Abstract
Wheat gluten was hydrolyzed by six proteases, pepsin, rapidase, actinase, bromelain, bioprase and papain. Peptide fractions possessing molecular weight between 500 and 10, 000 (MW 500-10, 000) were prepared from their gluten hydrolyzates with ultrafiltration. Peptide fractions (MW 500-10, 000) from gluten hydrolyzate by five proteases except for actinase elicited strong bitterness, while one by actinase elicited slight bitterness and umami. Deamidation of the latter peptide fraction in 0.5 N HCl at 120°C for 15 min further decreased its bitterness and increased its umami. This deamidated peptide fraction was separated into two fractions with MW 500-1, 000 and MW 1, 000-10, 000. The addition of the former to the niboshi soup stock have shown to enhance its umami.
