Preparation of angiotensin I converting enzyme inhibitor from corn gluten

Hydrolysates were prepared from corn gluten containing powerful angiotensin I converting enzyme (ACE) inhibitory activity with low bitterness. Among six commercial proteases, Flavourzyme showed the highest ACE inhibitory activity (IC₅₀: 0.18 mg solid). Flavourzyme (complex type), Pescalase (endo-type), and Protease A (exo-type) were used to evaluate corn gluten hydrolysates according to the enzyme specificity. ACE inhibitory activities of the hydrolysates had the same trend as protein content. Flavourzyme and Pescalase showed high ACE inhibitory activity (IC₅₀: 0.18 mg solid and IC₅₀: 0.17 mg solid, respectively) after 8 and 1 h of hydrolysis, respectively. However, Protease A showed no changes of ACE inhibitory activity after 1 h of hydrolysis. A mixture of Pescalase and Protease A (1:1, w/w) was applied to the preparation of corn gluten hydrolysate. The hydrolysis time using the enzyme mixture was reduced from 8 to 4 h compared with Flavourzyme. Surface hydrophobicity of the hydrolysate with the enzyme mixture was lower than that of the hydrolysate with Flavourzyme, but there was no significant difference at P < 0.05. Average hydrophobicity (Q value) of the hydrolysates with the Flavourzyme and the enzyme mixture was to be less than 1400 kcal/mol. It was assumed that there was no difference in bitterness between the hydrolysate with Flavourzyme and that with the enzyme mixture.