Proteolysis during ripening of miniature washed-curd cheeses manufactured with different strains of starter bacteria and a Lactobacillus plantarum adjunct culture

Washed-curd miniature cheeses were manufactured under controlled bacteriolo gical conditions with three starters: Lactococcus lactis subsp. lactis IL41 6, Lactococcus lactis subsp. cremoris HP or Lactococcus lactis subsp. cremo ris AM2 (increased lysis rate) and with or without Lactobacillus plantarum 1572 adjunct culture. We examined gross composition and bacterial cell coun ts, and assessed proteolysis in 28-day-old cheeses by nitrogen analysis, fr ee amino acids determination and RP-HPLC of ethanol soluble peptides and ca sein fractions. Development and proteolytic activity of lactobacilli adjunc t culture depended on the starter strain used in cheesemaking. In the prese nce of IL416 and AM2 lactobacilli cell counts reached similar to 10(7) CFU g(-1) the first day of ripening and remained almost constant, while in chee ses made with HP starter strain lactobacilli grew throughout ripening. Solu ble nitrogen at pH 4.4 was higher in cheeses made with starter HP. Differen t values for free amino acids were noted for the three starter strains and between cheeses with and without lactobacilli, while peptide profiles varie d from one starter strain to another and showed quantitative differences be tween cheeses with and without lactobacilli. Casein fraction profile was es sentially the same for all cheeses. (C) 2001 Elsevier Science Ltd. All righ ts reserved.