Lactococcal Lysis and Curd Proteolysis: Two Predictable Events Important for the Development of Cheese Flavour

We have previously estimated the lytic ability of many lactococcal strains as well as their proteinase and global peptidase activities using buffer and pseudo-curd tests. In the present study, we have selected five lactococcal starters having different lytic and proteolytic properties to manufacture semi-hard cheeses. The lytic behaviour of the five strains in cheese correlated with their estimated lytic ability. Cell lysis positively influenced the ripening of cheese: proteolysis was more advanced in cheeses made with the three lytic strains. However, high cell lysis was not sufficient to obtain cheeses with good flavour scores and in particular non-bitter cheeses. The cheeses made with the strain Lactococcus lactis subsp. cremoris RD251, whose cells lysed highly during ripening but whose global peptidase potential was low, were bitter as were the cheeses made with the low lytic strain Lactococcus lactis subsp. lactis RD232 whose cells possessed a high proteolytic potential.