Changes in bacterial counts on beef carcasses at specific points during slaughter and fabrication were determined, and the effectiveness of nisin, lactic acid, and a combination of the lactic acid and nisin in reducing levels of microbiological contamination was assessed. Swab samples were obtained from the surfaces of randomly selected beef carcasses. Carcasses were swabbed from the neck, brisket, and renal site after skinning, splitting, and washing. Treatments involving lactic acid (1.5%), nisin (500 IU/ml), or a mixture of nisin and lactic acid were applied after the neck area was washed. A control group was not sprayed. Results indicated that the highest prevalence of aerobic plate counts (APCs), total coliforms, and Escherichia coli was found in the neck site after splitting, and the lowest level of microbial contamination was found after skinning. Washing with water did not significantly reduce the bacterial load. The largest reduction in APCs, total coliforms, and E. coli occurred on carcasses treated with a mixture of nisin and lactic acid. A mixture of nisin and lactic acid can be applied to beef carcasses through spray washing and can reduce bacterial populations by 2 log units.

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