臭氧处理对新收获小麦面筋品质的改善作用及机理

The freshly harvested wheat does not really get physiologically mature. It is poor in gluten quality and not suitable for utilization. In previous research, we noticed the improving phenomenon of ozone on gluten quality of freshly harvested wheat, but its action rule and mechanism were not entirely understood. In this study, medium and strong-gluten wheat will be used as research wheat varieties, and the freshly harvested wheat will be treated with ozone as grain. Factors affecting gluten quality-improving effect of ozone treatment will be systemically studied. Size-exclusion high-performance liquid chromatography (SE-HPLC), gel electrophoresis, laser particle size analyzer, reversed phase high-performance liquid chromatography (RP-HPLC), infrared spectrometer (IR), and fluorescent probe technique will be used to analyze the ozone-induced change of gluten protein in SDS-extractability, molecular and subunit distribution, glutenin macropolymer (GMP) property, secondary structure, and inner force, in order to interpret the relationship between the structure change of gluten protein and the improvement of gluten quality. Layered milling and histochemical methods will used to investigate the structure change of glutenin protein in different zones of grain during ozone treatment, in order to locate the region where glutenin changes its structure. This research will interpret the improving effect and mechanism of ozone treatment on gluten quality of freshly harvested wheat from the perspectives of macroscopic property-microscopic structure and local-whole relationships. This research has theoretical and practical meaning in prompting the utilization efficiency of wheat and enhancing its quality and will be also beneficial in structure modification and function regulation of other proteins.

新收获小麦在生理上并未真正意义成熟，面筋品质较差，不宜加工利用。前期研究发现，臭氧可改善新收获小麦的面筋品质，但其作用规律及机理并未完全明晰。本项目拟以我国典型中、高筋小麦为研究品种，采用臭氧对新收获小麦籽粒进行处理，系统研究臭氧改善新收获小麦面筋品质的规律及影响因素；运用分子排阻色谱、凝胶电泳、激光粒径分布仪、反相高效液相色谱、红外光谱及荧光探针等技术手段分析臭氧处理前后面筋蛋白SDS可提取率、分子量和亚基分布、谷蛋白大聚体特征、二级结构及内部作用力的变化，探明面筋品质改善与面筋蛋白结构变化的关系；通过分层碾磨和组织化学技术研究臭氧处理中籽粒不同部位麦谷蛋白结构的变化规律，明确麦谷蛋白结构发生变化的主要部位。项目从宏观性质—微观结构及局部—整体关系角度阐明臭氧对新收获小麦面筋品质的改善作用及机理，对提高小麦利用效率和质量具有良好的理论和技术支撑意义，并将惠及其他蛋白的结构修饰与功能调控。

臭氧是一种强氧化剂，在粮食加工、储藏中应用广泛。针对新收获小麦面筋质量较差，不宜加工利用的问题，本项目采用臭氧处理新收获小麦，研究了臭氧对小麦面筋质量与食用品质的影响规律，解析了臭氧处理前后小麦蛋白质的结构变化，探究了臭氧对小麦不同部位麦谷蛋白的影响，并探讨了臭氧对小麦脂质与挥发性成分的影响，以期为臭氧在新收获小麦品质调控中的合理应用提供理论指导。结果表明，低强度臭氧（0.61g/h）处理后，小麦粉面团形成时间和稳定时间均增加；但高强度臭氧处理（3.82g/h）时，处理15min和30min小麦粉的面团稳定时间大幅下降。两种臭氧强度下，臭氧处理小麦粉15min和30min均会显著降低馒头制品的比容，但高强度臭氧处理时下降程度更大。与原小麦粉制作的馒头相比，高强度臭氧处理15min的小麦粉制作馒头的气孔数量显著下降。低强度臭氧处理小麦粉30min能显著提升馒头制品切片亮度；高强度臭氧下，臭氧处理5min时馒头制品切片亮度显著提高，但处理30min时切片亮度显著降低。臭氧处理能促进小麦粉中低分子量蛋白的交联，使其通过二硫键和其他相互作用形成高分子量蛋白聚合体，增加臭氧强度或处理时间均会强化蛋白的交联。臭氧处理小麦籽粒时，皮层对臭氧在籽粒中的渗透有阻碍作用，通过重度剥皮可强化胚乳中麦谷蛋白的氧化。随着臭氧处理时间的延长，低强度臭氧处理小麦粉的脂肪酸值和脂肪酸组成变化不大，但丙二醛含量显著上升。高强度臭氧处理时，随着臭氧处理时间的增加，小麦粉的脂肪酸值和丙二醛含量显著增大，油酸、亚油酸、亚麻酸等不饱和脂肪酸含量减少。与原小麦粉相比，臭氧处理小麦粉中挥发性物质的种类和浓度均有明显变化。高强度臭氧处理15min或更长时间的小麦粉与低强度臭氧处理的小麦粉在挥发性成分上差异较大。