Antioxidant properties of hydrolyzate produced from the crude extract of <em>Hilsa kelee</em>

Abstract

Hilsa kelee also known as "Karattaya" is a seasonal fish mainly found in tropical coastal waters and used for fish feed production due to its low market value. Therefore, this study was designed to determine the functional properties of fish protein hydrolyzate (FPH) produced from the crude extract of Hilsa kelee. For extraction, 20 mg/mL concentrated water-soluble and salt-soluble crude extracts were mixed with protease, papain, α-chymotrypsin, and elastase in 1:100 (enzyme: substrate) ratios. Each sample was incubated at different time intervals (0, 3, 6, 9, 12, and 24 hours) under predetermined optimum pH and temperatures. SDS-PAGE, TBARS, and DPPH assays and ferrous chelation activity were measured in the selected best hydrolysates. According to SDS-PAGE analysis for water and salt extracted, the following hydrolysis time lags were selected, protease (3 h), α-chymotrypsin (6 h), Elastase (6 h) and papain (6 h for water and 3 h for salt extraction). In the TBARS assay, the FPHs from salt soluble proteins with papain showed the highest antioxidant properties (5.84±0.05 MDA mg/L) compared to other treatments (p<0.05). The DPPH assay showed the highest radical scavenging activity with salt soluble proteins hydrolyzed with α-chymotrypsin (p<0.05). Analysis of ferrous chelation activity showed that FPHs produced from water-soluble proteins with α-chymotrypsin (20.81±0.02%) had the highest chelation (p<0.05). This concludes, FPHs produced from Hilsa kelee using papain and α-chymotrypsin enzymes contain antioxidant properties, and iron-binding activity.