【摘要】：阿魏酸淀粉酯是一種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,使其備受關(guān)注。本文探索了在非水體系中,脂肪酶催化阿魏酸淀粉酯的合成。并通過UV、FTIR以及1HNMR對產(chǎn)物進(jìn)行檢測與分析。構(gòu)建非水反應(yīng)體系,利用2A分子篩平衡水活度,以取代度為指標(biāo)對底物、脂肪酶、有機(jī)溶劑進(jìn)行篩選,研究結(jié)果表明,在水活度0.01時(shí),以異辛烷為反應(yīng)介質(zhì),Novozym435脂肪酶為催化劑,催化阿魏酸乙酯與活化淀粉合成阿魏酸淀粉酯反應(yīng)易于發(fā)生,產(chǎn)物取代度最高,取代度為0.026。通過對反應(yīng)體系中底物摩爾比、酶添加量、反應(yīng)時(shí)間及反應(yīng)溫度的考察,確定了反應(yīng)體系的最佳工藝條件:在水活度0.01時(shí),底物摩爾比(阿魏酸乙酯:淀粉)為3:1、有機(jī)溶劑用量10mL、酶添加量為10%(以活化淀粉的質(zhì)量計(jì))、反應(yīng)時(shí)間為18h、反應(yīng)溫度為65℃,此時(shí),產(chǎn)物的取代度最高可達(dá)0.031。在確定最佳工藝的基礎(chǔ)上,對助溶劑的加入進(jìn)行了研究,考察了助溶劑的加入比例,結(jié)果表明助溶劑(二甲基亞砜、丙酮)與異辛烷體積比為3:7時(shí)產(chǎn)物取代度最大,取代度分別為0.0456、0.0408�？疾炝藟A金屬和過渡金屬離子對脂肪酶催化合成阿魏酸淀粉酯的影響。研究發(fā)現(xiàn),堿金屬離子和過渡金屬離子均表現(xiàn)出低濃度促進(jìn)高濃度抑制的現(xiàn)象,當(dāng)Mg2+、Ca2+、Ba2+等堿金屬離子濃度為10-4mol/L,Zn2+、Mn2+、Cu2+等過渡金屬離子濃度為10-6mol/L時(shí)酶活性最強(qiáng)。相對酶活最高為134.69%、173.07%。通過紫外、紅外、熒光光譜對酶結(jié)構(gòu)進(jìn)行檢測發(fā)現(xiàn),10-4mol/LMg2+可使Novozym435脂肪酶周圍環(huán)境的疏水性增強(qiáng),二級結(jié)構(gòu)趨向于柔性變化,增加了酶與底物的接觸機(jī)會(huì),導(dǎo)致酶促反應(yīng)活性增強(qiáng)。對阿魏酸淀粉酯的抗氧化性及物理特性進(jìn)行研究。結(jié)果表明,阿魏酸淀粉酯具有清除羥自由基、DPPH自由基、超氧陰離子的能力。同時(shí),與原淀粉相比阿魏酸淀粉酯的持水力、溶解度、透明度明顯增強(qiáng),黏度略微降低。并隨著取代度的增大而減小。
[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，

本文編號：2210330