Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 9, 1998
Publication Date: N/A
Interpretive Summary: This study determined the effect of lactic acid, acetic acid, trisodium phosphate, 162 deg F water, and 89 deg F water washes on bacteria placed on beef carcass surfaces after the carcass surfaces had been treated, before they were converted into ground beef. These effects were monitored during 21 days of refrigerated (38 deg F) or 3 days abusive (54 deg C) storage. Cattle feces containing low levels of Listeria innocua, Salmonella typhimurium, E. coli O157:H7, and Clostridium sporogenes was used to contaminate the carcass surface. In general, growth of these four bacteria, and total bacteria, was suppressed or not observed when lactic acid or acetic acid treatments were used. Bacteria introduced to treated beef surfaces after the tissue had received a trisodium phosphate treatment demonstrated satisfactory growth suppression. Water washes of 89 or 162 deg F offered little growth suppression of disease-causing bacteria during the cold storage period of the ground beef. The use of a final lactic or acetic acid wash during the processing of beef carcasses offers some long-lasting protection against growth of potentially harmful bacteria accidentally introduced into ground beef from the surfaces of carcasses contaminated after processing.
Technical Abstract: The effect of 2% (vol/vol) lactic acid (LA), 2% (vol/vol) acetic acid (AA), 12% (wt/vol) trisodium phosphate (TSP), 72 deg C water (HW), and 32 deg C water (W) washes on bacterial populations introduced to beef carcass surfaces post-treatment then converted to ground beef was determined up to 21 d at 4 deg C packaged storage. Beef carcass necks were collected from cattle immediately after harvest and subjected to the above treatments or untreated (C). Neck meat was then inoculated with low levels (ca.<2 log10) of Listeria innocua, Salmonella typhimurium, Escherichia coli O157:H7, and Clostridium sporogenes contained in a bovine fecal cocktail. In general, growth of these four bacteria, aerobic bacteria, lactic acid bacteria, and pseudomonads was suppressed or not observed in the ground beef when LA, AA, or TSP treatments were used when compared to the untreated control. HW or W washes offered little growth suppression of pathogens during subsequent storage of ground beef when these bacteria were introduced to beef tissue post-treatment. Of the treatments used, a final LA or AA wash during the processing of beef carcasses offers the best residual efficacy for suppression of pathogen proliferation in ground beef during long term refrigerated or short term abusive temperature storage, if these bacteria contaminate the carcass immediately after carcass processing.