红薯内源非淀粉多糖水解酶的分离鉴定及“红薯芽”制备

Hydrolyzation of non-starch polysaccharides such as pectin and cellulose contained richly in sweet potato tubers using special enzymes will be helpful to reduce the the viscosity of the medium, which is considered as a technical problems in need of solution in productions of food ingredients and bulk chemicals fermented from sweet potato tubers. Our previous studies suggested that some hydrolases for polysaccharides such as pectinase or cellulase existed in germinated sweet potato tubers. In this research, isolation and purification of proteins which can catalyze hydrolysis of such polysaccharides will be implemented through AKTA Protein Workstation and chromatographies, then the analysises of essential characteristics in protein and enzyme kinetics of these isolated proteins will be followly carried out for identfications of these proteins.Base on the above mentioned works,the rules and effects of environmental factors and operating conditions on activities of hydrolases for polysaccharides in germination and drying and storage processes will be studied, and optimized conditions for germination and storage and drying for sweet potato buds will be set up through Uniform Design method. The optimization of reaction conditions for hydrolysis of raw sweet potato using sweet potato buds as catalytic agent will be carried out using Response Surface Methodology. The achievements of this project will broaden the understanding of hydrolases for no-starch polysaccharides in sweet potato tubers and provide novel technology for pretreatment of raw sweet potato material in food and chemical fermentation industries.

红薯茎块中果胶等非淀粉多糖含量较高，开发针对性强的酶制剂，通过预处理降低培养基粘度是红薯原料生产食品原料、大宗化学品等发酵过程急需解决的技术难题。前期研究发现发芽红薯茎块中含有能够降解果胶、纤维素等非淀粉多糖的酶类。项目研究拟利用AKTA蛋白质工作站，结合层析等手段分离纯化红薯茎块中具有果胶、纤维素等非淀粉多糖降解活性的蛋白组分，利用序列分析、质谱和光谱等手段对活性组分的蛋白结构进行表征；分析活性组分的酶学和反应动力学参数；以此为基础，对活性蛋白质进行鉴定、分类；系统研究"红薯芽"萌发、干燥和储存等制备过程中各种环境因素和操作条件对淀粉酶、果胶酶、纤维素酶等多糖水解酶活性的影响规律；研究物料参数和反应条件对"红薯芽"催化水解红薯原料中淀粉、果胶、纤维素等多糖的影响规律；建立并优化相关工艺过程。预期研究成果可以拓宽对红薯内源非淀粉多糖水解酶的认识，为食品和发酵工业红薯原料预处理提供技术储备。

红薯是我国特色淀粉作物，年产量超过1亿吨，占世界总产量的80%。红薯茎块中果胶、纤维素等非淀粉多糖含量较高，开发针对性强的酶制剂，通过预处理降低培养基粘度，是红薯原料生产食品原料、大宗化学品等发酵过程急需解决的技术难题。本基金对红薯萌发过程中关键多糖水解酶的动态变化规律进行了系统研究，获得了淀粉酶、纤维素酶、果胶酶的诱导规律；优化并开发了“红薯芽”萌发、干燥、储存等制备过程工艺；应用“红薯芽”作为糖化酶对红薯粗原料进行水解预处理和同步糖化发酵乙醇；利用蛋白质工作站分离纯化获得了具有纤维素、果胶水解活性的蛋白组分，分子量分别是77KD、43KD，最适pH和温度分别是7.7、5.5和42 oC、40 oC，与文献报道的现有酶分子存在差异，初步判断为新酶或新酶结构。相关成果对丰富淀粉粗原料的多糖水解酶系统、开发高选择性、低生物污染风险的食品多糖酶制剂有重要意义。本研究技术的成熟化和系统化开发，将为红薯淀粉原料预处理生物化工过程提供新技术。