Relationship of an Objective Measure and Consumer Perception of Oxidized Flavor in Ground Beef
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An experiment was conducted to compare the sensory and shelf life characteristics of ground beef with three different fat contents in order to determine if an objective measure is adequate in predicting consumer perception of rancidity in ground beef. Three different grinds, 73/27, 80/20, and 93/7, were packaged in overwrapped foam trays and put on retail display for 6 days. Starting on the day packages were placed on display (d 0), 5 packages from each grind were removed and frozen each day for further lab analysis. Also starting on d 0, 1 packaged from each grind was selected at random and color was evaluated daily with a Hunter Miniscan XE Plus. After completion of the retail display period, the frozen packages were thawed and samples were taken from each for evaluation of oxidative rancidity using TBARS and for sensory evaluation of juiciness (J), cohesiveness (CO), beef flavor (BF), off-flavor (OF), and cook loss (CL). Data were analyzed using the PROC GLM procedure of SAS. L* values were shown to increase with increasing fat percentage while a* values decreased. For days on display, all colorimetric values were found to decline within each grind. The 73/27 grind had the highest TBARS of 0.61, but this was not different from the other two grinds. Days 5 and 6 had the greatest values for TBARS (1.10 and 1.00 TBARS value, respectively), but were not different (P>0.05). Days 0 through 4 were not different from one another (P>0.05). Between grinds, differences were seen (P<0.05) in OF and CO. The 93/7 grind scored the most intense OF at 2.38. With regards to CO, the 73/27 grind had the greatest value of 5.55, but this was not different (P>0.05) from the 80/20 grind. No differences (P>0.05) in beef flavor were found among the three grinds. Throughout retail display, differences were also seen (P<0.05) in OF, CO, and BF. Days 5 and 6 had the most intense perceived OF but were not different (P>0.05) from one another. Day 0 had the least intense OF at 1.69, but was not different (P>0.05) than days 1 through 4. D 6 also had the most intense BF at 5.39, but was not different (P>0.05) than days 3, 4, or 5. Day 5 had the highest CO value at 5.52 and day 1 the least at 4.96. Days 0, 2, 3, 4, and 6 were not different (P>0.05) than either d 1 or 5. There was an interaction of grind and days of display on J and CL. The 73/27 grind had the highest J and CL values followed by the 80/20 and 93/7 grinds. Data indicates that factors beyond fat content play roles in ground beef color stability, lipid oxidation, and sensory characteristics. TBARS values were correlated with the OF values for each panelist resulting in an r value of 0.29, indicating a low correlation. Another variation of data analysis was performed in which the average of all panelists’ OF scores for each grind by day treatment was correlated to the TBARS for each treatment. This resulted in a higher correlation with an r value of 0.85. The TBARS and OF scores were also fitted to a regression and with all data together, the coefficient of determination was smaller (r2=0.05) than compared to the average of all panelists at r2=0.72. This shows TBARS can in some cases be used to predict consumer assessments of rancidity although there are numerous other factors that can influence the correlation.
- Megan McMurray Final Thesis.pdf