醋酸水溶液体系中玉米醇溶蛋白纤维化分子机制研究

As a natural non-allergenic plant protein, zein can form micro-and/or nano-aggregates with particular structures and functions through molecular self-assembly, which are widely applied in the food industry. The result from our preliminary experiment shows that zein could form filamentous nanofibers in aqueous acetic acid, which is quite different from the previous reports that zein commonly forms spherical nanoparticles in aqueous ethanol. The finding indicates that different solvents would affect the self-assembly behavior of biopolymers. In the current project, the aqueous acetic acid is chosen as the model system and the effects of intermolecular forces mediated by different experimental parameters on zein molecular structure and its fibrillation behavior will be explored. The molecular dynamics simulation techniques will be applied to analyze the formation process of zein fibers and to reveal the fibrillation mechanism of zein in terms of molecular interactions. Based on the glass transition characteristics of zein, the antisolvent precipitation method by adding cold distilled water to the hot aqueous acetic acid of zein is going to be developed for preparing zein nanofibers, and system temperatures will be optimized to achieve the oriented structural design and regulation of zein nanofibers. The relationship between the fiber structure and dough rheological properties of zein will be clarified. The implementation of this project would improve the present available theory of protein fibrillation, and provide a technical support for zein nanofibers to be a new kind of functional food ingredients.

玉米醇溶蛋白为天然非致敏性植物蛋白，通过分子自组装可形成特定结构与功能的微纳米聚集体，在食品领域应用广泛。目前研究多聚焦在乙醇水溶液体系中解析其形成纳米颗粒的自组装特性。申请人新近发现，玉米醇溶蛋白在醋酸水溶液体系中可形成丝状纳米纤维，说明不同溶剂体系对分子自组装行为产生重要影响。本项目以醋酸水溶液为模式体系，探究不同实验参数介导的分子作用力对玉米醇溶蛋白分子结构及其纤维化行为的影响规律，结合分子动力学模拟纤维形成过程，在分子驱动力层面揭示玉米醇溶蛋白纤维形成机制；基于玉米醇溶蛋白玻璃化转变特征，构建热溶冷反法制备玉米醇溶蛋白纳米纤维，通过调节体系温度，实现纳米纤维结构定向设计与调控；深入挖掘玉米醇溶蛋白纤维结构与玉米醇溶蛋白面团流变特性之间的关联，阐明其内在关系。本项目实施不仅可丰富与完善现有蛋白质纤维化基础研究理论，而且为醇溶蛋白纳米纤维作为新型食品功能配料提供技术支撑。

分子自组装是蛋白分子在一定条件下通过非共价相互作用自发形成具有特定结构与功能聚集体的过程，解析该过程对蛋白质的功能及应用研究至关重要。玉米醇溶蛋白是从玉米淀粉加工副产物中提取得到的天然蛋白质，是玉米副产物综合开发利用高附加值产品中的一种。与致敏性小麦蛋白不同，玉米醇溶蛋白为非致敏性蛋白，且具有独特自组装特性、成膜性、生物相容性和可降解性，是公认为安全的食品级原料。本项目以玉米醇溶蛋白为代表性植物蛋白原料，以乙醇水溶液和醋酸水溶液为模式体系，通过控制实验参数，调节分子内和分子间疏水作用和静电作用，发现玉米醇溶蛋白可形成蠕虫状、棒状、丝状纤维等多尺度微纳米聚集体，突破了现有报道玉米醇溶蛋白仅形成单一球形聚集体形貌的局限性，为制备结构多样、功能丰富的新型食品配料奠定理论依据与技术支撑。此外，基于分子工程原理，通过调控玉米醇溶蛋白分子内相互作用和蛋白分子与溶液间相互作用的微平衡，建立了一种自下而上热诱导分子自组装方法，实现了玉米醇溶蛋白分子自组装形貌的定向设计与调控，研制了玉米蛋白面筋、植物蛋白奶酪、脂肪替代等产品，为非致敏性植物基食品开发提供重要技术支撑。围绕上述研究结果，在Food Hydrocolloids等权威杂志上发表SCI第一标注论文5篇，授权发明专利3项。