【作者】 袁建微；

【导师】 黄祖强；

【作者基本信息】 广西大学 ， 化学工艺， 2008， 硕士

【摘要】 麦芽糖浆甜度低、抗结晶性好、稳定性高,广泛应用于食品工业、化学工业、保健产品及医药行业中,是淀粉糖工业的重要产品之一。然而淀粉具有半结晶的颗粒结构,内部主要是非晶区域,外层主要为结晶区域且非常牢固,淀粉颗粒的结晶性结构对酶作用的抵抗力强,从而导致其反应效率低。因此,以淀粉为原料,生产麦芽糖浆时必须进行加热淀粉乳使淀粉颗粒吸水膨胀、糊化,以破坏其结晶结构,再进行水解糖化。本文采用自制搅拌球磨机对木薯、玉米淀粉进行机械活化,以不同活化时间的淀粉为原料,以真菌α-淀粉酶为糖化试剂,分别研究了机械活化淀粉直接糖化效果、糖化动力学及直接糖化生产麦芽糖浆工艺,实验结果表明:（1）在同样反应条件下,木薯原淀粉及其活化60 min淀粉糖化DE值分别是46.64%、64.41%;玉米原淀粉及其活化60 min淀粉糖化DE值分别是43.81%、61.33%。由此可见,淀粉经机械活化后由于其紧密的颗粒表面受到破坏,分子链发生断裂,粘度下降,流动性增强,淀粉酶的扩散阻力下降,淀粉的酶解反应活性明显提高。其它的反应条件如糊化温度、反应时间、底物浓度、淀粉酶用量等对淀粉的酶解反应也有较大的影响,但它们的影响规律受到活化时间的制约,活化时间越长,酶解反应对它们的依赖性越低。（2）动力学研究表明,真菌α-淀粉酶对活化木薯、玉米淀粉的作用与原淀粉同样遵循Michaelis-Menten方程,其中活化60 min木薯及玉米淀粉K_m分别为9.086 mg·mL^-1,1.335 mg·mL^-1,V_max分别为0.761 mg·mL^-1·min^-1,0.171 mg·mL^-1·min^-1;木薯及玉米原淀粉K_m分别为1.651 mg·mL^-1,0.639mg·mL^-1,V_max分别为0.145 mg·mL^-1·min^-1,0.086 mg·mL^-1·min^-1,可见活化淀粉的反应速率明显比原淀粉大。证明了机械活化预处理对淀粉结晶结构具有破坏作用,提高了淀粉的酶解能力,从而起到强化淀粉酶解的作用。（3）麦芽糖浆工艺研究表明,活化30 min的木薯淀粉和活化60 min玉米淀粉均不糊化,在制备条件为反应温度50℃,底物浓度30 mg·mL^-1,酶用量4 U,pH值为5.5,反应15 h时,糖化产物中麦芽糖的含量分别为49.55%,47.77%;而在相同条件下,80℃糊化15min的木薯及玉米原淀粉糖化产物中麦芽糖的含量分别仅为37.34%,41.59%。由此可见,机械活化淀粉不经糊化直接糖化制备麦芽糖浆即可达到较好效果。更多还原

【Abstract】 Maltose syrup has been widely applied in food industry, chemical industry, hygienical products and medical industry because of its low sweetness, good crystalline-resistance and high stability. It is one of the important products in starch sugar industry. However, starch particle possesses a semi-crystalline structure that consists of a loose amorphous region in the inner part and a firm crystalline region in the outer part. Enzymes could not easily enter into the inner regions of starch particles, resulting in a low reactive efficiency. Therefore, for the traditional producing technology of maltose syrup using starch as raw material, it is necessary to expand and gelatinize starch particles by heating starch milk and destroy crystalline structure of starch before hydrolyzation and saccharification.In this thesis, cassava and maize starch were mechanically activated with a customized stirring-type ball mill. The activated starches with different milling time were used as raw materials and fungal-a-amylase was used as the saccharification reagent. Then the effects of the mechanical activation on the saccharification, saccharifying kinetics and preparation technology of maltose syrups were investigated. The experiment results showed:（1） For cassava starch, the DE values of saccharification are 46.64% and 64.41% for non-activated starch and activated starch （with an activation time of 60 min）, respectively. For maize starch, the DE values of saccharification are 43.81% and 61.33% for non-activated starch and activated starch （with an activation time of 60 min）, respectively. It can be seen that the enzymolysis reactivity of starch was dramatically enhanced after the processing of mechanical activation. The reason is that the compact outer crystalline structure of starch particle was destroyed through the treatment of mechanical activation, which caused the breakage of starch molecular chain, the reduce of viscosity and finally the decrease of diffusion resistance of amylase. Other factors, such as gelatinization temperature, reaction time, substrate concentration and fungal-α-amylase amount, also have influences on the enzymolysis reaction. However, their effects are greatly related with the activation time. But the dependence weakens with the increase of activation time.（2） The kinetics study showed that action mechanism of fungal-α-amylase on both the saccharification of mechanically activated starch and the saccharification of non-activated starch follows the so-called Michaelis-Menten equation. For non-activated cassava starch, the K_m and V_max are 1.651 mg·mL^-1 and 0.145 mg·mL^-1·min^-1, respectively; while for the activated one, the K_m and V_max are 9.086 mg·mL^-1 and 0.761 mg·mL^-1·min^-1, respectively. For non-activated maize starch, the K_m and V_maxare 0.639 mg-mL^-1 and 0.086 mg·mL^-1·min^-1, respectively; while for the activated one, they are 1.335 mg-mL^-1 and 0.171 mg·mL^-1·min^-1, respectively. It can be seen that the reaction rate of activated starch is larger than that of non-activated starch. The results indicated that the mechanical activation processing could destroy the crystal structure and enhance the enzymolysis reactivity of starch obviously.（3） The study on preparation technology of maltose syrup showed that when the reaction temperature was 50℃, substrate concentration was 30 mg-mL^-1, fungal-a-amylase amount was 4U, pH was 5.5 and the reaction time was 15 hours, the content of maltose in the produced syrup are 49.55% and 47.77% in the case of raw material of activated cassava starch （with an activation time of 30 min） and activated maize starch （with an activation time 60min）, respectively. Under the same reaction conditions, however, the content of maltose in the produced syrup are only 37.34% and 41.59% in the case of raw material of non-activated cassava starch and non-activated maize starch, respectively. The result clearly indicated that the mechanical activation processing could favor the preparation of maltose syrup from starch even without gelatinization.更多还原