Abstract
To determine the presence of peptides in the fermented milk, peptides in yogurt commercially available was studied. A 70% ethanol-soluble fraction was prepared from the yogurt whey, and peptides contained therein were isolated and analyzed by high performance liquid chromatography with ODS columns, which resulted in many peaks. Thus, the primary structure of these peptides was studied based on the amino acid composition and N-terminal sequence analyses. As a result, 24 peptides were identified which include 14 derived from β-casein and 10 from κ-casein. No peptides derived from αs1-casein was found. The β-casein derived peptides were noted at 47-93 fractions and 166-209 fractions of its peptides chain, while theκ-casein derived 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 had such functional peptides within them. Further, the presence of bitter peptides (β-casein-CN (192-209), (193-209)) was also noted.
