Squilla protein hydrolysate: In-vitro antioxidant properties and evaluation of antioxidant activity in fish nuggets

Abstract

Protein hydrolysates were prepared from squilla using five proteases namely alcalase, neutrase, flavourzyme, papain and papsin. Yield of hydrolysates ranged from 4.46 to 6.53% and protein content ranged from 69.69 plus or minus 1.00 to 82.80 plus or minus 3.93 per cent. Highest protein content was found in hydrolysate made using pepsin. At the optimum condition, DH per cent was found to be 17.75, 12.13, 17.63, 26.19 and 13.03 per cent for alcalase, neutrase, flavourzyme, papain and pepsin, respectively. DPPH free radical-scavenging assay, reducing power assay and ABTS. Scavenging activity were used to evaluate the antioxidant properties of hydrolysates from squilla. Study revealed that hydrolysate produced using alcalsae had significantly higher antioxidant properties. Hydrolysates produced using alcalase was found to have higher scavenging ability (75.46 plus or minus 0.012 per cent.) followed by pepsin, papain, neutrase and flavourzyme. Hydrolysate produced using different type of protease from squilla exhibited strong ABTS scavenging capacities. Evaluation of in-vivo antioxidant activity of squilla protein hydrolysate was conducted in fish nuggets under refrigerated storage. Fish nuggets with 1 per cent squilla protein hydrolysate made from alcalase and flavourzyme showed significantly lower PV and TBARS values as compared to control sample at the end of 10 days of storage. Sensory scores for appearance, colour, flavor, odour, taste and texture were found to be higher for the fish nuggets containing hydrolysate. The results of the study indicate that squilla protein hydrolysate is a promising alternative to replace harmful synthetic antioxidants in fishery products.