The Antioxidative Characteristics of Taro and Sweet Potato Protein Hydrolysates and Their Inhibitory Capability on Angiotensin Converting Enzyme

Proteins from taro (Colocasia esculenta (L.) Schott, Betelnut) and sweet potato (Ipomoea batatas (L.) Lam, Tainong No. 57) were hydrolyzed with pepsin and the antioxidative capacities of hydrolysates were analyzed. Hydrolysates of taro or sweet potato were further fractionated into different molecular weight fractions, namely >10 kDa, 5-10 kDa, 1-5 kDa, <1 kDa, and the antioxidative capacity and angiotensin converting enzyme (ACE) inhibitory ability of these fractions were determined. Results indicated peptic hydrolysates from taro and sweet potato proteins exhibited antioxidative capacity and ACE inhibition. High ACE inhibition was found for taro hydrolysate with molecular weight fraction of 1-5 kDa with an IC50 of 0.2571 mg/mL. Antioxidative capacity of molecular weight fraction of taro decreased with decreasing molecular weight. Molecular weight fraction of > 10 kDa from sweet potato was found to have better antioxidative capacity. Regardless species, molecular weight fraction with >10 kDa had the highest antioxidative capacities.