Identification of caseinophosphopeptides generated through in vitro gastro-intestinal digestion of Beaufort cheese

Abstract

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.