Identification of peptides in commercial yogurt

摘要

To determine the presence of peptides in the fermented milk, peptides in yogurt commercially available was studied. A 70 percent ethanol-soluble fraction was prepared from the yogurt whey, and peptides contained therein were isolated and analyzed byhigh performance liquid chromatography with ODS columns, which resulted in many peaks. Thus, the primary structure of these peptides was studied based on the arnino acid composition and N-terminal sequence analyses. As a result, 24 peptides were identified which include 14 derived from beta-casein and 10 from kappa-casein. No peptides derived from alpha s1-casein was found. The beta-casein derived peptides were noted at 47-93 fractions and 166-209 fractions of its peptides chain, while the kappa-caseinderived peptides were noted at 24-65 fractions and 107 fraction to the C-terminal, two regions respectively. Among the identified peptides, none of them corresponded with any functional peptides derived from the known casein. However, some peptides hadsuch functional peptides within them. Further, the presence of bitter peptides (beta-casein-CN (192-209), (193-209)) was also noted.