Functional properties of protein hydrolysates from different body parts of horse mackerel (Magalaspis cordyla) and croaker (Otolithes ruber)

Protein hydrolysates are economically important value added products in the food industry. Hydrolysis of fish proteins is practiced for the improvement of nutritional characteristics, retarding deterioration, removal of toxic or inhibitory ingredients and modification of functional properties. Four different body parts viz., skin, muscle, bone and viscera of horse mackerel (Magalaspis cordyla) and croaker (Otolithes ruber) were hydrolyzed, through in vitro gastrointestinal digestion procedure using commercial proteases (pepsin, trypsin and a-chymotrypsin). The obtained protein hydrolysates were lyophilized and characterized for functional properties like solubility, emulsifying activity index (EAI) and foaming ability at different pH ranging from 2 to 10. After 6 h hydrolysis, all the hydrolysates showed 70% (p < 0.05) protein solubility at different pH evaluated. Lower emulsifying and foaming capacity (p < 0.05) was noticed at pH 4 and a gradual increase in these properties observed with the increasing pH. Current results revealed that these hydrolysates from various body parts of horse mackerel showed good functional properties in wide range of pH and protein hydrolysate obtained from viscera has showed high functional properties than remaining body parts. These results suggest that horse mackerel and croaker protein hydrolysates could find potential applications as functional food ingredients as emulsifiers and foaming agents.