Identification of Low Molecular Weight Peptides in Gouda-type Cheese and Evidence for the Formation of These Peptides from 23 N-terminal Residues of αsl-casein by Proteinases of Streptococcus cremoris H61

ABSTRACT Water‐soluble extracts from Gouda‐type cheese in a 0.05M sodium citrate buffer at pH 4.0 were fractionated by high‐pressure liquid chromatography (HPLC) before and after ripening for 1, 2, and 3 months. Three major peptides were isolated from each sample of extract, but size of the peaks increased with ripening period. The amino acid compositions of these peptides were similar to fragments of αsl‐casein, i.e., αsl‐CN(fl‐9), αsl‐CN(fl‐13) and αsl‐CN(fl‐14). αsl‐CN(fl‐23) was hydrolyzed by cellular proteases of Streptococcus cremoris H61; seven main peptides including αsl‐CN(fl‐9), αsl‐CN(fl‐13) and αsl‐CN(fl‐14) were isolated and characterized by HPLC. This suggests that hydrolysis of αsl‐CN(fl‐23) by lactic acid bacterial proteinase is one of the main pathways of αsl‐casein degradation during Gouda‐type cheese ripening.