超声处理及添加蔗糖对明胶/变性淀粉共混体系溶胶-凝胶转变过程流变性质的影响

Effects of Ultrasonic Treatment and Sucrose Addition on the Rheological Properties of Gelatin/Modified Starch Blends during Sol-Gel Transition

摘要:

本文以明胶/变性淀粉共混体系（4.5%/9.0%）为凝胶糖果模型体系，探讨了未经超声处理条件下添加蔗糖（0%~15%，W/W）及10%蔗糖共溶质存在时超声处理（475 W，0~15 min）对其溶胶-凝胶转变过程流变黏弹性模量（G′、G″）、即时凝胶结构化速度(vg)及微观结构等凝胶性质的影响。结果表明：未经超声处理时，共混体系的G′、vg值随蔗糖共溶质浓度（0%~10%）增加呈增加趋势，但凝胶活化能(Ea)值被显著降低，并形成表面更均匀平整的微观结构；10%蔗糖共溶质场中，与未经超声对照样相比，超声处理5 min后，降温程序末共混体系的G′、vg值分别由6482.40 Pa、7.01 Pa/min骤降至1378.90 Pa及2.94 Pa/min，降幅依次为78.73%及58.06%，而凝胶化的Ea值则由116.23 kJ/mol显著增加至319.42 kJ/mol（p<0.05），随超声时间延长，进一步加剧了G′、vg及Ea的上述变化趋势，伴随凝胶微观结构的孔隙和不规则度均呈上升趋势，表明超声可抑制低浓度蔗糖共溶质改善凝胶强度及性能的作用；研究结果可用于指导优化明胶凝胶糖果溶胶-凝胶工序及产品性能。

Abstract:

The effects of sucrose addition as co-solute (0%~15%, W/W) without ultrasonic treatment and in the presence of 10% sucrose with ultrasonic treatment (475 W, 0~15 min) on the viscouselastic modulus (G′,G″), the gel structure formation instant gelation velocity (vg) of the gelatin/modified starch blends (4.5%/9.0%) as gel candy model system during sol-gel transition and gel properties such as microstructure were investigated. Results showed that, in the presence of relatively low concentration of sucrose (0%~10%), G′ and vg values increased significantly, while the activation energy (Ea) values of GL/MS blends reduced significantly. Formation of more uniform surface microstructure was found. Compared with the controls without ultrasonic treatment under 10% sucrose cosolute environment, G′, vg of GL/MS blends of sample with ultrasonic treatment 5 min decreased sharply from 6482.40 Pa, 7.01 Pa/min to1378.90 Pa and 2.94 Pa/min, corresponding the decreased amplitude as 78.73% and 58.06%, respectively, while the gelation Ea values significantly increased from 116.23 kJ/moL to 319.42 kJ/moL (p<0.05). The change trends of G', vg, and Ea were further exacerbated with the extension of ultrasonic treatment time, while the microstructure porosity and irregular degree increased, suggesting that ultrasonic treatment could suppress the improve effect of low concentration sucrose on the formation and performance of the blend gels. These results would apply to optimize the sol-gel process and product performance of gelatin type gel candy.