非水体系脂肪酶催化阿魏酸淀粉酯合成
发布时间：2018-08-28 19:07
【摘要】：阿魏酸淀粉酯是一种新型的具有一定生理功能的改性淀粉,由于其既具有阿魏酸的生理功能又具有淀粉的理化特性,使其备受关注。本文探索了在非水体系中,脂肪酶催化阿魏酸淀粉酯的合成。并通过UV、FTIR以及1HNMR对产物进行检测与分析。构建非水反应体系,利用2A分子筛平衡水活度,以取代度为指标对底物、脂肪酶、有机溶剂进行筛选,研究结果表明,在水活度0.01时,以异辛烷为反应介质,Novozym435脂肪酶为催化剂,催化阿魏酸乙酯与活化淀粉合成阿魏酸淀粉酯反应易于发生,产物取代度最高,取代度为0.026。通过对反应体系中底物摩尔比、酶添加量、反应时间及反应温度的考察,确定了反应体系的最佳工艺条件:在水活度0.01时,底物摩尔比(阿魏酸乙酯:淀粉)为3:1、有机溶剂用量10mL、酶添加量为10%(以活化淀粉的质量计)、反应时间为18h、反应温度为65℃,此时,产物的取代度最高可达0.031。在确定最佳工艺的基础上,对助溶剂的加入进行了研究,考察了助溶剂的加入比例,结果表明助溶剂(二甲基亚砜、丙酮)与异辛烷体积比为3:7时产物取代度最大,取代度分别为0.0456、0.0408。考察了碱金属和过渡金属离子对脂肪酶催化合成阿魏酸淀粉酯的影响。研究发现,碱金属离子和过渡金属离子均表现出低浓度促进高浓度抑制的现象,当Mg2+、Ca2+、Ba2+等碱金属离子浓度为10-4mol/L,Zn2+、Mn2+、Cu2+等过渡金属离子浓度为10-6mol/L时酶活性最强。相对酶活最高为134.69%、173.07%。通过紫外、红外、荧光光谱对酶结构进行检测发现,10-4mol/LMg2+可使Novozym435脂肪酶周围环境的疏水性增强,二级结构趋向于柔性变化,增加了酶与底物的接触机会,导致酶促反应活性增强。对阿魏酸淀粉酯的抗氧化性及物理特性进行研究。结果表明,阿魏酸淀粉酯具有清除羟自由基、DPPH自由基、超氧阴离子的能力。同时,与原淀粉相比阿魏酸淀粉酯的持水力、溶解度、透明度明显增强,黏度略微降低。并随着取代度的增大而减小。
[Abstract]:Ferulic acid starch ester is a new type of modified starch with certain physiological function. It has not only the physiological function of ferulic acid but also the physicochemical properties of starch. In this paper, the synthesis of starch ferulic acid ester catalyzed by lipase in non-aqueous system was investigated. The products were detected and analyzed by UV,FTIR and 1HNMR. Non-aqueous reaction system was constructed. The equilibrium water activity of 2A molecular sieve was used to screen substrates, lipases and organic solvents. The results showed that isooctane was used as reaction medium and Novozym435 lipase as catalyst when water activity was 0.01. The catalytic reaction of ethyl ferulate with activated starch to synthesize starch ferulate ester was easy to occur, and the degree of substitution of the product was the highest (0.026). Through the investigation of the molar ratio of substrate, the amount of enzyme, the reaction time and the reaction temperature, the optimum reaction conditions were determined as follows: when the activity of water was 0.01, The molar ratio of substrate (ethyl ferulate: starch) was 3: 1, the amount of organic solvent was 10 mL, the amount of enzyme was 10% (based on the mass of activated starch), the reaction time was 18 h and the reaction temperature was 65 鈩，
本文编号：2210330
[Abstract]:Ferulic acid starch ester is a new type of modified starch with certain physiological function. It has not only the physiological function of ferulic acid but also the physicochemical properties of starch. In this paper, the synthesis of starch ferulic acid ester catalyzed by lipase in non-aqueous system was investigated. The products were detected and analyzed by UV,FTIR and 1HNMR. Non-aqueous reaction system was constructed. The equilibrium water activity of 2A molecular sieve was used to screen substrates, lipases and organic solvents. The results showed that isooctane was used as reaction medium and Novozym435 lipase as catalyst when water activity was 0.01. The catalytic reaction of ethyl ferulate with activated starch to synthesize starch ferulate ester was easy to occur, and the degree of substitution of the product was the highest (0.026). Through the investigation of the molar ratio of substrate, the amount of enzyme, the reaction time and the reaction temperature, the optimum reaction conditions were determined as follows: when the activity of water was 0.01, The molar ratio of substrate (ethyl ferulate: starch) was 3: 1, the amount of organic solvent was 10 mL, the amount of enzyme was 10% (based on the mass of activated starch), the reaction time was 18 h and the reaction temperature was 65 鈩，
本文编号：2210330
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