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Caseinophosphopeptides (CPPs) are bioactive peptides originating from proteolysis of caseins, the main proteins of milk. In this study, the generation of CCPs during Beaufort cheese making and by in vitro simulated gastro-intestinal hydrolysis using pepsin and pancreatin were assessed using selective precipitation and liquid chromatography–electrospray ionisation tandem mass spectrometry. Seventy-two water-soluble CPPs, mainly originating from β-casein, were identified in Beaufort cheese, while 79 CPPs, mainly generated from α s1 -caseins, were obtained from enzymatic hydrolysates. Most of the peptides generated by the action of digestive enzymes were monophosphorylated; however, 17 out of the 23 polyphosphorylated CPPs identified from digested Beaufort cheese still contained the characteristic cluster sequence Ser(P)-Ser(P)-Ser(P)-Glu-Glu, providing calcium-binding properties to CPPs. The content of CPPs in Beaufort cheese before and after the action of digestive enzymes was estimated to be 230 and 275 mg per 100 g of fresh cheese, respectively. The action of proteolytic digestive enzymes on CPPs is discussed.

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.