Effect of microwave-ultrasonic combination treatment on heating-induced gel properties of low-sodium tilapia surimi during gel setting stage and comparative analysis

To improve the gel properties of low-sodium tilapia surimi, the effects of microwave-ultrasonic, single microwave, single ultrasonic and traditional water-bath heating treatments on the characteristics of low-sodium tilapia surimi gel in the gel setting stage were investigated in this study. Compared with other treatment groups, the water-bath heating and microwave–ultrasonic-assisted heating (WB-MW/US) + 1.5% NaCl group had higher gel strength (403.30 g cm) and water-holding capacity (87.88%). LF-NMR and CD spectrum analysis indicated that microwave and ultrasonic combination increased the degree of protein cross-linking and moisture proton density. In addition, microwave and ultrasonic combination had minimal effect on the secondary protein structure. WB-MW/US+1.5% NaCl group had more β-sheet (27.80%) and random coil content (22.30%), resulting in a uniform and dense spatial network structure of the low-sodium tilapia surimi gel. The results indicated that the microwave-ultrasonic combination treatment could be used as an efficient strategy for the production of new energy, low-sodium surimi gel products.