To add more useful characteristics to a hydrolyzed peptide obtained by hydrolyzing a protein derived from a natural product such as an animal, a plant or a microorganism or its derivative without deteriorating the characteristics possessed thereby.
A hydrolyzed peptide obtained by hydrolyzing a protein derived from a natural product such as an animal, a plant or a microorganism or its derivative is reacted with N,N'-dicarboxy cysteine anhydride in the presence of an alkali and decarboxylation is then carried out with an acid to provide a peptide containing the cysteine introduced thereinto. The disulfide bond thereof is further reduced to afford the hydrolyzed peptide containing the cysteine introduced thereinto or its derivative. Thereby, the peptide, containing the cysteine introduced thereinto and having added characteristics, possessed by the cysteine in addition to the characteristics possessed by the hydrolyzed peptide or its derivative or further enhanced characteristics based on the cysteine is produced.
SHINTANI HIROSHI
MATSUKAWA YOSHIE
