葡萄糖氧化酶对全麦面团中面筋蛋白网络的劣变作用及机制

Whole-wheat food contains several kinds of physiological active substances. Long-term intake of whole-meal food can reduce the incidence of cardiac-cerebral vascular diseases. Whole-wheat food has become a hotspot of research in recent years. Many studies have shown that glucose oxidase can substitute potassium bromate, reinforce the cross-linking between protein molecules and promote the strength of gluten network in wheat endosperm dough. However, our previous study showed that glucose oxidase could lead to the increase of porous structure and the reduction of structural continuity in the gluten matrix of whole-wheat dough. The cause and formation mechanism of this phenomenon have been never reported. In the study, whole-wheat dough is considered as the object of the research, the microscopic characteristics for the adverse effects of glucose oxidase on the gluten network in whole-wheat dough are represented by the features of moisture migration, molecular dimension, and chain conformation using the techniques of MRI, AFM, and SEC-LLS. In order to investigate the impact of the main components from wheat bran on the deterioration effect of glucose oxidase, the proportional reconstitution method is adopted, and the rheological properties and microstructural characteristics of whole-wheat dough are also analyzed. Additionally, the relationships between free radicals, free sulfhydryls, disulfide bond and gluten network are investigated to demonstrate the coupling effect of glucose oxidase, peroxidase, and lipoxidase, then indicate the mechanism for the deterioration effect of glucose oxidase on the gluten network of whole-wheat dough. The objective of the study is to establish the scientific basis for the quality regulations of whole-wheat dough.

全麦食品含有多种微量生理活性物质，长期摄入可减少心脑血管疾病的发病率，近年来成为研究热点。已有研究表明葡萄糖氧化酶可替代溴酸钾，在胚乳面团中促进蛋白质分子间的交联，提高面筋强度，而在前期研究中我们发现，葡萄糖氧化酶会造成全麦面团中面筋蛋白网络的中空结构增加，结构连续性下降，该劣变作用的产生原因和形成机制尚未见报道。本研究以全麦面团为研究对象，采用MRI、AFM、SEC-LLS等技术，从水分迁移状态、分子尺寸、链构象等微观特征的角度剖析葡萄糖氧化酶对全麦面团中面筋网络的劣变作用；运用等比例回添的方法，并结合面团流变学特性、微观结构特征等，探讨麦麸中主要组分对该劣变作用的影响；通过分析自由基、二硫键和戊聚糖氧化交联程度等与面筋蛋白网络的相互关系，研究葡萄糖氧化酶与体系中内源氧化酶类的耦合效应，从而揭示葡萄糖氧化酶对全麦面团中面筋蛋白网络的劣变机制。本研究将为全麦面团的品质调控奠定理论基础。

全麦食品因含有大量的膳食纤维和微量生理功能性物质近年来成为研究热点，长期食用全麦制品可减少心脑血管疾病的发病率。已有研究表明葡萄糖氧化酶（GOX）在胚乳面团中可促进蛋白质分子间的交联从而形成更加致密的面筋蛋白网络结构，而我们前期的研究发现GOX会造成全麦面团产生劣变，但其机制尚未明确。本项目以全麦面团为研究对象，探究了全麦面团的面筋网络结构特征及GOX对全麦面团面筋网络的作用特点，发现面团加水量是GOX产生劣变作用的主要因素，当加水量较低时（35-40%），GOX对全麦面团及面条制品呈现劣变作用；当加水量较高时（60-80%），较高的GOX添加量（5-10 u/g）对全麦面包面团具有改善作用，酶添加量和麦麸粒径也是影响酶对面团调控作用的主要因素；分析了麦麸主要组分如纤维素、戊聚糖和阿魏酸等对酶在全麦面团中作用的影响机制，主要采用等比例回添的方法，分析面筋网络形成过程中自由巯基的变化，并结合面团机械学性质和水分分布特征，结果表明麦麸主要组分对酶作用的影响不同，纤维素的影响主要是因为空间阻碍作用，而戊聚糖和阿魏酸的影响机制更为复杂；研究了GOX与体系内含氧自由基与戊聚糖氧化交联程度的关系，GOX添加量的增加会促进全麦面团体系中含氧自由基的增加，当面团加水量增加，含氧自由基含量减少，当面团加水量减少时，含氧自由基含量增加；阿魏酸会增加阿拉伯木聚糖氧化交联程度，当其氧化交联程度增加时，面筋蛋白网络致密性下降，不同GOX添加量也会造成阿拉伯木聚糖氧化交联程度的变化。本项目探明了GOX对全麦面条面团面筋蛋白网络的劣变作用和对全麦面包面团的调控作用及微观特征，阐释了纤维素、戊聚糖、阿魏酸等麦麸主要组分对GOX在全麦面团中作用的影响机制，揭示了全麦体系中GOX对面筋蛋白网络形成的作用机制。本项目的实施为全麦面团的品质调控奠定理论基础。