Antioxidant activities of peptide fractions derived from freshwater mussel protein using ultrasound-assisted enzymatic hydrolysis

Abstract

The freshwater mussel protein was hydrolysed using ultrasound-assisted enzymolysis. Ultrasound-assisted freshwater mussel protein hydrolysates (UPH) were divided into four fractions (> 10, 6–10, 3–6, and < 3 kDa) using ultrafiltration, and the fraction with the highest antioxidant activity was further subdivided into four fractions (F<sub>1</sub>–F<sub>4</sub>) using gel chromatography. The amino acid compositions and antioxidant activities (DPPH, hydroxyl and superoxide radical scavenging activities, reducing power, ferrous ion chelating activity, and inhibition of linoleic acid oxidation) of peptide fractions were investigated. The results showed that the antioxidant activity of the < 3 kDa fraction was significantly higher than that of UPH, > 10, 6–10, and 3–6 kDa fractions. The antioxidant activity of F<sub>2</sub> was again higher compared with the < 3 kDa fraction and higher than that of F<sub>1</sub>, F<sub>3</sub>, and F<sub>4</sub>. Amino acid analysis showed that the antioxidant activities (except for chelating activity) of peptides increased with increasing hydrophobic amino acid content. The < 3 kDa and F<sub>2</sub> fractions exhibited strong inhibition of linoleic acid oxidation, their effects being even better than that of ascorbic acid (Vc) and l-glutathione (GSH). Therefore, these peptide fractions from freshwater mussel may be a potential natural antioxidant that could be added to various foods.