Proteolysis and volatile components of reduced-fat cheeses made from ultrafiltered milk and different starters supplemented with lactobacilli and Lac-Prt- lactococci

Abstract

Proteolysis and volatile components of semi-hard cheeses manufactured from a mixture of cow's, ewe's and goat's milk, with reduced fat content and concentrated by ultrafiltration, were followed during ripening. A starter culture (IFPL), consisting of several strains of Lactococcus, Lactobacillus and Leuconostoc, selected previously for its high proteolytic activity, and the same starter with the addition of a concentrate of Lactococcus lactis subsp lactis T1, lacking the ability to utilize lactose and casein (Lac- Prt-), were tested with the aim of accelerating cheese ripening as compared with a commercial starter (FD). Casein hydrolysis was not affected by the type of starter culture employed, whereas appreciable differences were found in the non-volatile water-soluble nitrogen fraction. The peptide pattern allowed a clear distinction among cheeses made with different bacterial cultures. IFPL cheeses exhibited, after 1 month of ripening, a higher content of total free amino acids than FD cheeses after 3 months of ripening. Furthermore, the addition of L lactis T1 to the IFPL culture noticeably increased the release of total free amino acids during ripening, as well as the content of total volatile compounds.