Effect of pasteurization and use of a native starter culture on proteolysis in a ewes' milk cheese

The effect of different manufacturing methods on the production of a ewes' milk cheese was studied. Three batches were made: raw milk without added st arter, raw milk with added starter, and pasteurized milk with added starter . The starter culture was composed of Lactococcus lactis subsp lactis biova r diacetylactis and Lactobacillus casei subsp casei. Samples were taken fro m all three cheese batches on 1, 90, and 180 days of ripening for analysis of the soluble nitrogen (SN) and non-protein nitrogen (NPN). SN and NPN lev els were the highest in the batch made from the pasteurized milk, which als o exhibited the highest level of degradation of the alpha(s) and beta-casei ns. Conversely, that batch had the lowest total free amino acid (FAA) conte nt. This parameter was the highest in the batch made from the raw milk with added starter. The cheeses made from the pasteurized milk presented the hi ghest serine and asparagine contents, but gamma-aminobutyric acid levels we re negligible. (C) 2000 Elsevier Science Ltd. All rights reserved.