s
te
a
k
s
 
b
y
 p
u
m
p
ed
 a
n
d
 n
o
n
-
p
u
m
p
e
d
 
treatm
en
ts
 at 
th
e 
e
n
d
 o
f r
etail
 d
is
p
la
y
 
fo
r
 
MAP
.
 
M=
 m
o
d
ified
 atm
o
s
p
h
ere p
ack
a
g
in
g
,
 
P
=
 p
u
m
p
ed
 o
r 
n
o
n
-p
u
m
p
ed
; CO
=
 
carb
o
n
 
m
o
n
o
x
id
e,
 
L
O=
 l
o
w 
o
x
y
g
e
n
, H
O=
 h
i
g
h
 o
x
y
g
e
n
,
 
V
ac=
 v
a
cu
u
m
 p
ac
k
ed
; 
1
F
at C
h
ro
m
a Valu
e 
(
n
u
m
e
ri
ca
l
l
y
 
in
crea
s
i
n
g
 co
lo
r s
atu
ratio
n
). 
 
05
10152025303540
P
u
m
p
ed
No
n
-P
u
m
p
ed
1
Fat C h ro m a  V alu es
M =
 0
.0
0
1
, P
 =
 
0
.0
0
2
, 
M*
P
 =
 
0
.
7
6
C
O 
HO
LO
V
ac
! !
65 
F
i
g
u
re 3
.2
7
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r le
an
 
m
et
m
y
o
g
lo
b
i
n
 
in
s
tru
m
e
n
tal 
v
alu
es
 o
f r
ib
e
y
e
 s
tea
k
s
 b
y
 
p
u
m
p
e
d
 
an
d
 n
o
n
-p
u
m
p
ed
 
treatm
en
ts
 th
e en
d
 
o
f
 
reta
il 
d
i
s
p
la
y
 
fo
r 
M
A
P. 
M=
 m
o
d
if
ied
 
a
t
m
o
s
p
h
er
e
 
p
a
c
k
ag
in
g
, 
P=
 
p
u
m
p
ed
 
o
r 
n
o
n
-p
u
m
p
e
d
. 
CO=
 
carb
o
n
 
m
o
n
o
x
id
e,
 
L
O=
 l
o
w 
o
x
y
g
e
n
, H
O=
 h
i
g
h
 o
x
y
g
e
n
,
 
V
ac=
 v
a
cu
u
m
 p
ac
k
ed
; 
1
L
ea
n
 
M
etm
y
o
g
lo
b
in
 p
e
r
c
en
t
a
g
e
 
(o
x
i
d
ized
 
m
y
o
g
lo
b
i
n
 
p
i
g
m
en
t)
 
 
0
20406080
100120140
Pu
m
p
ed
No
n
-Pu
m
p
e
d
1
Metm y o g l o b in , %
M
 
=
 0
.0
0
1
, 
P
 
=
 
0
.0
0
4
,
 M
*
P
 =
 0
.5
8
C
O 
HO
LO
V
ac
!
66 
F
i
g
u
re 3
.2
8
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r v
is
u
al
 l
ean
 co
l
o
r 
o
f
 rib
e
y
e 
s
te
ak
s
 b
y
 r
etail
 d
is
p
l
a
y
 
d
a
y
 
wi
t
h
i
n
 
p
u
m
p
e
d
 an
d
 n
o
n
-
p
u
m
p
ed
 
tr
eat
m
en
t
s
 fo
r 
M
AP
.
 
M=
 m
o
d
ified
 
atm
o
s
p
h
ere p
a
c
k
a
g
in
g
,
 
P =
 
p
u
m
p
e
d
 o
r 
n
o
n
-p
u
m
p
e
d
, 
D =
 
d
ay
 
o
f 
ret
a
il d
is
p
la
y
. 
CO =
 carb
o
n
 m
o
n
o
x
id
e, LO =
 lo
w o
x
y
g
en
, H
O 
=
 
h
i
g
h
 o
x
y
g
en
;
 
1
L
ean
 
co
lo
r
 (1
 =
 ex
t
rem
el
y
 
d
ar
k
 
red
; 
8
 =
 ex
trem
el
y
 b
ri
g
h
t
 
ch
err
y
-
red
)
 
012345678
D1
D2
D3
D4
D5
D1
D2
D3
D4
D5
1
V is u al L ea n  C o lo r Sco re
M
 
=
 0
.0
0
1
, 
P
 
=
 
0
.
0
0
9
, D 
=
 0
.0
0
1
,
 M
*
P
 =
 
0
.9
0
, M
*
D =
 
0
.
0
0
1
, P
*
D =
 0
.0
0
3
, 
M*
P*
D =
 
0
.3
5
C
O 
HO
LO
No
n
-
Pu
m
p
ed
P
u
m
p
ed
 
!
67 
F
i
g
u
re 3
.2
9
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r v
is
u
al
 l
ean
 u
n
if
o
r
m
i
t
y
 o
f 
rib
e
y
e 
s
tea
k
s
 b
y
 ret
ail
 d
is
p
la
y
 
d
a
y
 
wit
h
i
n
 
p
u
m
p
ed
 
an
d
 
n
o
n
-p
u
m
p
ed
 
treat
m
en
t
s
 f
o
r MA
P
.
 
M=
 
m
o
d
ified
 
at
m
o
s
p
h
e
r
e p
a
c
k
a
g
in
g
,
 P =
 
p
u
m
p
ed
 
o
r 
n
o
n
-p
u
m
p
ed
,
 D =
 d
a
y
 
o
f 
retail 
d
is
p
l
ay
.
  CO 
=
 
c
arb
o
n
 
m
o
n
o
x
i
d
e, 
L
O 
=
 l
o
w 
o
x
y
g
en
, 
HO
 =
 h
i
g
h
 o
x
y
g
en
; 
1
Le
a
n
 co
lo
r u
n
ifo
r
m
it
y
 (1
 
=
 u
n
i
fo
r
m
; 5
 =
 
ex
t
rem
e 
two
-to
n
i
n
g
)
 
0
0
.
2
5
0
.5
0
.
7
51
1
.
2
5
1
.5
D1
D2
D3
D4
D5
D1
D2
D3
D4
D5
1
V is u al L ea n  Un ifo rm it y  Sco re
M =
 
0
.
0
7
, 
P
 
=
 
0
.5
3
, D
 =
 
0
.
0
0
1
, M
*
P
 
=
 
0
.4
9
, M
*
D =
 0
.
0
0
1
, 
P*
D =
 0
.1
5
, M
*
P
*
D =
 
0
.2
8
C
O 
HO
LO
No
n
-Pu
m
p
e
d
P
u
m
p
e
d
 
!
68 
F
i
g
u
re 3
.3
0
.  
L
e
as
t s
q
u
ar
e 
m
ean
s
 
? S
E
M
 
fo
r v
is
u
al
 l
ean
 d
is
co
l
o
rati
o
n
 o
f r
ib
e
y
e
 s
tea
k
s
 b
y
 
retail 
d
is
p
la
y
 d
a
y
 
with
in
 p
u
m
p
ed
 an
d
 
n
o
n
-p
u
m
p
ed
 
treat
m
en
t
s
 f
o
r MA
P
.
 
M=
 
m
o
d
ified
 
at
m
o
s
p
h
e
r
e p
a
c
k
a
g
in
g
,
 P =
 
p
u
m
p
ed
 
o
r 
n
o
n
-p
u
m
p
ed
,
 D =
 d
a
y
 
o
f 
retail 
d
is
p
l
ay
. 
 CO 
=
 
c
arb
o
n
 
m
o
n
o
x
i
d
e, 
L
O 
=
 l
o
w 
o
x
y
g
en
, 
HO
 =
 h
i
g
h
 o
x
y
g
en
; 
1
Le
a
n
 d
is
co
lo
ratio
n
 
(1
 =
 
n
o
n
e; 7
 =
 to
tal 
d
is
co
lo
rati
o
n
) 
01234567
D1
D2
D3
D4
D5
D1
D2
D3
D4
D5
1
V i s u al L ean  Dis co l o rati o n  S co re
M =
 0
.0
0
9
,
 P
 =
 
0
.6
9
,
 D =
 0
.0
6
,
 M
*
P
 =
 
0
.9
7
, M
*
D =
 
0
.
0
0
1
, P
*
D =
 0
.1
6
,
 M
*
P
*
D 
=
 
0
.
0
0
1
C
O 
HO
LO
No
n
-Pu
m
p
e
d
P
u
m
p
e
d
 
!
69 
Figure 
3.
31
.  Lea
st square means ? SEM for 
visual lean 
browning
 
of 
ribeye
 steaks by 
retail display day within 
pumped and non
-
pumped treatments for MAP. M= modified
 atmosphere packaging, P
 
= pumped or non
-
pumped, D
 
= day of retail display
.  
CO
 
= carbon monoxide, 
LO = low oxygen, HO = high oxygen
; 
1
Lean
 
browning
 
(
1 = 
none
; 
5
 =
 
dark brown
)
 
0 
0.5 
1 
1.5 
2 
2.5 
3 
3.5 
D1 
D2 
D3 
D4 
D5 
D1 
D2 
D3 
D4 
D5 
1
Visual Lean Browning Score 
M = 0.001, P
 = 0.82, D = 0.04, M*P
 = 0.99, M*D = 0.001, P*D = 0.91, M*P*D = 0.73 
CO  
HO 
LO 
Non-Pumped 
Pumped
 
70 
CHAPTER IV  
 
CHARACTERIZING GRASS-FED GROUND BEEF USING MODIFIED 
ATMOSPHERE PACKAGING 
 
ABSTRACT 
 Eighteen kilograms of grass-fed beef trim from fall-born Angus x Continental 
crossbred steers and eighteen kilograms of grain-fed beef trim were ground to achieve 
separate batches with approximately 20% fat.  Six titrations were made from each of the 
ground trimmings containing: 0% grass/100% grain (0/100), 20% grass/80% grain 
(20/80), 40% grass/60% grain (40/60), 60% grass/40% grain (60/40), 80% grass/20% 
grain (80/20), and 100% grass/0% (100/0) grain.  Each titration was packaged using a 
high oxygen (HO; 80% O
2
/20% CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon 
monoxide (CO; 65% N
2
/34.6% CO
2
/0.4% CO) or OV (overwrap).  Results showed that 
there was no difference in diet*modified atmosphere packaging (MAP; P > 0.05) for 
initial and sustained juiciness, cohesiveness, flavor intensity, off flavor, or cookloss.  The 
100/0 titration resulted in better (P < 0.05) instrumental (a*) and visual color scores.  The 
CO package produced and maintained a bright, cherry-red color through out the retail 
display.  TBARS values were the lowest for the titrations with the most grass percentage 
(P < 0.05).   
71 
INTRODUCTION 
Forage-fed beef accounted for the majority of beef production and sales in the 
United States prior to World War II (Schupp et al., 1980).  Popularity of forage-fed beef 
declined in the 1950s and 1960s when the large-scale cattle finishing systems were 
developed which demanded an increase in grain-based finishing regimens.  Soon 
consumers became accustomed to the characteristics, such as flavor, tenderness, and 
juiciness, which results from high quality, well-marbled grain-fed beef.  During the late 
1970s, consumer health consciousness and demand for ?healthy? foods greatly increased 
due to a shift in the American diet (Schupp et al., 1980; Griebenow et al., 1997).   
Today consumers are still attracted to the promotion of ?healthy? foods.  Because 
of this demand, organic, natural, and grass-fed beef has regained recognition in niche 
markets which seems to follow the demand theory that states that consumers should be 
influenced by the factors related to human health and beef production supplies (Schupp et 
al., 1980).  Many consumers desire a product that is leaner and environmentally friendly 
which is a result from forage-fed systems.  A drive for forage-fed beef production has 
been created by the rapid increase in the world?s human population.  This population 
increase could possibly create a shortage in the supply of grain worldwide, thus creating 
an importance for grass or forage production systems (Reverte et al., 2003).   
 The southeastern United States is a region that has optimum conditions for a year-
round forage production system (Cox, 2004; Sapp et al., 1999).  In the United States, 
consumers demand products that are developed from an array of specialty areas (Braden, 
2006; Resurreccion, 2003) such as forage-finished beef which is now a leading niche 
market (Braden, 2006; Prevatt et al., 2006). Since today?s consumers are interested in 
72 
convenient, heat-and-eat products the beef industry is in competition with the poultry 
industry that already has several convenience products available to consumers.  The beef 
industry has been able to meet consumers? needs by providing them with a safe yet 
flavorful product.   
 To meet the growing demands for beef, the beef industry and researchers have 
been working on improving shelf-life stability and palatability of forage-fed beef to 
provide a longer-lasting product for the niche market.  Since forage?fed beef naturally 
contains more vitamin E than grain-fed beef it is possible that the beef will naturally 
improve oxidative stability, enhance color retention, and increase retail shelf life offering 
an opportunity for ?value added? consumer products with enhanced nutrient value 
according to Decker et al. (2000).  Animals finished on forage diets have been noted to 
provide acceptable carcass weights and degrees of finish when finished at a young age 
(Muir et al., 1998a).  This study also showed that acceptable quality characteristics can be 
achieved by a forage-finishing system when compared to a grain-based diet.   
 Several studies have been conducted on forage-fed beef and in some cases are 
known to improve the color stability of the product (Arnold et al., 1992).  A problem 
faced with forage-fed beef is that it has several off flavors such as grassy, rancid, livery, 
and metallic.  Enhancing forage-fed beef with a beef flavoring agent in a salt/phosphate 
solution has been noted to decrease the intensity of the off flavors. 
 Modified atmospheres are being used more widely to assist in the shelf-life of the 
product (Jakobsen and Bertelsen, 2000).  Atmospheres that promote the blooming of 
color pigments may not always be safe because consumers determine meat quality based 
on color.  According to Zhao et al. (1994) lipid oxidation occurs at a slower rate than the 
73 
deterioration of the color pigments.  An elevated oxygen level is known to extend color 
stability, but the increased rate of oxidation can also be expected (Zhao et al., 1994).    In 
the CO packaging, a pigment known as carboxymyoglobin is formed (Lanier et al., 
1978).  The carboxymyoglobin is similar to the bright red oxymyoglobin pigment that is 
formed at the surface of fresh meat in air.  Carboxymyoglobin is known to less readily 
oxidize to brown metmyoglobin than is oxymyoglobin because of the strong binding of 
CO to the iron site on the myoglobin molecule (Lanier et al., 1978).  Results from 
Sorheim et al. (1999) show that a low CO/high CO
2
 atmosphere is effective for 
preserving retail-retail meats. 
 Objectives of this study were to determine if the percent of grass-fed and grain-
fed beef trim and modified atmosphere would improve the quality and shelf-life stability 
of ground beef.  Organoleptic factors were also studied to determine if the grass-fed beef 
trim produced off flavors commonly associated with grass-fed beef. 
MATERIALS AND METHODS 
Sample Collection and Preparation 
 Eighteen kilograms of grass-fed beef trim from fall-born Angus x Continental 
crossbred steers was ground through a 4.8 mm plate and fat analysis run using the Univex 
Fat Analyzer (Model FA73 Salem, NH).  Fat percent was formulated and re-ground to be 
approximately 20%.  It took 4 runs through the grinder to achieve the desired percent fat 
in the product.  This same procedure was performed using 18 kg of grain-fed beef trim.  
Percent fat was achieved in two grinds but since the grass-fed beef trim took 4 grinds, the 
grain-fed trim was ground two more times to equal the same number of grinds as the 
grass-fed beef trim.  Once fat percent was finalized the two ground beef feeding 
74 
treatments were mixed by hand in edible white lugs and then mixed (30 revolutions) 
using a table top hand mixer to produce mixtures of 0/100, 20/80, 40/60, 60/40, 80/20, 
100/0 respectively for grass-fed ground beef / grain-fed ground beef.  A 454 g batch was 
taken from each percentage mixture and placed in one of four packaging treatments: high 
oxygen (HO; 80% O
2
/20% CO
2
), low oxygen (LO; 65% N
2
/35% CO
2
), carbon monoxide 
(CO; 65% N
2
/34.6% CO
2
/0.4% CO; Koch ILPRA Model FoodPack 400V/G, Corso 
Pavia, Italy), or overwrap (OV).  This procedure was replicated two more times to assure 
proper packaging techniques and for use in retail display, sensory, and TBARS analyses.  
A replication of this entire process (Run 1) was repeated the following day (Run 2).  All 
packages were labeled for appropriate run and packaging treatment.  Fresh samples and 
18 h samples were collected to use as controls.  Eighteen hour samples (114g) were 
collected from the overwrap packages and then re-wrapped.   
 Initial and Retail Display Color Measurements 
Before packaging, an initial color measurement for CIE lean values for 
L*(lightness), a* (redness), and b* (yellowness) were recorded utilizing a Hunter 
Miniscan XE Plus (Hunter Laboratories Model 45/0-L, Reston, VA) with a illuminant 
D65 at a 10? observation angle and a 3.5-cm aperture.  Readings for lean color were 
taken from two readings on the anterior face of the ground beef and averaged to obtain a 
representation of the initial lean color.  Reflectance spectra values for the initial lean 
color were also determined.  Spectral reflectance values were determined at 520-, 530-, 
570-, and 580-nm and interpolated to determine the values for 525-nm and 572-nm 
respectively.  Readings for L*, a*, b*, 525 nm and 572 nm reflectance values for lean 
75 
color were taken from two readings on the anterior face of the ground beef and averaged 
to obtain a representation of the initial lean color.   
On d 1 of the retail display, the CIE lean color values (L*, a*, b*) was measured 
from each overwrap titration.  Each overwrap package was divided into two 227g 
samples, separately vacuumed packaged and frozen at -20?C for sensory and TBARS 
analyses.  Post retail color measurements from the remaining packages were taken on d 5 
of the display.  A Hunter Miniscan XE Plus (Hunter Laboratories Model 45/0-L, Reston, 
VA) with a illuminant D65 at 10? and a 3.5-cm aperture was used to measure the CIE 
lean values for L*(lightness), a* (redness), and b* (yellowness) values and spectral 
reflectance values were determined at 520-, 530-, 570-, and 580-nm and averaged to 
determine the values for 525-nm and 572-nm respectively.  The remaining ground beef 
samples were vacuumed packaged and frozen at -20?C until sensory and TBARS 
analyses. 
Storage and Retail Display 
Ground beef packages were stored for 5 d dark storage at 2?C.  The packages 
were checked 48 h post packaging and noted for leakers. The ground beef packages were 
placed in a Tyler (Model DMG-8, Niles, MI) retail display case at 2?C for retail panel 
analysis for 5 d.  The illumination intensity was 800lx at the surface of the package, 
utilizing Sylvania
?
 Designer Cool White Plus bulbs (F40/DCWP).   Six trained panelist 
rated ground beef packages for color, surface discoloration, and browning.  Color was 
based on an 8 point hedonic scale; 1 equaling extremely dark red and 8 equaling 
extremely bright cherry-red.  A 7 point hedonic scale was used for surface discoloration; 
1 equaling zero percent discoloration and 7 equaling 100 percent discoloration on 
76 
surface.  Browning was based on a 5 point hedonic scale; 1 equaling none and 5 equaling 
dark brown.   
Sensory 
 Ground beef samples (approximately 150 g and formed with a basic kitchen 
hamburger patty press) for sensory were thawed (4?C for 12-18h), weighed, and placed in 
a pre-heated George Foreman clam-shell-style grill (Model GRV120, Macon, MO) for 8 
min(Kerth et al., 2007), resulting in a final internal temperature of 76?C (AMSA, 1995).  
Cooked patties were weighed to determine the percentage cooking loss by dividing the 
weight lost during cooking by the pre-cooked weight.  Patties were divided using an 
apple cutter which produced eight pie-shaped samples and then placed in double broilers, 
with warm sand, until served to a six-member trained sensory panel.  In a cubicle 
supplied with red light, each of the trained panel members evaluated one sample from 
each ground beef patty and noted opinion on the evaluation form.  Panel members were 
asked to take a bit of a salt-free saltine cracker and sip water to aid in cleansing the palate 
and expectorate the sample in the cup provided.  An eight-point scale was used for the 
evaluations of initial and sustained juiciness, cohesiveness, flavor intensity, and off flavor 
(1= extremely dry, extremely crumbly, extremely bland, no off flavor to 8= extremely 
juicy, extremely cohesive, extremely intense beef, and extreme off flavor).  Panelists 
noted appropriate off flavor descriptors provided on form if scores were noted for an off 
flavor.   
Determination of Lipid Oxidative Stability 
 Lipid oxidative stability was analyzed by using the thiobarbituric acid (TBA) 
reactive substance assay modified from Buege and Aust (1978). Ground beef samples 
77 
used for lipid oxidative stability were removed from frozen storage and a 5-g sample was 
homogenized with 15 mL of distilled water.  Approximately 4 mL homogenate was 
combined with 8 mL of trichloracetic/thiobarbituric acid reagent and 200 .notdef.g0002L of 10% 
butylatedhydroxyanisole.  Samples were incubated in a 99?C water bath for 15 min, 
allowed to cool in cold water for 10 min, and filtered through Whatman paper.  The 
absorbance of the samples was read against a blank containing like reagents at 531 nm.  
Malonaldehyde standards were constructed utilizing 1, 1, 3, 3-tetraethoxypropane and 
thiobarbituric acid reactive substances were reported as mg/5g of meat.  
Statistical Analysis 
 Data for sensory, cook-loss, off descriptors, and TBA was analyzed as a 6 (0/100, 
20/80, 40/60, 60/40, 80/20, 100/0, grass/grain diet) by 4 (CO, HO, LO, or VAC 
packaging) factorial arrangement of a completely randomized design using GLM 
procedure of SAS.  Run had no significant effect (P > 0.10) and was not included in the 
analyses.  Significant (P .notdef.g0001 0.05) main and interaction effect means were separated with 
Fisher?s protected LSD using the PDIFF option of LSMEANS in SAS.  For retail display 
data, the effect of day was analyzed as a repeated measure using the replication within 
packaging and grass/grain titration as the error term for packaging, grass/grain, and their 
interaction, and the residual error to test for day and day interaction effects.  The effect of 
the two runs was tested and found to not be a significant (P> 0.10) source of variation, so 
data for the runs was pooled together for analyses. 
 
 
 
78 
RESULTS 
Initial Color 
At the fresh or initial recordings for CIE L* before packaging, there was no 
difference (P > 0.05) in the MAP (Figure 4.2).  The titrations for 20/40, 40/60, and 60/40 
had higher (P < 0.05) L* values than the other grass/grain titrations.  At the beginning of 
the retail display (d 2) all MAPs and titrations had decreased (P < 0.05) in L* values.  
The 100/0 titration was the lowest (P < 0.05) within the HO for d 2.  At the end of the 
retail display, the 100/0 titration had the highest (P < 0.05) value for L* within the OV. 
 All a* values taken on d 1 (fresh) showed no difference (P > 0.05) for the 
titrations and MAPs (Figure 4.3).  At the beginning of the retail display, the CO had the 
highest (P < 0.05) a* values over all other MAP.  The 0/100 had the lowest (P < 0.05) a* 
value within the OV at the beginning of retail display.  By the end of the retail display, 
the CO still had the highest (P < 0.05) a* values over all other MAP.  The 100/0 had the 
highest (P < 0.05) a* values than all other titrations at the end of the retail display within 
all MAPs.   
 The MAP*Day interaction for b* was significant (P < 0.05) therefore showing 
that the b* values decreased for all MAP as the retail display lengthened (Figure 4.4).  
The titrations for 0/100, 80/20, and 100/0 had the highest (P < 0.05) b* values on d 1.  At 
the beginning of the retail display, some b* values increased (P < 0.05) while others 
decreased (P < 0.05), but by the end of the retail display the 100/0 titration was the 
highest (P > 0.05) for b* values within all MAP.    
 On d 1, there were no differences (P > 0.05) in the MAP and grass/grain titrations 
for metmyoglobin instrumental values (Figure 4.5).  At the beginning of retail and end of 
79 
retail display, the CO had the lowest (P < 0.05) metmyoglobin values.  The beginning of 
retail display, 0/100 had the highest (P > 0.05) metmyoglobin values within the OV.  At 
the end of the retail display, the 100/0 had the lowest (P < 0.05) metmyoglobin values.  
This means that there was less browning within the 100/0 titration when compared to the 
other titrations.  The CO packaging represented the least (P < 0.05) browning over all 
other MAP.  
 The values for the hue angle showed no difference (P > 0.05) for the fresh 
samples for both the titrations and MAP (Figure 4.6).  The CO had the lowest (P < 0.05) 
hue value for the beginning and end of retail display.  The 0/100 had the highest (P < 
0.05) hue values within the OV for the beginning and end of the retail display.   
 There was no difference (P > 0.05) in chroma values between the MAP and 
grass/grain titrations for the fresh samples (Figure 4.7).  The CO remained relatively 
constant at the beginning or d 2 of the retail display while the other MAP had decreased 
(P < 0.05) in chroma values.  The 100/0 had the highest (P > 0.05) chroma values for all 
days of the retail display except for d 2 or the beginning of retail display within the HO. 
Sensory 
  A significant difference (P < 0.05) was noted in the grass/grain titrations for 
initial and sustained juiciness (Table 4.1).  A decrease in initial and sustained  juiciness  
(P < 0.05) was noted when 40/60 was compared with 60/40, 0/100 and 100/0; but no 
difference (P > 0.05) was noted when compared to 20/80 and 80/20.  A decrease (P < 
0.05) in intial juiciness score was noted for 20/80 when compared to 100/0, but no 
significant difference (P > 0.05) when compared with 0/100, 40/60, 60/40, and 80/20.  
The titration for 60/40 was not significantly different (P > 0.05) from any of the other 
80 
titrations for initial juiciness.  For sustained juiciness, 40/60 was significantly different (P 
< 0.05) from 0/100, 100/0, and 60/40 (increased or decreased in sustained juiciness 
depending on the MAP); 100/0 was significantly different (P < 0.05) when compared 
with 20/80 and 80/20.  The grass/grain titration did not show a significant difference (P > 
0.05) in the remaining sensory characteristics for cohesiveness, flavor intensity, and off 
flavor.  The modified atmosphere packaging was not significant (P > 0.05) for any of the 
sensory characteristics or cook-loss.  There was no significant difference (P > 0.05) when 
the MAP and grass/grain titrations were combined.  
Off Flavor  
The CO packaging noted to have a less (P < 0.05) grassy off flavor than the 
overwrap packaging (Figure 4.1).  Other off flavors were noted by the sensory panel to 
have characteristics of rancid, bloody, bitter, livery, salty, metallic, and other (data not 
shown).   
Retail shelf-life  
The CO had shown an extremely bright cherry-red visual lean color for all days of 
the retail display when compared with other MAP (P < 0.05); Figure 4.8).  Visual lean 
discoloration was noted the least (P < 0.05) in the CO for all days of retail display.  The 
OV had the highest (P < 0.05) discoloration scores by day 3 and day 5 (Figure 4.9).  
Browning occurred the most in the OV for all days of display (P < 0.05; Figure 4.10).  
The least browning (P < 0.05) was seen in the CO.  The visual browning within the OV 
supports the high metmyoglobin values seen within the OV. 
 
 
81 
Lipid oxidation 
Overall the HO package seemed to have the most (P < 0.05) thiobarbituric 
reactive substance values (TBARS; Figure 4.11).  Even though there was no significant 
difference (P > 0.05) in the MAP*grass interaction, the 0/100 had the highest TBARS 
values within the LO and OV. 
DISCUSSION 
Initial Color 
 Color values for the titrations with the most grass content were not significant (P 
> 0.05) when compared with the titrations with the most grain content.  All ground beef 
packaged in CO was bright red and had low hue values.  The study by John et al. (2004) 
agrees with the present study pertaining to high a* (redness) values and low hue angle 
values that represent redness within the CO package. The redness value (a*) was 
maintained better in the MAP than the OV according to Houben et al. (2000) which also 
agrees with the present study that color was best retained in the MAP packaging.  By the 
end of the retail display HO had lost its initial bright red color as indicated by increased 
hue angle values as well as a* values decreased and visual scores reported a decrease in 
red color (P < 0.05).  Sorheim et al. (1999) agree with the present study in that their HO 
package (70% O
2
/30% CO
2
) resulted with an initial bright red to re color, but the color 
was unstable and off-odors developed rapidly.   
Sensory 
 Forage-fed beef is noted by several researchers to have lower juiciness scores 
when compared to grain-fed beef (Hedrick et al., 1983; Sapp et al., 1999).  There are 
several researchers such as Cross et al. (1978) and Bidner et al, (1981b) that reported no 
82 
differences in juiciness between the two feeding systems.  In the present study for ground 
beef as the titrations increase from 0/100 to 100/0 the initial and sustained juiciness 
scores decreased (P < 0.05).  When comparing forage-fed cattle and grain-fed cattle, 
forage-fed cattle are known to have a less desirable flavor than cattle finished on grain 
(Wanderstock and Miller, 1948; Kropf et al., 1975; Bowling et al., 1977).  In the present 
study there was no difference in off flavor (P > 0.05) for the grass/grain titrations.  
Majority of the 100/0 titrations noted a higher flavor intensity score than the 0/100 
titrations but there was no significance (P > 0.05). 
Off Flavor  
Ground beef from forage-fed beef is known to result in a more intense flavor 
(negative rating; Bagley and Feazel, 1987).  Flavor is normally associated with the fat 
content of the product and ground beef has a much higher fat percent than steaks (up to 
30%).  The higher amounts of grass in the ground beef samples from the present study is 
supported by Melton et al. (1982) as being less desirable in flavor with an intense dairy-
milky flavor and often a soured or other off-flavor.  In the present study and the study by 
Melton et al. (1982) all ground beef had the same amount of fat percentage (19.5) and 
this was not believed to be the cause of flavor differences.   
Retail shelf-life  
 The visual lean color scores in the present study indicated that CO package 
maintained the bright, cherry-red color best over all other MAP.  Hunt et al. (2004) stated 
that the addition of CO to the package formed a bright red carboxymyoglobin color when 
CO binds to myoglobin (Sorheim et al., 1999) and may be more stable (less likely to 
discolor to metmyoglobin) during retail display than the traditional packages that have 
83 
oxymyoglobin formation.  This statement by Hunt et al. (2004) supports the findings in 
the present study.   The titrations with the most grass percentage tended to have more 
positive results when compared to the high grain titrations.  Data from O?Sullivan et al. 
(2004) supports that higher vitamin E levels (grass) increases color stability and improves 
oxidative and color stability.  Leakers (packages that had not sealed well or had holes in 
the trays) were noted in several MAP packages that may result in lower shelf-life, 
sensory, and TBARS scores because the modified atmosphere was not maintained. 
Lipid oxidation 
 Lipid oxidation was lower (P < 0.05) for the titrations with the most percentage 
being grass.  This demonstrates the antioxidant effect of Vitamin E.  The Houben et al. 
(2000) study agrees with the present study that higher the amounts of grass percentage, 
the less lipid oxidation.  The Houben et al. (2000) study also stated that the modified 
atmosphere package (65% O
2
/25% CO
2
/10% N
2
) resulted with higher lipid oxidation 
values than the foil overwrapped trays in minced beef.  The present study did not use the 
same gas mixtures as Houben et al. (2000), but oxidation was noted more in the HO and 
OV when compared to the CO and LO.   
IMPLICATIONS 
Implications of this study were to determine how much (0, 20, 40, 60, 80, 100%) 
grass-fed beef trim is needed to be added to the mixture to achieve the antioxidant 
properties and color stability that is provided from the vitamin E, while at the same time 
adding grain-fed beef trim to maintain a positive flavor.  Modified atmosphere packages 
were used to help stabilize color and extend shelf-life of the ground beef.  The packages 
with the higher grass concentrations and CO gas results were the best for color.   
84!
Table 4.1.  Least Square Means ? SEM of Sensory Ground Beef patties from different 
MAP packaging treatments and six grass/grain titrations 
a
5=slightly juicy, 6=moderately juicy. 
b
5=slightly cohesive, 6=moderately cohesive. 
c
5=slightly intense bef, 6=moderately intense bef. 
d
5=moderate of flavor, 6=very of flavor. 
e
CO=Carbon monoxide packaging, HO=High Oxygen packaging, LO=Low oxygen packaging, OV=Over 
wrap packaging. 
f
0/10=0% gras and 10% grain, 20/80=20% gras and 80% grain, 40/60=40% gras and 60% grain, 
60/40=60% gras and 40% grain, 80/20=80% gras and 20% grain, 10/0=10% gras and 0% grain. 
g,h,i 
Means in a column for the diet main efect with diferent superscripts difer (P < 0.05)!
 In. 
Juicines
a 
Sus. 
Juicines
a 
Cohesivenes
b 
Flav. 
Intensity
c 
Of 
Flavor
d 
Coklos 
CO
e 
      
0/10
f 
5.58
hi 
5.0
hi 
4.17
 
5.0 1.92 28.6 
20/80 5.17
gh
 4.83
gh
 4.0 5.42 2.75 30.7 
40/60 5.34
g
 5.17
g
 3.84 5.83 1.59 29.3 
60/40 5.59
hi 
5.3
hi
 3.75 5.25 2.17 26.8 
80/20 5.59
ghi
 5.42
gh 
4.0 5.50 1.92 26.7 
10/0 
 
5.50
i
 5.17
i
 4.42 5.92 1.42 29.3 
HO       
0/10 5.34 5.25 4.08 5.75 1.75 24.8 
20/80 6.09
 
5.75 4.0
 
 5.50 2.09 2.4 
40/60 6.34
 
5.75 3.67 5.50 2.09 24.7 
60/40 5.34 4.83 3.50 5.34 3.3 28.0 
80/20 5.42 5.17 4.59 5.50 1.67 26.8 
10/0 
 
5.50 4.92 3.67 5.34 3.09 28.1 
LO       
0/10 5.67
 
5.25 4.0 5.25 2.75 26.9 
20/80 6.09 5.67 3.75 5.42 2.92 24.5 
40/60 6.25 5.83 3.67 5.34 2.75 21.6 
60/40 5.50
 
5.08 3.75 5.42 2.67 27.9 
80/20 5.08 5.0 4.3 5.3 2.09 29.3 
10/0 
 
4.3 4.0 3.92 5.34 1.42 31.4 
OV       
0/10 4.59 4.25 4.17 5.08 2.67 30.7 
20/80 5.34 5.25 4.17 5.17 3.0 26.9 
40/60 5.58 5.59 3.75 5.09 3.42 26.8 
60/40 5.0 4.84 4.34 5.25 2.42 29.8 
80/20 5.75
 
 
5.42 4.25 5.17 2.92 27.3 
10/0 
 
5.09 4.83
 
3.67 
 
 
 
5.42 2.75 30.8 
SEM 0.321 0.37 0.367 0.302 0.828 2.984 
P > F       
diet 0.032 0.02 0.35 0.91 0.89 0.41 
MAP 
 
0.15 0.65 0.85 0.31 0.3 0.30 
diet*MAP 0.08 0.27 
 
0.94 0.92 0.94 0.90 
!
85 
Figure 
4.
1
.  
Least square means ? SEM for ground b
eef 
for 
grassy
 
off descriptor 
as a percent frequency.
 M = modified 
atmosphere packaging, G = grass/grain, CO= Carbon monoxide, LO= Low oxygen, HO= High oxygen, 
OV
= 
Overwrap
 
! !
0 5 
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 
 % Frequency 
M = 0.01, G = 0.60, M*G = 0.95   
CO 
LO 
HO  
OV
 
!
86 
Figure 
4.
2
.
  Least square means ? SEM for CIE L* instrumental values of ground beef by grass/grain titrations at the beginning 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon mono
xide, LO = Low oxygen, HO = High oxygen, OV = overwrap packaging; 
1
CIE L* Value 
(increasing value indicates a lighter color). Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of retail.
 
 
!
0 5 
10 15 20 25 30 35 40 45 50 55 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
CIE L* Value
 
M = 0.07, G = 0.003, D = 0.001, M*G = 0.15, M*D = 0.001, G*D = 0.04, M*G*D = 0.001 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
!
87 
Figure 
4.
3
.  Le
ast square means ? SEM 
for CIE a
* instrumental values of ground beef by grass/grain titrations at the beginning 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO =
 High oxygen, OV = overwrap packaging; 
1
CIE a
* Value 
(
positive = red, 0 = neutral, negative = green)
. Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of retail.
 
 
 
!
0 5 
10 15 20 25 30 35 40 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
CIE a* Value
 
M = 0.001, G = 0.12, D = 0.001, M*G = 1.00, M*D = 0.001, G*D = 0.001, M*G*D = 0.03 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
!
88 
Figure 
4.
4
.  Le
ast square means ? SEM for CIE b
* instrumental values of ground beef by grass/grain titrations at the beginning 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxy
gen, OV = overwrap packaging; 
1
CIE b
* Value 
(
positive = yellow, 0 = neutral, negative = blue
)
. Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of retail.
 
 
 
!
0 5 
10 15 20 25 30 35 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
CIE b* Value
 
M = 0.28, G = 0.35, D = 0.001, M*G = 1.00, M*D = 0.002, G*D = 0.001, M*G*D = 0.29 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
!
89 
Figure 
4.
5
.  Le
ast square means ? SEM for 
metmyoglobin
 instrumental values of ground beef by grass/grain titrations at the 
beginning and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxyg
en, OV = overwrap packaging; 
1
Metmyoglobin percentage (oxidized myoglobin pigment).
 Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of 
retail.
 
 
 
!
25 35 45 55 65 75 85 95 
105 1
15 
125 135 145 155 165 175 185 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
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?!
"#
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"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
Metmyoglobin, %
 
M = 0.001, G = 0.04, D = 0.001, M*G = 0.74, M*D = 0.001, G*D = 0.001, M*G*D = 0.21 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
!
90 
Figure 
4.
6
.  Le
ast square means ? SEM for 
Hue
 instrumental values of ground beef by grass/grain titrations at the beginning and 
end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxyg
en, OV = overwrap packaging; 
1
 Hue value 
(
numerically 
decreasing
 true red color
).
 Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of retail.
 
 
 
!
20 25 30 35 40 45 50 55 60 65 70 75 80 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
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?!
"#
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"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
 Hue Values
 
M = 0.001, G = 0.17, D = 0.001, M*G = 0.66, M*D = 0.001, G*D = 0.001, M*G*D = 0.02 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
! !
91 
Figure 
4.
7
.  Le
ast square means ? SEM for 
Chroma
 instrumental values of ground beef by grass/grain titrations at the beginning 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxyg
en, OV = overwrap packaging; 
1
 
Chroma
 value 
(
numerically increasing 
color saturation
).
 Day 1 = Fresh, Day 2 = beginning of retail, Day 5 = end of retail.
 
 
!
0 5 
10 15 20 25 30 35 40 45 50 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
 Chroma Values
 
M = 0.001, G = 0.23, D = 0.001, M*G = 1.00, M*D = 0.001, G*D = 0.001, M*G*D = 0.08 
-./0
#11%--./0
#23!
+-./0
#114-./0
#23!
5-./0
#116-./0
#23!
6-./0
#115-./0
#23!
4-./0
#11+-./0
#23!
%--./0
#11-./0
#23!
! !
92 
Figure 
4.
8
.  Le
ast square means ? SEM for 
visual lean color
 of ground beef by grass/gr
ain titrations at the beginning, middle 
and 
end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxygen, OV = overwrap packaging; 
1
 Lean color
 
(
1 = extremely 
dark red; 8 = 
extremely bright cherry
-
red
).
 
 
!
0 1 2 3 4 5 6 7 8 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
 Visual Lean Color Score
 
M = 0.001, G = 0.07, D = 0.001, M*G = 0.20, M*D = 0.001, G*D = 0.63, M*G*D = 0.86 
-./0
#11%--./0
#23!
4-./0
#115-./0
#23!
6-./0
#117-./0
#23!
7-./0
#116-./0
#23!
5-./0
#114-./0
#23!
%--./0
#11-./0
#23!
! !
93 
Figure 
4.
9
.  Le
ast square means ? SEM for 
visual lean 
discoloration
 of ground beef by grass/gr
ain titrations at the beginning, 
middle 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of retail 
display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxygen, OV = overwrap packaging; 
1
 Lean 
dis
color
ation
 
(
1 = 
none
; 
7
 = 
total discolor
ation
).
 
 
!
0 1 2 3 4 5 6 7 8 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
 Visual Lean Discoloration Score
 
M = 0.001, G = 0.25, D = 0.001, M*G = 0.55, M*D = 0.001, G*D = 0.22, M*G*D = 0.16 
-./0
#11%--./0
#23!
4-./0
#115-./0
#23!
6-./0
#117-./0
#23!
7-./0
#116-./0
#23!
5-./0
#114-./0
#23!
%--./0
#11-./0
#23!
! !
94 
Figure 
4.
1
0
.  Le
ast square means ? SEM for 
visual lean 
browning
 of ground beef by grass/gr
ain titrations at the beginning, 
middle 
and end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, D = day of 
retail display. CO = Carbon monoxide, LO = Low oxygen, HO = High oxygen, OV = overwrap packaging; 
1
 Lean 
browning 
(
1 = 
none
; 
5
 = 
dark brown
).
 
 
!
0 1 2 3 4 5 
"#
$!%!&
?!
"#
$!%!(?!
"#
$!%!)
?!
"#
$!%!?
*!
"#
$!+!&
?!
"#
$!+!(?!
"#
$!+!)
?!
"#
$!+!?
*!
"#
$!,!&
?!
"#
$!,!(?!
"#
$!,!)
?!
"#
$!,!?
*!
1
 Visual Lean Browning Score
 
M = 0.001, G = 0.12, D = 0.001, M*G = 0.80, M*D = 0.001, G*D = 0.76, M*G*D = 0.93 
-./0
#11%--./0
#23!
4-./0
#115-./0
#23!
6-./0
#117-./0
#23!
7-./0
#116-./0
#23!
5-./0
#114-./0
#23!
%--./0
#11-./0
#23!
! !
95 
Figure 
4.
1
.  Le
ast square means ? SEM for 
thiobarbituric reactive substance values
 of ground beef by grass/gr
ain titrations 
at the
 
end of retail display for MAP. M = modified atmosphere packaging, G = grass/grain titration, CO = 
Carbon monoxide, 
LO = Low oxygen, HO = High oxygen, OV = overwrap packaging
 
 
!
0 
0.5 
1 
1.5 
2 
2.5 
3 
3.5 
4 
4.5 
5 
5.5 
6 
6.5 
7 
7.5 
8 
8.5 
9 
9.5 
10 
"
#!
$#!
%
#!
#
&!
Thiobarbituric Reactive Substances Values, mg/kg 
M = 0.002, G = 0.02, M*G = 0.99 
?()*
+,,-??()*
+./!
0?()*
+,,1?()*
+./!
2?()*
+,,3?()*
+./!
3?()*
+,,2?()*
+./!
1?()*
+,,0?()*
+./!
-??()*
+,,?()*
+./!
96 
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110 
 
APPENDICES 
111 
APPENDIX A 
 
Retail Display Shelf-Life Visual Evaluation Setup 
 
1. Obtain desired pumped or non-pumped fabricated 2.54cm cuts from harvest 
facility, package in MAP or vacuum package accordingly and store at 2 C for 21d. 
 
2. Select postmortem days so that the first of each postmortem period fall on the first 
of the week. 
 
3. At each postmortem period steaks should be placed in to simulated retail 
conditions. 
 
4. In this study a Tyler (Model DMG-8, Niles, MI) retail display case (coffin) were 
utilized. 
 
5. Steaks should be allowed to remain in retail display case at 2 C for 5 days and 
should be subjected to 24h exposure to retail display lighting (illumination 
intensity at surface of the steaks should be near 1,000 lx). 
 
6. During each 5 day postmortem period steaks should be evaluated by a trained 
panel, consisting of at least six members, for beef color, color uniformity, surface 
discoloration, and lean browning according to AMSA (1991) color guidelines. 
 
112 
APPENDIX B 
 
Instrumental Color Evaluation 
1. Obtain desired pumped or non-pumped fabricated 2.54cm cuts from harvest 
facility, package in MAP or vacuum package accordingly and store at 2 C for 21d. 
 
2. Prior to packaging the Commission Internationale de l?Eclairage (CIE) L* 
(muscle lightness), a* (muscle redness), and b* (muscle yellowness) values were 
determined from two random reading on each steak with a Hunter Miniscan XE 
Plus (Hunter Laboratories Model 45/0-L, Reston, VA). 
 
3. Select postmortem days so that the first of each postmortem period fall on the first 
of the week. 
 
4. At each postmortem period steaks should be placed in to simulated retail 
conditions. 
 
5. In this study a Tyler (Model DMG-8, Niles, MI) retail display case (coffin) were 
utilized. 
 
6. Steaks should be allowed to remain in retail display case at 2 C for 5 days and 
should be subjected to 24h exposure to retail display lighting (illumination 
intensity at surface of the steaks should be near 1,000 lx). 
 
7. At the end of the 5d retail display the Commission Internationale de l?Eclairage 
(CIE) L* (muscle lightness), a* (muscle redness), and b* (muscle yellowness) 
values were determined from two random reading on each steak with a Hunter 
Miniscan XE Plus (Hunter Laboratories Model 45/0-L, Reston, VA). 
 
113 
APPENDIX C 
 
Sensory Evaluation 
1. Steaks should have an internal temperature of 2-5?C before cooking.  It is 
common to thaw steaks before cooking at 2-5?C for 12 hours. 
 
2. Take care and maintain sample identity throughout process. 
 
3. Pre-heat sample holding containers and pans.  Pans with separate suspended 
compartments can be utilized, with the addition of sand below to maintain 
temperature. 
 
4. Internal temperature of each steak should be taken in the geometric center of the 
steak and recorded.  Temperatures should be in the range of 2-5?C. 
 
5. Weigh each steak in grams before cooking and record. 
 
6. Place steak on cooking surface and cook until a medium degree of doneness.  The 
internal temperature of steaks should be approximately 71?C. 
 
7. Weight and temperature of each steak should be recorded immediately after 
cooking utilizing the same procedure as before cooking. 
 
8. Cut all four sides of the steak in a fashion that produces a square or rectangle out 
of the steak, while removing fat and connective tissue. 
 
9. Place all pieces of sample in designated sample holding containers and maintain 
identity. 
 
10. Panel room should be prepared before cooking to facilitate efficient panel time 
and minimize period after cooking until panel evaluations. 
 
11. Panel set-up and evaluations should be according to Cross et al., 1978. 
 
12. Record all sensory data for analysis. 
 
114 
APPENDIX D 
 
Thiobarbituric Reactive Substance (TBA) Assay 
Modified from: 
Buege and Aust. 1978. Methods in Enzymol. 52.302, AP 
Reagent: 
1. TCA/TBA stock solution: 15% TCA(w/v) and 20 mM TBA (MW 144.15) 
reagent in DW.  Dissolve 2.88g TBA in warm DDW first, add TCA 
(150g) and then add DW to the mark (1L).  Once liter last 100 samples 
in duplicate. 
 
2. BHA: Make 10% stock solution by dissolving in 90% ethanol. Make 
500ml batches. 
 
3. TEP standard: 1*10
.notdef.g00023 
M 1, 1, 3, 3-tetra-ethoxypropane in DW. This 
solution can be kept for about a week if stored in the refrigerator and 
diluted as needed. (MW 220.31, 95% purity, d=0.918). Dilute 0.5ml TEP 
with 499.5 ml DW, and dilute the resulting solution 1:2.96 (TEP solution: 
DW) with DW. 
Procedure: 
 
1. Slice 5g of fresh meat and place in blender cup with 15ml of DW. 
 
2. Homogenize with a blender for 2 min. (or homogenize for 10-15 sec using 
a polytron at speed 7-8). 
 
3. Take 2ml of the homogenate, combine with 4ml of the TCA/TBA reagent, 
100.notdef.g0001l BHA, vortex thoroughly. 
 
4. Heat the solution for 15 min in a boiling water bath. 
 
5. Cool for 10 min in a cold water bath. 
 
6. Vortex thoroughly. 
 
7. Centrifuge at 2000G (3000RPM) for 10 min or filter using Whatman 
paper. 
 
8. Read the absorbance of the supernatant at 531 nm against a blank that 
contains all the reagents minus sample. 
 
 
115 
 
 
Malonaldehyde standard curves (CHO-CH
2
-CHO, MW 72.0) 
 
1. Construct TBA standard curve using TEP. 
2. Label tubes: six tubes -0 and two tubes of each- 5, 10, 20, 30, 40, and 50. 
3. Add the following amounts to each tube: 
 
 TEP DW Set pipettor on: 
0 0.notdef.g0001l 2000.notdef.g0001l 1000 (twice) 
5 10.notdef.g0001l 1990.notdef.g0001l 995 (twice) 
10 20.notdef.g0001l 1980.notdef.g0001l 990 (twice) 
20 40.notdef.g0001l 1960.notdef.g0001l 980 (twice) 
30 60.notdef.g0001l 1940.notdef.g0001l 970 (twice) 
40 80.notdef.g0001l 1920.notdef.g0001l 960 (twice) 
50 100.notdef.g0001l 1900.notdef.g0001l 950 (twice) 
 
4. Add 4ml TBA/TCA to each tube, vortex. 
 
5. Heat the tubes in boiling water bath for 15 min. 
 
6. Cool in cool water bath for 20 min. 
 
7. Vortex. 
 
8. Read the optical density of the standard against a blank at the same 
wavelength (531 nm). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
APPENDIX E 
116 
 
GROUND BEEF TRAINED SENSORY EVALUATION FORM 
Name______________ Date____________ Time: ___________ Project______________ 
Sample  No 
Initial 
juiciness 
Sustained 
juiciness 
Cohesiveness 
Flavor 
intensity 
Off  
Flavor 
Off-flavor 
Descriptor 
 
      
       
       
       
       
       
       
       
 
Juiciness 
 
Cohesiveness 
 
Flavor intensity 
 
Off Flavor 
 
Off flavor 
Descriptors 
8=Extremely 
juicy 
8=Extremely 
cohesive 
8=Extremely intense 
beef 
8=Extreme off 
flavor 
8=Metallic 
7=Very juicy 7=Very 
cohesive 
7=Very intense beef 7=Intense off 
flavor 
7=Salty 
6=Moderately 
juicy 
6=Moderately 
cohesive 
6=Moderately 
intense beef 
6=Very off flavor 6=Livery 
5=Slightly 
juicy 
5=Slightly 
cohesive 
5=Slightly intense 
beef 
5=Moderate off 
flavor 
5=Grassy 
4=Slightly dry 4=Slightly 
crumbly 
4=Slightly bland 4=Modest off 
flavor 
4=Bitter 
3=Moderately 
dry 
3=Moderately 
crumbly 
3=Moderately bland 3=Small off flavor 3=Bloody 
2=Very dry 2=Very crumbly 2=Very bland 2=Slight off flavor 2=Rancid 
1=Extremely 
dry 
1=Extremely 
crumbly 
1=Extremely bland 1=No off flavor 1=Other ? 
Explain 
APPENDIX F 
117 
 
TRAINED SENSORY EVALUATION FORM 
Name______________ Date____________ Time: ___________ Project______________ 
Sample  No Initial 
juiciness 
Sustained 
juiciness 
Initial 
tenderness 
Sustained 
tenderness 
Flavor 
intensity 
Off  
Flavor 
Off 
Descriptor 
        
        
        
        
        
        
        
        
 
Juiciness 
 
Tenderness 
 
Flavor intensity 
 
Off Flavor 
 
Off flavor Descriptors 
8=Extremely 
juicy 
8=Extremely 
tender 
8=Extremely intense 
beef 
8=Extreme off 
flavor 
8=Metallic 
7=Very juicy 7=Very tender 7=Very intense beef 7=Intense off flavor 7=Salty 
6=Moderately 
juicy 
6=Moderately 
tender 
6=Moderately 
intense beef 
6=Very off flavor 6=Livery 
5=Slightly 
juicy 
5=Slightly 
tender 
5=Slightly intense 
beef 
5=Moderate off 
flavor 
5=Grassy 
4=Slightly dry 4=Slightly 
tough 
4=Slightly bland 4=Modest off 
flavor 
4=Bitter 
3=Moderately 
dry 
3=Moderately 
tough 
3=Moderately bland 3=Small off flavor 3=Bloody 
2=Very dry 2=Very tough 2=Very bland 2=Slight off flavor 2=Rancid 
1=Extremely 
dry 
1=Extremely 
tough 
1=Extremely bland 1=No off flavor 1=Other ? Explain 
APPENDIX G 
118 
 
Retail Display Shelf-Life Visual Evaluation 
 
Name: _________________________ Date: __________ Project: ________________ 
 
Beef color   Color Uniformity Surface discoloration Browning 
8=Extremely bright cherry-red 5=Extreme two-toning 7=100%   5=Dark brown 
7=Bright cherry-red  4=Moderate two-toning 6=80-99%  4=Brownish gray 
6=Moderately bright cherry-red 3=Small two-toning 5=60-79%  3=Grayish 
5=Slightly bright cherry-red 2=Slight two-toning 4=40-59%  2=Dull 
4=Slightly dark cherry-red  1=Uniform  3=20-39%  1=None 
3=Moderately dark cherry-red    2=10-19%   
2=Dark red      1=0%  
1=Extremely dark red 
 
No.   Color Uniform Discolor Brown No.  Color Uniform Discolor  Brown