Translocation of E. coli in Whole Muscle Non-Intact Beef
Type of Degreethesis
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Beef striploins were inoculated on the lean side with 8.2 to 10.1 log CFU/mL ranging from 6.4 to 7.2 mL of a nalidixic resistant Escherichia coli. Total CFU inoculated on striploins ranged from 1.12 X 109 to 9.10 X 1010. Striploins were passed once, lean side up, anterior end first, though a mechanical blade tenderizer. Subsequent uninoculated beef striploins (n = 5) were passed once, lean side up, anterior end first, through the same mechanical tenderizer following inoculated striploins. Six core samples were taken from each striploin starting with the anterior end and each core was cut into six segments. Segments 1 through 4 represented the top 4 cm and segments 5 and 6 represent the remaining portion split in half. Following tenderization, pathogen levels were highest (P <0.05) in loin 1. Loin 2 had higher (P < 0.05) levels than loins 4, 5, and 6. There were no differences (P > 0.05) between loins 3, 4, 5, and 6 which were below detectable limits. Levels of E. coli from segments 1 were higher than all other segments. Segment 2 had higher (P < 0.05) levels than 3, 4, 5, and 6. Pathogen recovery from segment 6 was higher (P < 0.05) than 3, 4, and 5. There were no differences (P > 0.05) between segments 3, 4, and 5. Data indicates that even with high initial inoculum numbers, contamination from one loin to another is quickly reduced to non-detectable levels.