Preparation of Skipjack Tuna (Katsuwonus pelamis) Protein Hydrolysate Using Combined Controlled Enzymatic Hydrolysis and Glycation for Improved Solubility and Emulsifying Properties

Abstract

Preparation of the hydrolysate from under-utilized skipjack tuna (Katsuwonus pelamis) protein with improved functional properties using combined controlled enzymatic hydrolysis and glycation was investigated. Five enzymes including alcalase, flavorase, neutrase, trypsin and protamex were performed to hydrolysis under the optimum conditions. The results showed that 5-hour hydrolysis led to increases in degree of hydrolysis (DH) and amino acids content, and change in soluble protein content. To obtain considerable small-size peptides, a controlled enzymatic hydrolysis (2.5 h) by trypsin was carried out. This condition produced nearly 80% soluble protein which could not be precipitated by 10% TCA. The resulting hydrolysate was then subjected to glycation with alginate at 60 °C and 65% relative humidity for 3 hours. Functional properties assay showed that glycation significantly increased (P<0.05) the solubility, emulsifying activity index (EAI) and emulsion stability index (ESI). This work suggested that the controlled enzymatic hydrolysis in combination with glycation would effectively improve the functional properties of fish protein hydrolysates.