全麦体系阿拉伯木聚糖对面筋蛋白网络形成的干预与调节机制

Arabinoxylan（AX）is one of the most important dietary fibers in whole wheat flour which reaches up to 6%-8% level. According to the earlier reports and our research, AX had significant effects on the structure of gluten network which mostly determine the qualities of end-products, due to its high water holding capacity, high viscosity and oxidative gelation. However, most of the previous studies were based on ordinary or white flour, and the products were mainly bread. Compared to white flour, the total content of AX increased 3-4 times and the insoluble AX up to 85% in whole wheat flour. How does AX effect on the development of gluten networks, and on the qualities of Chinese traditional staple(steamed bread), remains lack of research . This study intends to investigate the major procedure and different processing conditions of whole wheat products, including wheat raw material, milling, aids (hydrolase, oxidase), dough kneading, fermentation, steaming, and to compare the different systems(AX or/and Pro model and common flour) with whole wheat. The changes about AX in its molecular structure, physicochemical properties, meanwhile, the related changes of gluten protein in its micro- and macroscopic network morphologies, molecular structure and composition, and of the products characteristics will be analyzed comprehensively. Then, the influence of AX from whole wheat flour to the gluten network development and the inherent mechanisms could be revealed. The results may provide scientific evidences to improve the qualities of Chinese whole wheat staple products from the point of AX, the most important dietary fiber in whole wheat flour.

阿拉伯木聚糖（AX）是全麦面粉中的主要膳食纤维组分，含量高达6%～8%。根据以往研究，AX的高持水性、高粘度以及氧化凝胶性质对决定面制品品质的面筋网络结构有显著影响，但之前研究主要基于普通小麦面粉，对象多以面包为主。在AX总量提高3～4倍、不溶性AX高达85%的全麦体系中，AX对面筋网络结构的干预作用，以及对我国传统主食馒头品质的影响目前尚缺乏科学研究。 本研究拟从原料品种、磨粉、加工辅料（酶制剂）、和面、发酵、熟化等涉及馒头加工的主要工艺环节入手，通过将全麦体系与模型（AX，Pro，AX－Pro）、参照（普通面粉）体系的对比研究，系统解析不同体系、加工过程中AX分子结构、物化特性的变化，并由此带来的面筋蛋白聚合网络结构、蛋白分子与化学组成、面团及面制品品质等的变化，进而揭示全麦体系中AX对面筋蛋白网络的干预与分子调控机制，研究成果有望为从AX角度改善我国全麦主食产品品质提供科学依据。

阿拉伯木聚糖（AX）是全麦粉中重要的膳食纤维，含量高达6%～8%，较普通小麦粉提高3～4倍，且85%以上为不溶性AX。本项目从小麦品种、磨粉、酶制剂及馒头加工的主要工艺环节入手，通过将全麦体系与模型体系的对比研究，系统解析全麦面团和馒头体系中AX分子结构、物化特性的变化，并由此带来的面筋蛋白聚合网络结构和面制品品质等的变化，进而揭示全麦体系中AX对面筋蛋白网络的干预与分子调控机制。项目的重要结果和数据如下：1）收集国内外10个小麦品种，通过聚类分析筛选出JN17、APH、JQ5 3个代表品种进行全麦面团和馒头加工适宜性研究。全麦馒头品质由高到低依次为APH＞JQ5＞JN17，其品质的差异与面团的筋力强弱、延展性、P/L值及气体释放能力有关。2）对于不同粗细度麸皮（D50值：285.0、186.7、75.7 µm）全麦粉，中等粒径（D50：186.7 µm）麸皮全麦粉所制得的馒头品质最好；麸皮过粗口感粗糙；麸皮粒径减小，面团吸水率增大、稳定时间及弱化度下降。3）戊聚糖酶（Pn）、葡萄糖氧化酶（Gox）、复合酶（Pn-Gox）在适宜添加量下均显著改善了全麦馒头的品质，且复合酶使作用效果更佳。4）从全麦粉中提取可溶（WEAX）及不可溶性阿拉伯木聚糖（WUS），发现WUS纯度低于WEAX，但得率、阿魏酸含量、阿拉伯糖/木糖比（Ara/Xyl）均高于WEAX。Pn可催化WEAX的降解，并伴随着WEAX重均分子量、黏度的降低。提高Pn用量，WUS增溶程度不断增加、但增速减缓；Pn优先作用于WUS中Ara/Xyl小的位置。Gox可促进WEAX氧化凝胶的形成，且Gox量增加，凝胶反应加快、凝胶时间显著缩短，网络交联程度增加。5）构建WUS-面筋蛋白-淀粉模拟全麦面团，发现Pn对WUS的增溶作用引起面团中谷蛋白大聚体（GMP）和自由巯基（SHf）含量的显著增加；麦谷蛋白溶解性显著降低；高剂量Pn使醇溶蛋白的溶解性增加；面团结构疏松，面筋网络充分延展，Pn过量时面筋网络发生断裂；面筋蛋白二级结构β-折叠减少，面团粘弹性降低。Pn与Gox复合使用时，Pn能使面团内GMP和SHf含量显著性增高；麦谷蛋白和醇溶蛋白溶解性均显著性增加；面筋网络结构充分延展；面筋蛋白β-折叠减少、面团粘弹性降低。