Long-term bacterial profile of refrigerated ground beef made from carcass tissue, experimentally contaminated with pathogens and spoilage bacteria after hot water, alkaline, or organic acid washes

The effects of 2% (vol/vol) lactic acid (LA), 2% (vol/vol) acetic acid (AA) , 12% (wt/vol) trisodium phosphate (TSP), 72 degrees C water (HW), and 32 d egrees C water (W) washes on bacterial populations which were introduced on to beef carcass surfaces after wash treatments were determined up to 21 day s of storage at 4 degrees C of packaged ground beef prepared from the treat ed and inoculated carcasses. Beef carcass necks were collected from cattle immediately after harvest and subjected to the above treatments or left unt reated (control). Neck meat was then inoculated with low levels (ca. <2 log (10)) of Listeria innocua, Salmonella typhimurium, Escherichia coli O157:H7 , and Clostridium sporogenes contained in a bovine fecal cocktail. In gener al, 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 as compared to the untreated control. HW o r W washes offered little suppression of growth of pathogens during subsequ ent storage of ground beef when these bacteria were introduced onto beef ti ssue posttreatment. Of the treatments used, a final LA or AA wash during th e processing of beef carcasses offers the best residual efficacy for suppre ssion of pathogen proliferation in ground beef during long-term refrigerate d storage or short-term abusive temperature storage if these bacteria conta minate the carcass immediately after carcass processing.