Assessment of the hygienic performance of a sheep carcass dressing process

Swab samples were obtained from the surfaces of randomly selected carcasses passing through a sheep carcass-dressing process. A single sample was obtained from a randomly selected site on the surface of each carcass. Twenty-five such samples were collected at each of four stages in the process. The aerobic bacteria, coliforms, and Escherichia coli recovered from each sample were enumerated. Values for the mean log and standard deviation of each set of 25 log(10) values were calculated on the assumption that the log values were normally distributed. The log of the arithmetic mean was estimated from the mean log and standard deviation values for each set. The results showed that bacteria, including coliforms that were largely E. coli, were deposited in high numbers during skinning operations, mainly on the butts and shoulders of carcasses. The mean numbers of coliforms and E. coli on carcasses were little affected by eviscerating and trimming operations, although they were redistributed from the sites they occupied after skinning. Total counts were redistributed and augmented by eviscerating and trimming operations. Washing reduced the log numbers of all of the bacteria by approximately 0.5. The general hygienic characteristics of the sheep carcass dressing process were similar to those of a previously examined beef carcass-dressing process.