Effect of Gallic Acid on Gel Properties and in Vitro Activity of Digested Products of Nemipterus virgatus Surimi

In this study, the effect of addition of gallic acid (GA) (0%–0.25%) on the gel properties, microstructure and intermolecular forces of surimi from Nemipterus virgatus, prepared by a two-step heating method, was investigated. The surimi was digested under in vitro gastrointestinal conditions and evaluated for antioxidant activity and cholesterol-lowering activity in order to determine the improving effect of GA addition on the functional properties of surimi gels. The results showed that addition of GA could improve the gel strength and texture properties, but worsen the whiteness of surimi gels. Surimi gels with 0.15% of GA had the best texture properties and highest whiteness and water-holding capacity as well as a dense microstructure, and the major chemical force maintaining the gels was disulfide bonds. The results of digestion in vitro showed that addition of GA increased the protein digestibility of surimi gels (P < 0.05), and enhanced the biological activity of the digested products (P < 0.05). The scavenging percentages of the digested surimi gel with 0.15% of GA toward 1,1-diphenyl-2-picrylhydrazine (DPPH) radical, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical and hydroxyl radical were increased all 80% (P < 0.05), and the inhibition percentages toward cholesterol esteraseand cholesterol micellization were increased to 50.82% and 41.88%, respectively (P < 0.05). These results indicated that surimi with added GA still retained its biological activity after heat treatment and in vitro digestion. Therefore, addition of an appropriate amount of GA can effectively improve the heat-induced gel properties of N. virgatus surimi while retaining its functional properties, which provides a basis for the development of new functional surimi products.