小麦麸皮水溶性阿拉伯木聚糖调控热诱导面筋蛋白聚集行为机制

Heat-induced polymerization of gluten protein during cooking stage is a key factor in determining the edible quality of wheat-based food. Water-extractable arabinoxylan (WEAX) from wheat bran can enhance the steamed bread quality by regulating the heat-induced polymerization behavior of gluten protein, and the regulatory degree depends on the structural composition of WEAX. However, the regulatory mechanism remains unknown. Taking gluten with the addition of WEAX in different structural composition as the experimental material, the current project intends to study its strength, extensibility, viscoelasticity, creep-recovery and thermal characteristics from the view of glutenin-gliadin polymerization during thermal treatment, and the varying process of gluten functional properties will be clarified; The particle size distribution, voluminosity, microstructure and apparent morphology will be evaluated to elucidate the varying features of microscopic morphology in gluten; The molecular weight, molecular size, subunit composition, secondary structure, hydrophobic group and driving force of the protein fractions will also be analyzed to establish the varying model of gluten structure. The effect of WEAX with different structural composition on the gluten polymerization at the different levels will be comprehensively analyzed to elucidate the regulatory rules of WEAX on the heat-induced polymerization behavior of gluten protein. On this basis, the effect of WEAX on water migration of gluten, as well as the direct interacting subunits and groups will be investigated to clarify the acting mode of WEAX on gluten protein. The regulatory mechanism of WEAX on the heat-induced polymerization behavior of gluten protein will thus be revealed. This research achievement will compensate the regulatory mechanism of WEAX on gluten characteristics and thus contribute to providing scientific basis for enhancing the quality of wheat-based product.

面筋在熟制阶段的聚集作用是影响面制品食用品质的关键因素。小麦麸皮水溶性阿拉伯木聚糖（WEAX）可通过调控热诱导面筋聚集行为提升馒头品质，且调控程度与WEAX结构组成有关，但机制不明。本项目以添加不同结构组成WEAX的面筋为试材，从面筋组分—谷蛋白和醇溶蛋白聚集角度研究其在加热阶段强度、延展性、粘弹性、蠕变-恢复性及热特性，探明面筋宏观功能性变化过程；解析其粒径分布、容积度、微观结构和表观形貌，明确面筋微观形态变化特征；分析组分蛋白分子量、分子尺寸、亚基组成、二级结构、疏水基团和作用力，建立面筋分子结构变化模型；综合分析不同结构组成WEAX在上述层面上对面筋聚集影响，阐明其调控面筋聚集行为的规律。在此基础上，研究WEAX对面筋水分迁移影响及其与面筋直接作用的亚基和基团，明确其对面筋作用的方式，揭示WEAX调控热诱导面筋聚集行为机制，以此完善其调控面筋品质理论，为面制品质量提升提供科学依据。

作为麦麸膳食纤维的重要成分，水溶性阿拉伯木聚糖（WEAX）可与面团主要加工组分面筋蛋白作用显著提升面制品的食用品质。本项目以不同结构组成WEAX的面筋为试材，从面筋组分—谷蛋白和醇溶蛋白聚集角度系统研究了WEAX调控热诱导的面筋蛋白聚集行为机制。主要研究结果如下：（1）在宏观层面，高分子量和低分子量WEAX均可通过促进谷蛋白和醇溶蛋白的聚集行为来提高面筋粘弹性和热稳定性，其中低分子量WEAX作用效果更显著，两种分子量WEAX对面筋蛋白的热特性无显著作用差异。（2）在微观层面，添加低分子量WEAX的面筋蛋白的粒径在加热过程中的增幅最大，两种WEAX诱导醇溶蛋白分布不均匀，并且促进谷蛋白网络结构增强，使得蛋白表面更为光滑。（3）在分子层面，两种WEAX显著促进了谷蛋白和醇溶蛋白聚合物的形成；低分子量WEAX更有效地通过促进α-、γ-醇溶蛋白聚集，从而影响醇溶蛋白和谷蛋白分子间交联，而高分子量WEAX则将谷蛋白和麦醇溶蛋白之间起始聚集温度从95℃提前至70℃；WEAX 可通过氢键作用Trp和Tyr残基，并诱导二硫键构象转化为不稳定的t-g-g和t-g-t构象。（4）对比研究不同阿魏酸含量的WEAX对面筋热诱导聚集行为研究表明，阿魏酸基团有利于促进谷蛋白和醇溶蛋白的聚集行为，且促进了α-螺旋转变成β-折叠和分子间β-折叠，有利于保持面筋蛋白二级结构的稳定性，从而有助于提升面筋蛋白粘弹性。项目研究成果可完善WEAX调控面筋品质理论，为面制品质量提升及其功能性配料研发提供科学依据，同时对推动高纤面食产业的发展具有积极意义。