引入谷氨酰胺转氨酶(transglutaminase,TG酶)对明胶进行改性制备微凝胶,通过对不同TG酶交联度明胶微凝胶Pickering乳液进行流变学、电位测试以及微观结构观察,重点研究了不同TG酶交联度对乳液流变学特性的影响。结果显示,TG酶添加量可以有效调控明胶微凝胶的交联度(1.85%~12.25%);流变结果表明,随着交联度的提升,表观黏度和屈服应力值(2.10~4.47 Pa)均上升,损耗因子减小,温度循环测试回复率从28.2%上升至75.6%。综合流变学测试结果表明当交联度达到6.85%以上,明胶微凝胶稳定的乳液连续相形成了更强的凝胶网络结构。此外,乳液体系的ζ电位随着交联度的增大而增大,静电排斥作用增强,有利于连续相网络结构的形成;微观结构显示,随着交联度的增大,油水界面处的吸附蛋白增多并形成致密的界面膜,液滴之间相互作用增强形成更强的凝胶网络结构,从而在连续相的角度使乳液稳定性提升。因此,经过TG酶交联的明胶微凝胶Pickering乳液更为稳定,为明胶微凝胶在食品中的应用提供了理论基础。
Transglutaminase (TG enzyme) was introduced to modify gelatin to prepare microgels, rheology, ζ potential and microstructure of gelatin microgels stabilized Pickering emulsions with different TG enzyme crosslinking degrees were carried out to study the effect of different TG enzyme crosslinking degrees on the rheology properties of emulsion.The results revealed that the crosslinking degree of gelatin microgels (1.85%-12.25%) can be effectively regulated by TG enzyme addition amount.Rheological results demonstrated that, the apparent viscosity and yield stress (2.10-4.47 Pa) both increased, the loss factor decreased, and the recovery rate of temperature cycle test increased from 28.2% to 75.6% with the increase of crosslinking degree.The rheological results indicated that the continuous phase of gelatin microgel stabilized emulsions formed a stronger gel network structure when the crosslinking degree exceeded 6.85%.In addition, the ζ potential of the emulsion increased with the increase of crosslinking degree, implying the enhancement of electrostatic repulsion between droplets, and the higher electrostatic repulsion was conducive to the formation of continuous phase network structure.The results of emulsion microstructure showed that with the increase of crosslinking degree, the interfacial protein increased and formed a dense interfacial film, and the interaction between droplets was enhanced to form a stronger gel network structure, thus improving the stability of the emulsion in the perspective of continuous phase.Therefore, the TG cross-linked gelatin microgel Pickering emulsions are more stable, which provides a theoretical basis for the application of gelatin microgel in food.
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