Purification of angiotensin I-converting enzyme-inhibitory peptides from the enzymatic hydrolysate of defatted canola meal

Defatted canola meals from seeds of different processing origins were hydrolyzed by Alcalase to give hydrolysates that inhibited angiotensin converting enzyme (ACE) activity. Heat treated meals yielded protein hydrolysates with 50% ACE-inhibitory concentrations of 27.1 and 28.6 μg protein/ml compared with 35.7 and 44.3 μg protein/ml for the none-heat treated meals. Separation of the hydrolysate on a Sephadex G-15 gel permeation column (GPC) yielded a fraction with an IC50 value of 2.3 μg protein/ml. Amino acid analysis showed that the GPC fraction contained 45% content of aromatic amino acids in comparison to 8.5% of the hydrolysate. Two peptides, Val-Ser-Val (IC50 = 0.15 μM) and Phe-Leu (IC50 = 1.33 μM) were purified, and located in the primary structure of canola napin and cruciferin native proteins. The results suggest that canola protein hydrolysate is a potential ingredient for the formulation of hypotensive functional foods.