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Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/19/2003 Publication Date: 6/1/2004 Citation: FLORES, R.A. ESCHERICHIA COLI O157:H7 DISTRIBUTION IN BEEF PROCESSED IN A TABLE-TOP BOWL-CUTTER. JOURNAL OF FOOD PROTECTION. 2004. V. 67. No. 2. pg 246-251. Interpretive Summary: Epidemiological studies show that foodborne illnesses caused by Escherichia coli O157:H7 have been associated with contaminated meat processing equipment. However, there is inadequate information about the effects of meat processing equipment on the distribution of E. coli O157:H7 in ground beef products. This study was designed to characterize the effects of a table-top bowl-cutter on the distribution of E. coli O157:H7 in ground beef when a single contaminated beef trim was introduced into a stream of uncontaminated beef trims. It was found that the bowl-cutter uniformly distributes the E. coli O157:H7 in the ground beef during the first minute of operation. The beef residues accumulated in the lid of the bowl-cutter, the knife-comb cover, and material spilled during operation were found to be contaminated with E. coli O157:H7. A batch of beef processed immediately after the batch contaminated with E. coli O157:H7 became contaminated. The contamination of the knife and bowl persisted after the second uncontaminated batch was processed. A probability distribution function for the mixing operation of E. coli O157:H7 in ground beef was determined and can be used in risk analysis models for the blending and mixing operations of beef products. Technical Abstract: Beef processing equipment can be contaminated with pathogens such as Escherichia coli O157:H7 and Salmonella spp. The bowl-cutter has wide application in particle-size reduction and blending of meat products. This study was undertaken to determine (1) the distribution patterns of E. coli O157:H7 in equipment components and ground beef produced with a table-top bowl-cutter, under different operational conditions; and (2) the likelihood that pathogen contamination can be transferred to subsequent batches, after a batch of beef contaminated with E. coli O157:H7 was processed in the same bowl-cutter. A beef trim inoculated with 2 log CFU of an E. coli O157:H7 strain resistant to rifampicin (E. coli O157:H7rif) was fed into an uncontaminated beef trim batch under two different batch sizes, three processing times, and two feeding modes. There were no significant differences (P is greater or equal than 0.05) among all the treatments for the averages of the normalized counts of E. coli O157:H7rif distributed in the ground beef. Regardless of the processing time and the method used to feed the beef trims into the bowl-cutter, the whole batch and at least the following subsequent batch, became contaminated when previously contaminated beef was processed. Areas of the bowl-cutter that were most likely to be contaminated with E. coli O157:H7 were (1) the material left on the top of the comb/knife guard, when testing beef residues, and (2) the knife, when swabbing the bowl-cutter surfaces. A Lognormal 2 probability distribution function was determined to describe the distribution of pathogenic organisms and can be applied when conducting process risk analyses on mixing-particle reduction operations for beef trims. |
