新型W/O盐卤凝固剂对大豆蛋白凝胶中水分变化的影响

Effect of Novel W / O Bittern Coagulant on the Change of Water in Soy Protein Gel

探讨新型油包水(W/O)盐卤凝固剂对大豆蛋白凝胶中水分变化的影响。利用差示量热扫描仪(DSC)和低场核磁共振(LF-NMR)来研究豆腐凝胶过程中水分的变化。结果表明,在豆腐凝固的过程中,总水分含量下降,自由水下降,结合水含量总体呈现上升趋势,豆腐凝胶结构中的水分自由度在不断减少。与传统盐卤凝固豆腐相比,新型W/O盐卤豆腐凝胶在同一阶段的自由水含量较高,弛豫时间较长,W/O凝固剂的缓释可以改善豆腐的质量。此外,WPI含量不仅对乳液稳定性起作用,而且会改善豆腐品质。在0.5%WPI W/O乳液作为凝固剂得到的豆腐样品核磁共振成像中氢质子的密度最大,说明WPI可以提高豆腐的持水性和品质,因此可将0.5%WPI制备的W/O乳液凝固剂作为豆腐生产用凝固剂。

The objective of th study is to discuss the effect of novel W/O bittern coagulant on the change of water in soy protein gel. DSC and Low -field NMR were two novel techniques which have been adopted here to explore the water properties during tofu coagulation process. The results showed that during the coagulation, the amount of the total water and free water decreased while the amount of bound water increased generally. This demonstrated that the free degree of water had decreased. Compared with traditional bittern tofu, the novel W/O bittern coagulated tofu contained more water; and the relaxation time was longer on same condition. This can be attributed to controlled - re- lease properties of W/O emulsion coagulants, and therefore leads to higher water - holding of tofu samples. Besides, the content of WPI in the W/O emulsion also have an important role in improving the stability of W/O emulsion coag- ulan, the water holding capacity, as well as the quality. The observation by MRI has indicated that the hydrogen pro- ton intensity in 0.5% WPI W/O emulsion coagulanted tofu sample was the highest which demonstated that 0.5% WPI W/O emulsion coagulant did have the ability to hold more water and improve the qulity of tofu. Therefore, 0.5% WPI W/O emulsion can be selected as the suitable controlled -release emulsion coagulant in tofu producing processing.