【作者】 胡华宇；

【导师】 黄祖强；

【作者基本信息】 广西大学 ， 化学工艺， 2007， 硕士

【摘要】 淀粉是一种多晶高聚物，其颗粒中一部分分子排列成疏松的非晶区(无定形区)，另一部分分子则排列成高度有序的结晶区。由于淀粉这种独特的分子结构特点，水及反应物等不易触及结晶区内的分子，导致淀粉的糊化温度高、糊粘度过大、流动性差、化学反应活性低，淀粉的这种结构特点使淀粉酶无法直接作用于原淀粉。以淀粉为原料，无论是淀粉糖系列产品还是酒精、乳酸等的生产都必须先加热淀粉乳使淀粉颗粒吸水膨胀、糊化，破坏其结晶结构，然后用酸或α-淀粉酶对糊化淀粉进行催化水解到一定的糊精和低聚糖程度，粘度大为降低，流动性增强，最后再糖化。因此，研究如何通过新技术手段的运用来强化淀粉的液化水解，提高水解效率，实现无蒸煮液化、糖化工艺，降低能耗，已成为一个重要的研究方向。本文采用自制搅拌磨对淀粉进行机械活化，做了如下研究：(1)采用不同活化时间淀粉为原料、α-淀粉酶为液化试剂，以液化水解产物的葡萄糖值(Dextrose Equivalent，DE)为评价指标，通过研究机械活化时间、糊化温度、反应时间、反应温度、淀粉糊浓度、淀粉酶用量、pH值等因素对DE值的影响规律，分析讨论机械活化对淀粉酶解反应活性的影响。研究结果表明，经机械活化处理后的淀粉酶解反应活性明显提高，酶解速度加快，酶解时间大大缩短。这主要是机械活化能有效将淀粉的α-1，6葡萄糖苷键破坏，降低粘度，提高冷水溶解度，从而实现从内部强化淀粉的液化过程。(2)用α-淀粉酶和糖化酶协同作用木薯、玉米淀粉，探讨双酶作用下淀粉的水解情况。结果表明，双酶作用下淀粉的水解程度比单酶单独使用的作用大，双酶处理下机械活化淀粉甚至可不经糊化直接与酶作用，这对生产实际具有重要的指导意义。(3)用高效液相色谱(High Performance Liquid Chromatography，HPLC)检测液化水解产物组成，经糊化处理的木薯原淀粉和活化60min木薯淀粉、未经糊化处理的活化60min木薯淀粉还原糖(葡萄糖和麦芽糖)含量依次为6.06％、12.31％、11.46％，经糊化处理的玉米原淀粉和活化60min玉米淀粉、未经糊化处理的活化60min玉米淀粉还原糖含量依次为4.12％、8.14％、7.66％，结果表明活化淀粉的还原糖含量较原淀粉高。双酶作用下水解产物的主成分为葡萄糖，经糊化处理的木薯原淀粉和活化60min木薯淀粉、未经糊化处理的活化60min木薯淀粉还原糖含量依次为16.93％、30.47％、27.71％，经糊化处理的玉米原淀粉和活化60min玉米淀粉、未经糊化处理的活化60min玉米淀粉还原糖含量依次为15.84％、28.02％、26.12％，证明机械活化能有效提高淀粉反应活性，活化淀粉可不经糊化达到较好的酶解效果。更多还原

【Abstract】 Starch is a complex high-polymer, consisting of loose amorphous regions and interspersed ordered crystalline regions. Water and chemical reagents could not easily enter into the inner crystalline regions because of this unique structure, which results in a high gelatinizing temperature, large viscosity, poor fluidity and poor chemical reactivity of starch. For example, amylase could not react with native starch directly. Therefore, in the traditional fabricating technology of starch sugar, alcohol and lactic acid using starch as the raw material, it is usually necessary to destroy the crystalline structure of starch first. The destroyed structure could be realized by heating the water-absorbed starch, which leads to the expansion and gelatinization of the starch structure. Followed by a hydrolysis process assisted with the catalyst of acid orα-amylase, a kind of dextrin with low viscosity and good fluidity is obtained. Finally the dextrin is saccharified to produce the product. Therefore it is of great interest and significance to explore novel method to promote the hydrolysis efficiency of starch and develop a liquefaction and saccharification processing without steam to reduce energy consumption. In this thesis, cassava and maize starch were first mechanical activated by a high-energy stirring-type ball mill.The main researchful contents as follows:(1) the activated starch with different milling time was used as the starting material. Usingα-amylase as the liquefaction reagent, dextrose equivalent (DE) of the hydrolysis product as an evaluating parameter, the influences of activation time, gelatinization temperature, reaction time, reaction temperature, starch concentration, amylase dosage and PH value on the DE were investigated in detail. It was found that the mechanical activation could obviously enhance the anzymolysis of the starch. That is because the mechanical activation could efficiently destroy the glucoside bond ofα-1,6 glucose and therefore decrease the viscosity, enhance the cold-water solubility and finally improve the liquefaction of the starch. (2) The effects of the combinedα-amylase and saccharification enzymes on the hydrolysis of cassava and maize starch were also studied. The results indicate that the starch hydrolysis degree in the case of double enzymes used is larger than that in the case of one enzyme used. Furthermore, in the case of double enzymes used, the activated starch could react directly with enzyme without gelatinization, which is of great practically significance.(3) High Performance Liquid Chromatography (HPLC) was employed to analyze the product composition of the starch liquefaction hydrolysis. The results show that the contents of reducing sugar (including glucose and maltose) in the gelatinized native cassava starch, activated cassava starch (with activation time of 1.0h) with and without gelatinization are 6.06%, 12.31% and 11.46%, respectively. The contents of reducing sugar in the gelatinized native maize starch, activated maize starch (with activation time of 1.0h) with and without gelatinization are 4.12%, 8.14% and 7.66%, respectively. It can be seen that the reducing sugar content in the activated starch is higher than that in the native starch. In the case of double enzymes used, the hydrolysis product is mainly composed of glucose with a small amount of maltose. The contents of reducing sugar in the gelatinized native cassava starch, activated cassava starch (with activation time of 1.0h) with and without gelatinization are 16.93%, 30.47% and 27.71%, respectively. The contents of reducing sugar in the gelatinized native maize starch, activated maize starch (with activation time of 1.0h) with and without gelatinization are 15.84%, 28.02% and 26.12%, respectively. These results clearly indicate that the mechanical activation processing could really enhance the enzymolysis activity and very good enzymolysis effect could be obtained in the activated starch even without gelatinization.更多还原