LAOS法表征海藻多糖食品水凝胶的非线性流变行为：条件、机理和应用

High efficiency processing of seaweed polysaccharide hydrogels needs profound understanding of their rheological properties, and food rheology, especially nonlinear rheology, can truly response the food molecules interaction and microstructures changes under large shear strain, which is much closer to the industrial food processing. Large amplitude oscillation shear (LAOS) had effectively characterized nonlinear rheological properties of melt, and also established some relatively perfect theories and models. While, LAOS characterization of food hydrogel has started in foreign country, but rarely reported in China. In this project, we will systematically characterize the nonlinear rheological behaviors of seaweed polysaccharide food hydrogel by LAOS, and through the data analysis by Lissajous curves, stress decomposition and Fourier Transform rheology, the nonlinear behaviors of these hydrogels will be visually, quantitatively characterized. Furthermore, based on the relatively mature linear rheological theories of hydrogels and the well-build models of melts, we will clarify the nonlinear rheological properties and associated microstructures changes under large shear strain, meanwhile, try to establish quantitative characterization of nonlinearity by LAOS behaviors. Lastly, through the theoretical analysis and computer simulation, we hope to establish an effective theory and model of food hydrogel to provide theoretical support for food gel processing. In addition, this research will enriched the LAOS study of food hydrogels and broaden the research areas of the course of physical properties of food.

高效率的海藻多糖食品水凝胶加工需要深刻知悉其流变行为，而食品流变学，尤其非线性流变学，能够真切地反应食品在大应变下的分子结合状态及组织结构，更接近实际食品加工过程。大幅震荡扫描（LAOS）已有效地表征了熔体非线性流变特性，且已经建立了相对完善的理论和模型。LAOS表征食品水凝胶在国外已起步，而国内鲜有报道。本研究将利用LAOS法系统地表征海藻多糖食品水凝胶非线性流变行为，通过Lissajous曲线、应力分解及傅里叶变化等解析LAOS数据，可视化、数据化地表征多糖水凝胶的非线性行为。结合相对成熟的线性流变学理论及完善的熔体LAOS模型，阐明食品水凝胶在大应变下的流变行为以及与之相关联的微观结构变化，构建非线性特性与LAOS之间的定量关系。通过理论分析和电脑模拟，建立有效的模型理论，以期为食品水凝胶的加工提供理论支持。此外，该研究将丰富食品水凝胶LAOS研究，拓宽食品物性学课程的发展。

食品亲水胶体在食品加工和物性改良中具有重要的作用，尤其是在未来食品人造肉和老年护理食品中，应用前景广阔。食品胶体流变学，尤其是非线性流变学，能够更切实的反应食品在大应变下的结构变化，更接近食品加工过程。大幅震荡扫描（LAOS）已有效地表征了熔体非线性流变特性，且建立了相对完善的理论和模型，LAOS法表征食品水凝胶在国外已起步，而国内鲜有报道。本研究通过半透膜、离子交换和高分子膜截留法制备了分子量分布更窄的Na型kappa-和iota-卡拉胶，并对单一和混合多糖体系的线性和非线性流变学特性进行了系统表征，尤其是LAOS行为表征。通过Lissajous曲线、应力分解及傅里叶变化等解析了LAOS数据，阐明了多糖亲水胶体的大应变流变学性质。同时，研究了多糖和蛋白质（大豆分离蛋白）混合体系的线性和非线性流变学特性，尤其是大应变流变学特性。利用激光共聚焦显微镜和SEM观察了复合亲水胶体的微观结构。建立了LAOS法表征食品亲水胶体流变学特性的测试及数据解析方法，系统分析了LAOS测试相关数据与亲水胶体流变行为的关系；根据显微观察结构，阐明了食品亲水胶体的大应变特性与微观结构的关系。该研究丰富了食品亲水胶体的大应变理论研究，建立了相对稳定的检测和分析方法，为食品亲水胶体的加工提供了一定的理论支持，同时拓宽了食品物性学的范畴；该项目的开展在食品加工领域具有一定的应用价值。