Role of starter enzymes during ripening of cheddar cheese made from pasteurized milk under controlled microbiological conditions

Proteolysis and flavour development in Cheddar cheeses made without starter or with a proteinase-positive (prt(+)) or a proteinase-negative (prt(-)) strain of Lactococcus lactis ssp. cremoris were monitored during ripening. The results showed that the coagulant and plasmin were mainly responsible for the degradation of caseins while small peptides and free amino acids (FAA) were produced mainly by starter enzymes. Although starter peptidases were capable of producing some small peptides and FAA in the cheese made with the proteinase-negative starter, proteinase activity resulted in increased levels of small peptides and amino acids in the cheese made with the proteinase-positive starter. The flavour intensity and flavour acceptability of the chemically-acidified cheeses were poor. The cheeses made with the prt(+) starter received the highest scores for flavour intensity and flavour acceptability. (C) 1997 Elsevier Science Limited.