Characterization of hydrolysates produced by mild-acid treatment and enzymatic hydrolysis of defatted soybean flour

Acid (0.05-0.2 N HCl) pre-treatments and subsequent enzymatic hydrolysis (Alcalase (TM) and Flavourzyme (TM)) of defatted soybean hour (DSF) were performed under aseptic conditions. The acid pre-treatment Facilitated enzymatic hydrolysis of the protein in DSF by increasing the nitrogen solubility index. protein was hydrolyzed primarily during the first 5 h of enzymatic hydrolysis. The degree of hydrolysis and alpha -amino nitrogen contents of the hydrolysates increased after acid pretreatment. The average peptide chain lengths were estimated at 7 similar to8 amino acid units after 3 h hydrolyzation by Alcalase, and 3-5 amino acid units after 21 h by Flavourzyme/Alcalase mixture. Gel permeation chromatography provided molecular size distribution to determine the molecular weights of the corresponding hydrolysates. At the end of 24 h enzymatic hydrolysis, the amounts of free amino acid, dipeptide and tripeptide accounted for almost half of the proteins in the hydrolysate, while the oligopeptides constituted 40%. (C): 2001 Elsevier Science Ltd. All rights reserved.