THE PRESENCE OF ESCHERICHIA-COLI, SALMONELLA AND CAMPYLOBACTER IN PIG CARCASS DEHAIRING EQUIPMENT

The total numbers of bacteria, and the numbers of Escherichia coli, Campylobacter and Salmonella were determined in the detritus accumulating in, and waters circulated through the pig carcass dehairing machines at two pig processing plants. The detritus from the machines at both plants yielded bacteria at total numbers between 8 × 107 and 9 × 108 cfu g-1, E. coli at numbers between 2 × 103 and 1 × 105 cfu g-1 and Campylobacter at numbers between 3 × 103 and 1 × 106 cfu g-1. Salmonella was recovered from about 50% of the samples at numbers between 3 × 103 and 4 × 105 cfu g-1 at plant A, and of 1 × 102 cfu g-1 at plant B. The waters in the two machines that are operated in series at plant A were at temperatures <50°C. Total numbers, numbers of E. coli, and numbers of Campylobacter in those waters were respectively between 2 × 105 and 1 × 106, 6 × 102 and 1 × 103 and 5 × 10 and 8 × 102 cfu ml-1. The temperature of the water in the machine at plant B was 57°C. Total numbers, and numbers of E. coli and Campylobacter in that water were respectively between 1 × 104 and 1 × 105, 1 × 103 and 5 × 103, and 1 × 10 and 5 × 102 cfu ml-1. Salmonella was recovered from about 50% of the water samples at both plants, at numbers between 1 × 10 and 6 × 102 ml-1 at plant A, and of 1 × 10 cfu ml-1 plant B. Carcasses leaving the second dehairing machine at plant A yielded total numbers, numbers of E. coli, and numbers of Campylobacter between 2 × 103 and 6 × 103, 9 × 10 and 9 × 102, and 3 and 7 × 10 cfu cm-2, respectively. The numbers similarly recovered at plant B were between 1 × 104 and 8 × 104, 4 × 102 and 4 × 103, and 1 and 4 cfu cm-2. After carcasses had been singed and polished, the total numbers recovered from carcasses were about 1 × 103 and 4 × 104 cfu cm-2 at plants A and B respectively. E. coli was at 1 or 2 cfu cm-2 on the polished carcasses at plant A, but at between 6 and 3 × 10 cfu cm-2 on those at plant B. Campylobacter was at between 1 and 6 cfu cm-2 on the polished carcasses at both plants. Salmonella was not recovered from the carcasses at either plant, at the detection level of 1 cfu cm-2. Clearly, the dehairing equipment at large slaughtering plants is a likely source of the mesophilic, enteric pathogens that commonly contaminate pork. © 1993 Academic Press Limited.