Effects of microwave combined with conduction heating on surimi quality and morphology

Past studies have reported that microwave heating (MW) usually leads to higher cooking loss and texture deterioration in surimi processing. The objective of this study was to evaluate the effects of different microwave heating methods on surimi gel properties. Compared to traditional two steps water bath heating method (WB), using microwave heating to replace the first step of water bath heating would lead to the deterioration of surimi quality. By contrast, using microwave heating to replace the second step of water bath heating could significantly improve gel strength and water holding capacity. Microwave heating contributed to gelation and promoted the cross-linking of proteins via disulfide and non-disulfide covalent bonds. From scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), microwave heating coupled to the traditional water heating method resulted in more compact network structures. Although the favorable gel strength was obtained by both the time-dependent mode and temperature preservation mode, CLSM three-dimensional micrographs revealed that the time-dependent mode contributed to shrinkage and rough surfaces. Therefore, the rapid heating rate of microwave results in the aggregation of proteins with superior texture, and the temperature-preservation mode results in desirable morphology and improved texture.