Evaluation of the Bacteriological Health Risk of 60-Day Aged Raw Milk Cheddar Cheese

One hundred twenty-seven 60-d aged Cheddar cheese samples produced by 21 provincially inspected cheese plants were analyzed by 8 regional laboratories of the Ontario Ministry of Health. Coliforms were detected in 37 (31.2%) and fecal coliforms confirmed in 22 (18.3%) samples, with geometric mean counts per g of 92.5 and 79.3, respectively. Staphylococcus aureus was found in only two products at a level of >1000 per g. Salmonella spp. and Campylobacter jejuni were not isolated from any of the samples tested. Yersinia enterocolitica was isolated from one product; however, the isolate was bile esculin-and salicin-positive, and considered a non-pathogenic biotype. The pH of these aged Cheddars ranged between 4.98 and 5.50, with a mean of 5.26. Alkaline phosphatase activity was detected in 94 (79.7%) of the 118 samples tested. These results suggest that 60-d aged raw milk Cheddar cheese produced in Ontario does not pose a significant bacteriological health risk.