THE ROLE OF AUTOLYSIS OF LACTIC-ACID BACTERIA IN THE RIPENING OF CHEESE

The importance of autolysis of lactic acid bacteria in cheese ripening is evident from the literature. However, the mechanisms and the conse quences still require investigation. The consequences of autolysis of mesophilic starters in Cheddar cheese are discussed and highlights fro m current physiological and genetic studies on starter autolysis are p resented. The relative merits of measuring starter autolysis in cheese by viable starter cell densities, electron microscopic observations a nd assay of cell-free cytoplasmic enzymes are discussed for cheese stu dies using different starter strains and added phage to achieve differ ent levels of auotolysis. The balance of both the intact and autolysed starter cells in young curd appear to be important in cheese ripening . The intact cells are necessary for physiological reactions such as l actose fermentation and oxygen removal and possibly for a number of fl avour reactions. In contrast, the main consequence of autolysed cells in cheese is to accelerate the peptidolytic reactions. The possible of autolysis of adventitious lactic acid bacteria during cheese ripening are discussed.