脱脂豆粉中碳水化合物分子定向修饰对豆胶性能的协效作用与机理研究

Preparing environmentally friendly soy-based adhesives (SBAs) using defatted soy flour (DSF) and improving its water resistance via different types of modification techniques of soy protein were extensively investigated. However, in addition to protein, DSF also consists of 40% (w/w) carbohydrate, which negatively affects the properties of SBAs. Modification and utilization of these component were rarely reported previously. The aim of this project was to prepare boiling-water-resistant SBA by using all the components of DSF; and the water resistance bonding strength of SBAs were synergistically improved by targeted modification of carbohydrates in DSF. Physical, chemical, and biological approaches will be used to hydrolyze original carbohydrates in DSF into some corresponding micro-molecular. According to the difference of functional groups between micromolecular carbohydrates and soy proteins, micromolecular carbohydrates were then designed to derivative by chemical reaction, which have better reactivity with soy protein as compared to control. The stability of the modified carbohydrates was also investigated. Boiling-water-resistant SBAs were then prepared based on assembly between modified carbohydrates and soy proteins and current soy protein modification techniques. The molecular structure and phys-chemical phenomenon of the products formed during carbohydrate hydrolysis and modification, and also the preparation of boiling-water-resistant SBAs were characterized by XPS, IR, NMR, and ESEM. Based on these characterization results, the mechanism of improving gluability of SBAs by targeted modification of carbohydrate was finally exploited. The results originated from this project will not only be useful to adhesives industry itself, but also can provide theoretical foundation to related industries.

用脱脂豆粉制备环保型木材胶黏剂，对其中的大豆蛋白进行各种改性以提高豆胶的耐水性已有许多研究，但豆粉中还含有约40%的碳水化合物，影响豆胶的耐水性和使用性能，该组分的改性和利用尚未见报道。本项目拟对脱脂豆粉中的碳水化合物分子进行定向修饰，使其与大豆蛋白协效提高豆胶的耐水胶合强度，既充分利用原料，又使豆胶达到耐沸水的性能。项目拟采用物理、化学、生物学方法对脱脂豆粉中的大分子碳水化合物进行水解；再根据小分子碳水化合物与大豆蛋白官能团的差异，设计小分子碳水化合物通过化学反应形成衍生物，提高反应活性；研究碳水化合物定向修饰后溶液中各组分的演变规律；然后结合现有的大豆蛋白改性技术，使碳水化合物与大豆蛋白分子间组装，协效制备出耐沸水型大豆基胶黏剂；采用XPS、IR 、NMR、ESEM等分析手段剖析豆胶制备过程中各产物的结构特征、理化现象，解析定向修饰的碳水化合物提高大豆基胶黏剂耐水胶合强度的机理。

针对脱脂豆粉中碳水化合物在制备大豆基胶黏剂过程中的利用问题。课题对脱脂豆粉组分分别进行修饰并衍生化接枝改性，实现脱脂豆粉全组分利用，制备了耐水性能优异的大豆基胶黏剂。脱脂豆粉的组分分析发现其粗纤维含量远多于葡萄糖等还原糖。脱脂豆粉用Viscozyme L酶在50 ℃，pH 5.2的条件下处理20 min可获得较好的碳水化合物水解效果，胶液中小分子糖类（如葡萄糖）大量增加；Aspergillus niger（NRRL 322）产复合酶处理脱脂豆粉也可迅速提高胶液中的小分子糖类含量，提高固化胶黏剂的耐水性；将脱脂豆粉中碳水化合物分离后用酸水解也可达到酶处理类似的效果。大豆基胶黏剂中小分子糖类比例上升，其固化后的耐水性增强；还原糖通过与大豆蛋白发生美拉德反应，降低胶黏剂固化后的亲水性，提高胶合强度。采用碱对脱脂豆粉中的大豆蛋白进行结构修饰可舒展其球状结构，暴露活性官能团，再以丁烷4羧酸交联可形成大量酯键连接，可进一步提高耐水性能；为先释放大豆蛋白内部官能团，再多位点交联，制备耐水性大豆基胶黏剂提供了思路。酶联合酸盐碱处理脱脂豆粉的方式综合了单独对碳水化合物和大豆蛋白修饰，增加官能团含量的优点，胶液有更多活性官能团，适合于进一步的衍生化改性研究。环氧树脂或苯乙烯可对水解修饰后的脱脂豆粉组分进行有效接枝；当用量为30%时，制备的大豆基胶黏剂在沸水处理3小时后，耐水胶合强度分别为0.95 MPa和1.09 MPa。苯乙烯衍生化改性的大豆基胶黏剂贮存期达到47天，有较好的耐微生物、热稳定性。研究阐明了利用脱脂豆粉全组分制备耐沸水大豆基胶黏剂的机理，为类似生物质基胶黏剂的研究提供了借鉴。项目研究过程发表了11篇论文，其中SCI收录8篇，EI收录2篇，中文核心收录1篇；申请了5件发明专利，授权3件；在国内外学术会议上做了6次会议报告；培养博硕士生2名。