CHANGES IN THE CONTENT OF LACTOSE AND FREE AMINO ACIDS DURING THE RIPENING OF SALTED CHEESE

This study examined the changes in lactose content and free amino acid (FAA) levels during the ripening of cow’s milk cheese treated with 20% brine (14–16 °C, 24 h). Two cheese variants were prepared from pasteurised cow’s milk (3.8% fat): one coagulated with chymosin only (DLK) and one with chymosin supplemented with a microbial starter culture (DLK-S). Cheese samples were stored at 14–15 °C and analysed on days 12, 22 and 32 of ripening for moisture, pH, titratable acidity, sodium chloride, lactose and free amino acids. In the chymosin-only variant (DLK), the lactose content decreased gradually on days 12, 22 and 32. The FAA content remained low and essentially unchanged indicating that lactic acid bacteria originating from the milk alone exerted limited lactose-metabolising and proteolytic activity during the 32-day ripening period. By contrast, the starter-supplemented variant (DLKS) showed a marked acceleration in both processes: lactose declined on day 12 and fell below the detection limit by day 32, while FAA levels increased steadily. A positive correlation between lactic acid production and lactose consumption was observed in both variants. These results confirm that the addition of a microbial starter culture to brine-salted cheese markedly enhances lactose catabolism and proteolysis during ripening. While the indigenous lactic acid bacteria in DLK maintained only a basal level of metabolic activity, the defined starter in DLK-S drove lactose to exhaustion by day 32 and produced FAA levels approximately five times higher than those in the chymosin-only cheese. The findings highlight the essential role of starter cultures in the development of flavour and aroma compounds in salted cheese during extended ripening.