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 bacteriological conditions with three starters: Lactococcus lactis subsp. lactis IL416, Lactococcus lactis subsp. cremoris HP or Lactococcus lactis subsp. cremoris AM2 (increased lysis rate) and with or without Lactobacillus plantarum 1572 adjunct culture. We examined gross composition and bacterial cell counts, and assessed proteolysis in 28-day-old cheeses by nitrogen analysis, free amino acids determination and RP-HPLC of ethanol soluble peptides and casein fractions. Development and proteolytic activity of lactobacilli adjunct culture depended on the starter strain used in cheesemaking. In the presence 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 cheeses made with HP starter strain lactobacilli grew throughout ripening. Soluble nitrogen at pH 4.4 was higher in cheeses made with starter HP. Different values for free amino acids were noted for the three starter strains and between cheeses with and without lactobacilli, while peptide profiles varied from one starter strain to another and showed quantitative differences between cheeses with and without lactobacilli. Casein fraction profile was essentially the same for all cheeses. (C) 2001 Elsevier Science Ltd. All rights reserved.