Concentration Dependent Effect of Enzymatic Fish Protein Hydrolysate on the State of Water and Denaturation of Lizard Fish (Saurida wanieso) Myofibrils during Dehydration

Abstract

To utilize fishery waste products as functional food material, the fish protein hydrolysate (FPH) was prepared from fish scraps of three marine species by protease treatment. The added-concentration dependent effects of FPH (2.5-12.5%, dry weight/wet weight) on the state of water and denaturation of lizard fish myofibrils were evaluated by desorption isotherm curves, myofibrillar Ca-ATPase activity, and unfrozen water which was determined by differential scanning calorimetry during dehydration. The water activity (A_w) in myofibrils was distinctly decreased with the increasing concentration of FPH from 2.5% up to 10.0%, although the A_w added with 12.5% of FPH was almost equal to that with 10.0% of FPH. The amount of unfrozen water in myofibrils during dehydration was increased by the addition of FPH, and the greatest increase was found at 5.0-10.0%. The FPH suppressed the inactivation of myofibrillar Ca-ATPase activity during dehydration, and a larger effect of suppression was observed at 7.5% addition of FPH. These findings suggest that peptides produced in FPH functioned to stabilize the hydrate water surrounding the myofibrils and suppressed their dehydration-induced denaturation.