Soybean protein was hydrolyzed by enzymes derived from Aspergillus oryzae or Rhizopus niveus, and general characteristics of these hydrolyzates were compared.
1. The emulsifying strength of hydrolyzates by Asp. enzyme was lower than that of unhydrolyzed protein, whereas that of hydrolyzates by Rhi. enzyme was similar or rather higher than that of unhydrolyzed protein.
2. Nitrogen solubility indexes of hydrolyzates reached at most 70 and 75 by Asp. enzyme at 30°C and 40°C, respectively, and 58 and 60 by Rhi. enzyme, respectively, at the same reaction temperature. These indexes could not be increased any more even though, the amount of each enzyme was in creased. Furthermore, a bitter taste appeared in both hydrolyzates, when NSI exceeded 50.
3. The degree of hydrolysis of soybean protein was assumed to be closely related to emulsifying strength, judging from the average peptide length and SDS-polyacrylamide gel electrophoresis pattern.
4. Subunits from 11 S protein were decomposed almost entirely by adding 1g Asp. enzyme/100 g substrate.
5. Phenylalanine, leucine, arginine and lysine were liberated in this order of quantity in Asp. hydrolyzates, and phenylalanine, arginine and leucine in Rhi. hydrolyzates. These amino acids are of bitter taste.
