ABSTRACT
With the goal of preparing low-cost functional food, squid protein hydrolysate (SPH) was extracted from four squid species by protease treatment. Peptides are the major components (approximately 84-88%) of the SPH. The stabilization effects of 5% SPH (dried weight/wet weight) on the state of water and the denaturation of frozen lizard fish Saurida wanieso myofibrillar protein (Mf) were evaluated on the basis of desorption isotherm curves with respect to Ca2+-ATPase inactivation and the presence of unfrozen water, which was determined using differential scanning calorimetry during dehydration, and the effects were compared with those of sodium glutamate. The Mf with SPH was found to contain higher levels of monolayer and multilayer sorption water, resulting in decreased water activity and Ca2+-ATPase inactivation. The amount of unfrozen water in Mf with SPH increased significantly, suggesting that the peptides of SPH stabilized water molecules on the hydration sphere of Mf, which maintained the structural stability of Mf, and therefore suppressed dehydration-induced denaturation. The effect by SPH was less than that by sodium glutamate.
