Abstract: Wheat protein was hydrolyzed respectively with pepsin, acid proteinase, papain, trypsin. The results showed that the effect of pepsin is the best. The effects of the substrate concentration (S), enzyme concentration (E), reaction temperature (T), reaction time (t) and pH value on the degree of hydrolysis (DH) and polypeptides yields were studied by single factor tests. The optimal conditions are determined by orthogonal tests as follows: substrate concentration10%, enzyme-substrate ration (E/S) 7%, temperature (T) 35 ℃, time 3 h and pH 2.0. Under the above conditions, the DH and polypeptides yield are 4.62% and 50.64% respectively. The molecular weights of hydrolysates from wheat protein were determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). All the molecular weights are below 7.0 kD and the most products are of molecular weight between 4.1 kD and 1.4 kD, which indicates that the hydrolysates from wheat protein are polypeptides.

Key words: wheat protein, enzymatic hydrolysis, active polypeptide, SDS-polyacrylamide gel electrophoresis (SDS-PAGE)