Does Spray Washing of Lamb Carcasses Alter Bacterial Surface Contamination?

Abstract

In order to ascertain clean slaughter and dressing procedures, the individual steps within the slaughter process have to be monitored for possible sources of contamination. In sheep slaughter those work processes in connection with skinning and evisceration have to be recognized as critical control points. In both the above areas of work, contamination of the carcasses does occur frequently. For the microbial assessment of postevisceration spray washing used frequently in line slaughter, 50 sheep carcasses were sampled, using replicate organism direct agar contact plates and swabs. A total of 900 tests were performed for total aerobic plate counts and for Enterobacteriaceae. Sampling commenced immediately after skinning, using the following sites: dorsal site (lumbar area), brisket (near xyphoid), medial side of hindquarter (proximal knee joint), medial side of forequarter (proximal elbow joint), as well as the skinned head (masseter). The results can be summarized as follows: Spray washing leads to bacterial contamination of the dorsal area of sheep, i.e., a portion of the carcass less likely soiled by the slaughter personnel. According to our experimental design, spray washing does not reduce nor increase bacterial contamination of the ventral area of sheep, i.e., a portion of the carcass most likely soiled by the slaughter personnel. Thus, spray washing does not improve the microbial status of sheep carcasses. As any additional water remaining on the carcass - apart from all that was stated above - enhances multiplication of bacteria in the long run, we do not regard spray washing a desirable asset in slaughter technology.