Valorisation of tuna viscera by endogenous enzymatic treatment

Abstract

Fish processing industry generates a considerable amount of by-products which represent an environmental problem. Only a small portion of these residues is used for the production of low marketable products. Therefore, industrially scalable processes yielding value-added products would be highly desirable. Different to others studies, this work deals with potential valorisation of bullet tuna (Auxis rochei) viscera using its endogenous enzymes without previous separation stage for the production of bioactive hydrolysates. Functional and bioactive properties of hydrolysates produced at different degree of hydrolysis (DH 3%, 6% and 9%) were evaluated. The endogenous enzyme hydrolysates (EH) obtained by the proposed low cost treatment were compared with hydrolysates produced with a well-known commercial enzyme: subtilisin. Regarding functional properties, EH presented similar or even better solubility, emulsifying and oil binding capacities than subtilisin hydrolysate (SH). EH also showed very interesting antioxidative properties, particularly metal reducing and radical scavenging activity. Additionally, the ACE inhibitory activity of EH at low degree of hydrolysis was comparable to SH. According to these results, bullet tuna viscera protein can be value-added by endogenous enzyme hydrolysis.