MICROBIOLOGICAL EFFECTS OF ACID DECONTAMINATION OF BEEF CARCASSES AT VARIOUS LOCATIONS IN PROCESSING

Hot (55-degrees-C), dilute (1% v/v) lactic acid was sprayed on beef carcass surfaces immediately after dehiding, after evisceration (immediately before chilling), or at both locations. Surface samples of carcasses were examined for total aerobic plate counts (APCs) and for the presence of Salmonella and Listeria. APCs of treated beef carcasses were lower (P < 0.05) than those of control carcasses. APCs were determined both at slaughter day 0 (immediately after carcasses enter the chill room) and after 72 h postmortem. At day 0, reductions in log10 APC by more than 90% occurred when carcasses were treated with lactic acid after evisceration or both after dehiding and after evisceration. The effect of lactic acid decontamination was greatest on carcasses treated with lactic acid both after dehiding and after evisceration. No further reductions in APCs of carcasses were observed on samples taken 72 h postmortem. No difference in color between control and acid-treated carcasses was observed. All samples tested for the presence of Salmonella were negative. Listeria was detected in three samples from control carcasses only. Samples obtained from strip loins of acid-treated or control carcasses did not show any consistent pattern of differences in microbiological counts. Additional data collected from carcasses sprayed with lactic acid in three different sized slaughter plants showed that irrespective of differences in size of slaughter facility, mean APCs of acid-treated carcasses were significantly (P < 0.05) lower than those of control carcasses.