采用扫描电镜(SEM)、质地剖面分析(TPA)及动态流变技术研究卤水及不同油包水(W/O)乳液凝固剂对大豆分离蛋白(SPI)冷凝胶微观结构及流变特性的影响。流变结果表明,弹性模量(G’)的变化高度依赖W/O乳液中的镁盐释放速度。随着反应时间的延长,G’值不断增大,与传统卤水相比,新型W/O乳液凝固剂延长了冷凝胶的凝固时间,在凝胶形成过程中,W/O乳液对镁盐起到了缓释作用。对比不同W/O乳液凝固剂发现,含有乳清分离蛋白(WPI)的乳液形成SPI冷凝胶的时间更长,而且弹性模量值更小。此外,电镜结果表明W/O乳液凝固剂能显著降低冷凝胶的硬度并改善蛋白凝胶的网络结构,使SPI冷凝胶具有更小的网孔孔隙和更加均匀的网状结构。
Scanning electron microscopy (SEM), texture profile analysis (TPA) and dynamic rheology technique were applied to investigate the effect of traditional bittern and different water in oil (W/O) emulsion coagulants on the rheological properties and microstructure of cold-set SPI gels. Rheological tests suggested that the development of the mechanical moduli (G') of these SPI gels was highly dependent on the release rate of magnesium salts from W/O emulsions. The values of G' in all cold-set SPI gels gradually increased with the extension of time and W/O emulsion coagulants prolonged the solidification time of cold-set SPI gels in comparison with traditional bittern coagulant. This could be attributed to the controlled-release properties of W/O emulsion coagulants. In addition, cold-set SPI gel prepared with W/O emulsion coagulant containing WPI exhibited a longer solidification time and a lower value of G' than W/O emulsions without WPI. Cold-set SPI gels induced by W/O emulsion coagulants had better mierostructure than that of traditional bittern coagulant as shown by SEM results, which elucidated that W/O emulsion coagulants could obviously decrease the strength of cold-set SPI gels and produce protein gels with smaller pores and more homogeneous network structure.