Microbial quality of lamb carcasses during processing and the acridine orange direct count technique (a modified DEFT) for rapid enumeration of total viable counts

This study was designed to set up a hazard analysis and critical control points (HACCP) system for sheep slaughtering operations at four different plants in Ireland and to determine the differences plants in terms of microbial contamination. A single carcass area, the abdomen, was examined by swabbing and a microbiological profile was determined at different stages along the slaughter line. The level of contamination was assessed from the total bacteria counts, Enterobacteriaceae and Listeria spp. For the total counts, a modified direct epifluorescent filter technique (acridine orange direct count technique (AODC)) was developed and tested. No significant differences were found among plants in the level of bacterial contamination. This was observed for all groups of organisms. The rapid direct technique (AODC) was found to be very successful. A correlation coefficient of 0.87 was obtained for this method and the standard plate count. Each test could be carried out in about 10–15 min and could be used to predict the standard plate count.