Bioactivity Evaluation of Peptide Fractions from Bighead Carp (Hypophthalmichthys nobilis) Using Alcalase and Hydrolytic Enzymes Extracted from Oncorhynchus mykiss and Their Potential to Develop the Edible Coats

Marine by-products contain valuable protein components that can be extracted and analyzed to determine their quality, composition, and performance. In the present study, Bighead carp (Hypophthalmichthys nobilis) heads were hydrolyzed by Alcalase and extracted alkaline protease from rainbow trout (Oncorhynchus mykiss) viscera and fractionated by membrane ultrafiltration into four molecular size fractions (< 3, 3-10, 10-30, 30 < kDa). Amino acid composition, foaming, emulsifying, and solubility properties of the fractions were characterized. Also, the antioxidant and antibacterial activity of the obtained fractions was assessed via ABTS, DPPH, metal chelating, and disc diffusion methods. Fractions of < 3 kDa showed the best activity in the antioxidant and antibacterial tests, so these fractions were used to develop the edible coats. Edible coatings based on these fractions and developed coats incorporating them into the alginate and starch solution coat were used to preserve rainbow trout fillets during cold storage. Based on obtained results, developed starch or alginate coatings enriched with 3 kDa fractions reduced 2-thiobarbituric acid (TBA), peroxide value (PV), total volatile basic nitrogen (TVB-N), and bacterial growth (TVC and PTC) more effectively than control treatments. According to the findings, these peptide fractions could be used in the development of active packaging as antimicrobial and antioxidant components.

Automated summary

Marine by-products, specifically protein components from Bighead carp heads and alkaline protease from rainbow trout viscera, were extracted and analyzed in this study. These components were fractionated by membrane ultrafiltration and characterized by their amino acid composition, foaming, emulsifying, and solubility properties. The antioxidant and antibacterial activity of the fractions were also evaluated. The < 3 kDa fractions exhibited the best activity and were used to develop edible coatings for preserving rainbow trout fillets, which effectively reduced oxidative and microbial deterioration.