THE EFFECTS OF FREEZING AND FROZEN STORAGE OF EWES MILK CHEESE ON THEVIABILITY AND PROTEOLYTIC ACTIVITY OF LACTOCOCCI USED AS A STARTER

A study has been conducted on the effect of two freezing conditions (s low and fast) and frozen storage of ewe's milk cheese (-20 degrees C f or 4 months) on the viability and the proteolytic (caseinolytic and am inopeptidase) activity of Lactococcus lactis subsp. lactis and L. lact is subsp. cremoris used as starters in the manufacture of cheese. The study was carried out on the lactococci subjected to freezing and froz en storage, either in the cheeses or in curds simulating a model syste m. As well as other parameters used to quantity microbial activity, th e total viable Counts during the subsequent cheese ripening have been analysed in the frozen cheeses. Frozen storage of the investigated lac tococci, either in the cheese or in model systems, gave rise to signif icant decreases in the caseinolytic and aminopeptidase activities grea ter than did freezing alone. No clear differences were found in enzyma tic activity values when using slow or fast freezing conditions. Stora ge of the cheeses under frozen conditions also affected microbial viab ility and consequently caused a greater decrease of the viable flora d uring subsequent ripening of the frozen stored cheeses.