Evaluation of Different Proportions of Distilled Water to Substrate on Functional Properties, Antioxidant and Nutritional Quality of Bigeye Ilisha (Ilisha Megaloptera) protein hydrolysate

Background and objectives: Production of fish protein hydrolysate is a method for converting the low-value economical underutilized fish species to value-added products. This study aimed to evaluate the different proportions of distilled water to the substrate on the functional characteristics, antioxidant and nutritional quality of fish protein hydrolysate of bigeye ilisha (Ilisha megaloptera) produced by enzymatic hydrolysis. Methods: After defatting of minced fish, the hydrolysis process was carried out using three different 4:1, 5:1 and 6:1 distilled water to substrate proportions by using alcalase enzyme in three replications. The protein hydrolysate samples were analyzed for approximate composition (soluble protein, moisture, fat and ash), functional characteristics (solubility, foam capacity, and foam stability), antioxidant properties (DPPH radical scavenging activity and reducing power) and mineral composition. Results: In this study, the ratio of distilled water to the substrate affected the protein hydrolysate properties and the highest amounts of hydrolysis degree and DPPH radical scavenging activity were observed in samples with 5:1 ratio. Fish protein hydrolysate obtained from 4:1 ratio had the highest amount of soluble protein, and no significant difference was observed in term of solubility with samples obtained by 5:1 ratio. Moreover, there were no significant differences in terms of lightness and foam capacity of samples obtained from 4:1 and 6:1 proportions. Conclusion: According to the results of the study, using a 4:1 ratio of distilled water to substrate led to the production of fish protein hydrolysates from bigeye ilisha with higher functional properties and nutritional composition.