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

Abstract

The effect of different manufacturing methods on the production of a ewes’ milk cheese was studied. Three batches were made: raw milk without added starter, raw milk with added starter, and pasteurized milk with added starter. The starter culture was composed of Lactococcus lactis subsp lactis biovar diacetylactis and Lactobacillus casei subsp casei. Samples were taken from 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 levels were the highest in the batch made from the pasteurized milk, which also exhibited the highest level of degradation of the α s and β-caseins. Conversely, that batch had the lowest total free amino acid (FAA) content. 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 highest serine and asparagine contents, but γ-aminobutyric acid levels were negligible.