Abstract: This study investigated the effects of different concentrations (0.1%, 0.3%, 0.5%, 0.8% and 1.0% by mass relative to shrimp meat) of hyaluronic acid (HA) on the gel and physicochemical properties of surimi made from Litopenaeus vannamei. The results showed that adding a certain amount of HA improved the textural characteristics, gel strength, brightness and whiteness of shrimp surimi gel, promoted the transformation of free and immobilized water into bound water, and increased the water-binding characteristics and water-holding capacity. Rheological analysis showed that addition of a certain amount of HA improved the storage moduli of shrimp surimi, but low concentrations of HA could have adverse effects on the apparent viscosity. Chemical force analysis showed that ionic bonds first decreased and then increased, while hydrogen bonds exhibited the opposite trend with the addition of HA. An appropriate amount of HA could improve hydrophobic interactions but the formation of disulfide bonds from sulfhydryl oxidation was also inhibited by HA. Moreover, HA could interact with shrimp surimi proteins, inhibit the formation of protein polymers, change the conformation of proteins, and promote the transformation of the secondary structure of proteins from α-helix to β-structure and random coil. The microstructure of shrimp surimi gel was improved by adding an appropriate amount of HA, becoming more uniform and denser. Among all samples with different levels of HA, shrimp surimi gel with the addition of 0.8% HA had the highest hardness, gumminess, chewiness, gel strength, storage modulus and the densest microstructure, and its water-holding capacity significantly improved when compared with that of the control group (P < 0.05). However, the textural characteristics, gel strength, water-holding capacity and storage modulus of shrimp surimi gel with 0.1% HA were lower than those of the control group, and the microstructure was looser.

Key words: Litopenaeus vannamei, shrimp surimi, hyaluronic acid, gel properties, physicochemical properties