Isolation and Identification of Low Molecular Weight Peptides in Gouda Cheese

Abstract

70%-Ethanol soluble extracts in Gouda cheese (cheese before ripening and cheese ripened for 1 and 4 months) were prepared to examine low molecular weight peptides in the cheese. The extracts were fractionated by high pressure liquid chromatography (HPLC) fitted with ODS column and UV detection. As the ripening period progressed, the number and quantity of peptide peaks extracted increased. The amino acid sequence of the main peaks isolated from cheese ripened for 4 months were determined as follows; Tyr, Phe, Trp, αs1-CN(f1-7), (f1-9), (f1-13), (f1-14), (f1-16), (f1-17) and β-CN (f47-52). With the exception of β-CN (f47-52) and amino acid; these peptides were fragments contained in αs1-CN (f1-23) produced specifically by the action of chymosin. Therefore, it was considered that these N-terminal peptides of αs1-CN identified in the cheese, were produced from 23N-terminal residues of αs1-CN on the action of proteolytic enzyme from Lactic acid bacteria which existed in the cheese.