Identification of large phosphopeptides from β-casein that characteristically accumulate during ripening of the semi-hard cheese Herrgard

The peptide composition of a cheese reflects its characteristic ripening process, and in this study, large hydrophobic phosphopeptides that accumulate in semi-hard cheese, Herrgard, were identified. Anion exchange chromatography, reverse phase (RP) HPLC, liquid chromatography mass spectrometry and N-terminal amino acid sequencing were used. Milk from homozygotic cows was used to prepare beta-casein A1 and A2, and peptides produced from their hydrolysis by plasmin were analysed to support identification of the peptides in cheese. Eight large phosphopeptides released by plasmin hydrolysis of beta-casein were identified in the semi-hard cheese, i.e., fractions (f29-105, f29-107, f1-105, f1-107) A1 and A2. Four other peptides that accumulated in the cheese, co-eluted on RP-HPLC with the large primary plasmin-derived phosphopeptides and contributed significantly to two characteristic large peaks, i.e., one peak for each of the two genetic variants A1 and A2 of two beta-casein fractions, mainly (f29-93) but also (f30-93). (c) 2006 Elsevier Ltd. All rights reserved.