AN EVALUATION OF THE MICROBIOLOGICAL SAFETY OF REDUCED-FAT CHEDDAR-LIKE CHEESE

This study was carried out to investigate microbiological safety of reduced-fat Cheddar cheese. This was done by studying the behavior of two strains of Listeria monocytogenes, (Scott A-4b and V7-1a) and two species of the genus Salmonella, (Salmonella typhimurium and Salmonella senftenberg) during manufacture and aging of reduced or low-fat stirred curd Cheddar cheese made from milk containing 1.5 to 2.0% fat. The fat content of reduced-fat cheeses was between 20.03 and 21.13% while that of control cheeses was between 28.11 and 30.41%. Listeriae declined slowly in both cheeses and their rate of decline was not affected by fat reduction. During the 20-week aging period, the average (3 trials) log(10) colony forming units (CFU)/g decline in Listeria population was 0.84 in control cheese and 0.62 in reduced-fat cheese. During the same period, the average log(10) CFU/g decline in Salmonella population was 4.81 in control cheese and 5.16 in reduced-fat cheese. Salmonellae were affected by fat reduction, and during the entire aging period their population was lower in reduced-fat cheese than in control cheese. Thus, reduction of fat in the dry matter of cheese from 48 to 36% had no effect on listeriae but salmonellae declined faster in reduced-fat stirred curd Cheddar cheese.