Characterization, ACE Inhibitory and Antioxidative Properties of Peptide Fractions Obtained from White Shrimp (Litopenaeus vannamei)

Background: Aquatic organisms are considered to be an important source of bioactive peptides with a high antioxidant and antihypertensive capacity. Therefore, the objective of this study was to hydrolyse peptide fractions from white shrimp (Litopenaeus vannamei) muscle by Alcalase and Protamex and to evaluate the angiotensin I-converting enzyme (ACE) inhibitory and the antioxidant activities. Methods: Protein hydrolysates of White shrimp were obtained by enzymatic hydrolysis using Alcalase and Protamex until the degree of hydrolysis reached 10% and 20%. Peptide fractions were obtained from White shrimp protein hydrolysates by ultrafiltration using membranes with sizes of 10 and 3 kDa. The antioxidant activity was evaluated for the three peptide fractions (F1: >10 kDa, F2: 3-10 kDa and F3: <3 kDa). To measure the antihypertensive activity, fractions with molecular sizes of less than 3 kDa were used. Results: The fractions obtained with Alcalase showed greater inhibitory effects on the ACE. In general, the molecular weight of the fractions influenced the antioxidant activity, with fractions smaller than 3 kDa having a high capacity for sequestering the DPPH radical, while peptide fractions with a size greater than 10 kDa presented higher reducing power. However, in capturing the ABTS radical, a high antioxidant capacity was observed for both fractions. Conclusion: The results suggest white shrimp would be an attractive raw material for the manufacture of antioxidant and anti-hypertensive nutraceutical ingredients.