The oligopeptides of sweet and acid cheese whey

The 12% TCA-soluble oligopeptide fraction of sweet whey from Provolone and Grana Padano cheese, and of acid whey from Quarg cheese was fractionated by HPLC and the peptide components identified using a combination of mass spectrometry and Edman degradation. In the sweet whey, in addition to the two differently phosphorylated forms of caseinomacropeptide (CMP), the peptides β-CN(1-29), β-CN(1-28), αs1-CN(f1-22), and αs1-CN(f1-23) were found. The chymosin-derived αs1-CN peptides were absent from the Quarg cheese whey, whereas shortened forms occurred as a consequence of the degradation by starter proteinases. In Quarg cheese whey, 50 peptides were from β-CN, 34 from κ-CN, seven from αs1-CN and none from αs2-CN. Some peptides known to be released during the in vitro action of PI-and PIII-type proteinases on single casein fractions occurred also in Quarg cheese whey.