Hydrolysis of beta-casein (193-209) fragment by whole cells and fractions of Lactobacillus casei and Lactococcus lactis

Whole cells and fractions of Lactococcus lactis subsp. lactis IFPL 359 and Lactobacillus casei subsp. casei IFPL731 were studied. Hydrolysis products were separated by reversed-phase, high-performance liquid chromatography (R P-HPLC). Under conditions, pH 5.2 and 3% NaCl, L. casei IFPL 731 was more a ctive in hydrolysis of the beta-casein (f193-209) peptide than was L. lacti s IFPL 359. This hydrolyzing activity was attributed for L. casei IFPL 731 by the cell-wall proteinase. Hydrolysis of the peptide by the intracellular extract of L. casei IFPL731 was mainly located in the fraction that contai ned endopeptidase and Pep N aminopeptidase activities. Results may help pro vide approaches and treatments to control bitterness in cheese products.