PROTEOLYTIC ACTIVITY OF LACTOBACILLI IN A MODEL GOATS MILK CURD SYSTEM

Mesophyllic lactobacilli cultures propagated in MRS broth were inocula ted in goats' milk curd slurries and incubated at 30 degrees C for 10 d. The micro-organisms tested were Lactobacillus casei subsp. casei IF PL 731 and IFPL 99, and Lactobacillus plantarum IFPL 3. Whole cells, c ell-free extracts and cell lysates sere evaluated for acceleration of proteolysis in the curd slurries. Conversion of water-soluble nitrogen to non-protein nitrogen and amino acid nitrogen, reverse phase-HPLC p eak areas and ratio of hydrophobic to hydrophilic peptides, were all a ffected by the type of inoculum used as well as the strain under study . The results suggest that the accelerated-ripening model system devel oped, containing cell lysates, map be suitable as a good and rapid ind icator of the contribution of the strains to proteolysis during cheese ripening.