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 (15W/g power intensity for 20–80s) at different levels of salt (0g/100g, 1g/100g, or 2g/100g). And the gel heated by MW was compared with the gel obtained by conventional water-bath heating (85°C for 30min). 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 60s and 80s, 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 (1g/100g) heated by MW for 60s. All of these properties might be responsible for the formation of a superior textural low-salt gel induced by MW.