Antioxidant and Ace Inhibitory Properties of Poultry Viscera Protein Hydrolysate and Its Peptide Fractions

Poultry viscera protein hydrolysate (PVPH) was fractionated using ultrafiltration membrane into three peptide fractions viz. Fractions I (>10 kDa), II (3–10 kDa) and III (<3 kDa) with yield of 13.4, 18.4 and 66.6%, respectively. Antioxidant activity of PVPH and its fractions was determined in terms of radical-scavenging activity (RSA), reducing power (RP), total antioxidant activity (TAA) and antioxidant activity index (AAI). PVPH exhibited excellent RSA and TAA at peptide concentration of 0.2 and 2.0 mg/mL, respectively. It also showed RP value as 0.4, and AAI as 500 after 100 min at peptide concentration of 9 and 30 mg/mL, respectively. Scavenging of 2, 2′-azinobis (3-ethyl-benzothiazoline-6 sulfonic acid) and hydroxyl radicals by Fraction III was found to be significantly higher than other fractions, while superoxide scavenging activity was independent of peptide size. Fraction I exhibited better RP, TAA and AAI. PVPH and Fraction III showed the highest angiotensin-converting enzyme (ACE) inhibitory activity (IC50 = 0.34 mg/mL). PRACTICAL APPLICATIONS Poultry viscera are an underutilized by-product of poultry processing industry. A rapid autolytic method was developed in our laboratory to prepare a hydrolysate from this tissue. In order to find the potential application of this value-added product, antioxidant and angiotensin-converting enzyme inhibitory properties of the peptide fractions of the hydrolysate were evaluated.