Effect of microwave heating on the low-salt gel from silver carp (Hypophthalmichthys molitrix) surimi

Gels from silver carp (Hypophthalmichthys molitrix) surimi were obtained using microwave (MW) heating (15 W/g power intensity for 20–80 s) at different levels of salt (0 g/100 g, 1 g/100 g, or 2 g/100 g). And the gel heated by MW was compared with the gel obtained by conventional water-bath heating (85 °C for 30 min). The gel strength increased when the salt level was increased. The mechanical and functional properties of non-salted, low-salt and regular-salt products were improved by MW heating for 60 s and 80 s, significantly (p < 0.05), except for the cook loss. The content of TCA-soluble peptides indicated that the MW heating inhibited the autolysis of proteins significantly (p < 0.05) during gelling. The SDS-PAGE and total content of –SH group proved that MW enhanced the cross-linking of proteins effectively through disulphide bonds and non-disulphide covalent bonds. The microstructure of the samples revealed that a fine compact network, with particles of protein aggregates, was formed in the low-salt gels (1 g/100 g) heated by MW for 60 s. All of these properties might be responsible for the formation of a superior textural low-salt gel induced by MW.