Characterization of Fish Protein Hydrolysate from Red Meat of <em>Euthynnus affinis</em> and its Application as an Antioxidant in Iced Sardine

Abstract

Effective utilization of the fishery waste to produce value-added products has emerged as a priority area for the global seafood industry development. Tuna (<em>Euthynnus affinis</em>) red meat proteins which are generally discarded as waste in canning industry was hydrolysed using papain enzyme (0.5% w/w), and applied as antioxidant in dressed sardine during ice storage. Tuna protein hydrolysate (TPH) comprised of about 89.9 ± 0.6% protein, 1.35 ± 0.15% moisture, 2.71 ± 0.06% fat and 4.03 ± 0.02% ash. A proportional increase in the degree of hydrolysis of tuna protein with time was observed from 14.96% at 15 minutes reaching 22.98% at 45 minutes of hydrolysis. DPPH scavenging activity and reducing power improved with hydrolysis and was found to be 56.82 ± 0.74 % for 2 mg/ml protein and 0.614 ± 0.009 for 10 mg/ml protein, respectively at 45 minutes of hydrolysis. Sardine samples got darkened with storage period as indicated by decreased L* values. Similarly a reduction in hardness value was observed in ice stored sardine samples, more prominent in control compared to treated samples. TBA studies indicated that dip treatment in 0.5% TPH solution significantly reduced (p < 0.05) the oxidation in ice stored dressed sardine compared to control revealing the application of protein hydrolysate as a natural antioxidant in foods.