ANTIMICROBIAL EFFECTS OF TRISODIUM PHOSPHATE AGAINST BACTERIA ATTACHED TO BEEF TISSUE

Sliced beef tissue was artificially contaminated with Salmonella typhi murium, Listeria monocytogenes and Escherichia coli O157:H7. The conta minated tissue was immersed in 8, 10 and 12% solutions of trisodium ph osphate at 25, 40 and 55 degrees C with contact times of up to 3 min. The concentration of the trisodium phosphate solution was not a signif icant factor in reducing the populations of the bacteria on either lea n or adipose tissue. Reductions in bacterial populations of 1 to 1.5 l og(10) cycles were obtained on lean tissue contaminated with the gram- negative pathogens, although less reduction in population was seen wit h L. monocytogenes. Greater reductions in bacterial populations were o bserved on adipose tissue, with maximum reductions of 2 to 2.5 log(10) cycles and 1 to 1.5 log(10) cycles for the gram-negative and the gram -positive pathogens, respectively. Typically greater reductions in bac terial populations were seen as the temperature of the trisodium phosp hate solution increased. Surface beef carcass tissue was inoculated wi th E. coli ATCC 25922 and sanitized with 8% trisodium phosphate using a model carcass washing system. Population reductions with the carcass washer and lean tissue were comparable to those observed in the labor atory with E. coli O157:H7. However, greater reductions were observed on adipose tissue from the model system, suggesting that the physical washing procedure may have contributed to the reduction in the bacteri al population.