固定化脂肪酶催化合成癸二酸二(2-乙基己基)酯

在有机溶剂中,分别采用固定化脂肪酶Lipozyme TL IM,Lipozyme RM IM和Novozym 435催化癸二酸和2-乙基己醇合成癸二酸二(2-乙基己基)酯,考察了溶剂、反应温度、反应时间、酶量和底物比等对产率的影响.结果表明:反应温度40℃,癸二酸400 mg,2-乙基己醇0.96 mL(2-乙基己醇和癸二酸物质的量之比3),环己烷15 mL,在600 PLU固定化脂肪酶催化条件下反应24 h,Lipozyme TL IM催化产率可达96.94％,Lipozyme RM IM 催化产率可达96.23％,Novozym 435催化产率可达84.65％.在上述反应条件下,使用6次后,这3种固定化脂肪酶仍保持较高的催化活性.     

酶催化合成N-ε-油酰基赖氨酸及其结构表征

以赖氨酸和油酸为原料,在微水有机溶剂中,脂肪酶Lipozyme TL IM的催化下,合成了N-ε-油酰基赖氨酸。通过正交实验考察了各因素对赖氨酸转化率的影响,得出较佳工艺条件:在正辛烷中,催化剂Lipozyme TLIM加入量为反应体系总质量的2%,除水剂5A分子筛的加入量为反应体系总质量的5%,投料比n(赖氨酸)∶n(油酸)=1∶5,反应温度70℃,反应时间72 h,赖氨酸的转化率达57.5%。用IR、元素分析、13CNMR、1HNMR等对目的产物的结构进行了表征。     

酶促合成肝靶向脂质材料的研究

目的:在有机相中酶法构建一种新型去唾液酸糖蛋白(asialoglycoprotein Receptor,ASGPR)介导的肝靶向性配体脂质材料[(5-cholesten-3b-yl)(acetyl-2-deoxy-d-galactopyranose-6-o)sebacate,CHS-SE-NGal],并对其合成工艺进行优化。方法:通过质谱(ESI-MS)和核磁共振(1H-NMR、13C-NMR)对产物进行结构确证,并对酶的种类、酶量、底物摩尔比、反应介质、反应温度、反应时间进行单因素考察。结果:丙酮作为反应介质、Lipozyme TL IM脂肪酶为催化剂、N-乙酰-D-半乳糖胺(N-Gal)与胆固醇癸二酸单烯酯[(5-cholesten-3β-yl)vinyl sebacicacid,CHS-SE]摩尔比为1:2、反应温度为45℃、反应时间为12 h为最优条件,产率可达85%以上。结论:酶法合成CHS-SE-NGal高效、操作方便、可靠。     

脂肪酶催化玉米油合成脂肪酸乙酯工艺研究

为研制食药两用的功能性原料亚油酸乙酯,以玉米油和乙醇为原料,经固定化脂肪酶催化合成脂肪酸乙酯。通过单因素试验和响应面分析法(RSM)研究醇油摩尔比、脂肪酶用量、反应温度、反应时间对玉米油脂肪酸乙酯合成的影响。研究结果表明,玉米油脂肪酸乙酯合成的最佳工艺条件为醇油摩尔比为4∶1,脂肪酶质量分数为30.82%,反应温度为50.39℃,反应时间为24.15 h,在此工艺条件下脂肪酸乙酯转化率为90.20%。     

响应面法优化脂肪酶催化废油脂合成生物柴油工艺的研究

利用响应面法对酶催化废油合成生物柴油复杂的反应条件进行优化研究.采用6因素5水平和中心组分旋转设计法研究了反应温度、酶用量、流加次数、有机溶剂用量、底物摩尔比和水含量诸因素共同作用对反应转化率的影响.优化后的反应条件为反应温度34℃、酶用量30%(相对于油的质量分数)、流加次数4次、有机溶剂用量和水含量皆为0、底物醇油摩尔比为2,在该反应条件下转化率可达94.6%.     

酶催化酸性油连续法制备脂肪酸乙酯

采用从嗜热真菌(Thermomyces lanuginosus)中提取的Lipozyme TL IM(Novozymes,Seoul, Korea)作为固定化脂肪酶,考察了其催化酸性油与乙醇反应制备脂肪酸乙酯的合成工艺。其中原料酸性油主要是由米糠油精制过程中产生的副产物(皂脚)的酸化获得。研究了水含量、反应温度和物料比对该工艺的影响,并对固定化脂肪酶重复利用过程中Lipozyme TL IM的相对活性进行了评价。研究结果表明:反应物中水含量对酯的收率影响很大,最佳含水量为4%;最佳反应温度是20℃,酸性油/乙醇的最佳物料比为1:4。在最佳工艺条件下,最大收率为92%,产物组成为92%脂肪酸乙酯、3%脂肪酸和5%酰基甘油。通过间歇性的乙醇洗涤工艺可将反应生成的甘油去除,并且脂肪酶在循环使用了27次后依然可以保持82%以上的相对活性。以平均4 h滞留时间计算,Lipozyme TL IM在不进行乙醇洗涤和进行乙醇洗涤两种工艺中的半衰期分别为39和45次循环。     

固定酶催化合成正辛基葡萄糖苷工艺研究

为研制绿色环保型生物表面活性剂烷基糖苷,通过单因素试验、正交多项式设计试验和极差分析对固定酶催化合成正辛基葡萄糖苷工艺参数进行优化,结果表明:反应温度、反应时间、醇糖比、剂醇比和加水量对葡萄糖转化率影响较大;葡萄糖转化率随反应温度的升高、反应时间的延长、醇糖比、剂醇比和加水量的增大而增大;影响合成反应中葡萄糖转化率的主次因素依次为醇糖比(正辛醇与葡萄糖质量比)、剂糖比(固定酶与葡萄糖质量比)、加水量、反应时间、反应温度;合成最佳工艺参数为反应温度50℃,反应时间72 h,醇糖比11∶1,剂糖比13∶1、加水量15%(质量分数),葡萄糖转化率最大为97.13%。     

高纯度单月桂酸甘油酯的酶催化合成工艺

采用脂肪酶Novozyme 435催化月桂酸甲酯与甘油进行酯交换反应制备单月桂酸甘油酯。以反应体系中单月桂酸甘油酯的质量分数为考察指标,通过单因素实验和正交实验对酶催化合成工艺进行优化,得到最佳的工艺条件为：底物摩尔比1:5,底物质量分数20%,反应温度55 ℃,酶添加量为7%,初始含水量为20%,转速为100 r/min,反应时间1 h,在该条件下,体系中单月桂酸甘油酯的质量分数为71.86%。经提纯后终产物中单月桂酸甘油酯的质量分数高于95%,最高可达98.76%,而双月桂酸甘油酯的质量分数低于5%。在最佳工艺条件下,酶重复使用6次,单月桂酸甘油酯的质量分数从71.75%降至68.36%,其催化性能无显著降低。     

高纯度单月桂酸甘油酯的酶催化合成

采用脂肪酶Novozyme 435催化月桂酸甲酯与甘油进行酯交换反应制备单月桂酸甘油酯。以反应体系中单月桂酸甘油酯的质量分数为考察指标,通过单因素实验和正交实验对酶催化合成工艺进行优化,得到最佳的工艺条件为:底物摩尔比n(月桂酸甲酯)∶n(甘油)=1∶5,底物质量分数为20%(即月桂酸甲酯与叔丁醇的质量百分数,下同),反应温度为55℃,酶添加量为7%(即酶与月桂酸甲酯的质量百分数,下同),初始含水量为20%(以月桂酸甲酯质量计,下同),转速为100 r/min,反应时间为1 h,在该条件下,体系中单月桂酸甘油酯的质量分数为71.86%。经提纯后终产物中单月桂酸甘油酯的质量分数高于95%,最高可达98.76%,而双月桂酸甘油酯的质量分数低于5%。酶重复使用6次,单月桂酸甘油酯的质量分数从71.75%降至68.36%,其催化性能无显著降低。     

植物甾醇酯的酶法合成

以油酸和植物甾醇为反应底物,利用脂肪酶催化合成植物甾醇油酸酯。对脂肪酶和反应介质进行了筛选,同时对影响合成植物甾醇油酸酯反应的因素进行了探究,考察了底物摩尔比(油酸甾醇比)、酶添加量(脂肪酶质量/底物总质量)、反应温度及反应时间对酯化反应的影响。在单因素的基础上,经酯化率响应曲面实验优化反应条件,确定最佳反应条件:催化酯化反应的酶为柱状假丝酵母脂肪酶(CRL,Candida rugosa lipase),反应介质为正己烷,底物摩尔比为3∶1,酶添加量为7.2%,反应温度为45.3℃,反应时间为25.3h,验证试验酯化率可达72.95%。     

Lipase-catalyzed glycerolysis of olive oil in organic solvent medium: Optimization using response surface methodology

Enzymatic glycerolysis of olive oil for mono- (MG) and diglycerides (DG) synthesis was investigated. Several pure organic solvents and co-solvent mixtures were screened in a batch reaction system. The yields of MG and DG in co-solvent mixtures exceeded those of the corresponding pure organic solvents. Batch reaction conditions of the glycerolysis reaction, the lipase amount, the glycerol to oil molar ratio, the reaction time, and temperature, were studied. In these systems, the high content of reaction products, especially MG (55.8 wt%) and DG (16.4wt%) was achieved at 40 °C temperature and 0.025 g of lipase with relatively low glycerol to oil molar ratio (2: 1) within 4 h of reaction time in isopropanol/tert-butanol (1: 3) solvent mixture. Glycerolysis reaction was optimized with the assistance of response surface methodology (RSM). Optimal condition for reaction conversion was recommended as lipase amount 0.025 g, glycerol to oil molar ratio 2: 1, reaction time 4 h and temperature 40 °C.     

无溶剂体系中酶催化合成共轭亚油酸甘油酯

采用直接酯化法,以共轭亚油酸(简称CLA)和甘油为原料,用脂肪酶Novozym 435催化合成共轭亚油酸甘油酯。结果表明:n(甘油)/n(CLA)=5,酶添加量为体系总质量的4%,65℃反应6 h后,共轭亚油酸的转化率为98.18%。所得共轭亚油酸甘油酯为淡黄色油状透明液体,酸价低于3,Novozym 435的操作半衰期为30 h。     

Five-factor response surface optimization of the enzymatic synthesis of citronellyl butyrate by lipase IM77 from Mucor miehei

Response surface methodology (RSM) and a five-level-five-factor central composite rotatable design (CCRD) were used to evaluate the effects of synthetic variables, such as reaction time (3 to 27 h), temperature (25 to 65 °C), enzyme amount (10 to 50%), substrate molar ratio of citronellol to butyric acid (1∶1 to 1∶3), and added water amount (0 to 20%) on molar percent yield of citronellyl butyrate by direct esterification, using lipase IM77 from Mucor miehei. Reaction time and temperature were the most important variables. Substrate molar ratio had no effect on percent molar conversion. Based on contour plots, optimal synthetic conditions were these: reaction time 24 h, temperature 60°C, enzyme amount 20%, substrate molar ratio 1∶1.5, and added water 0%. The predicted molar conversion value was 100%. An actual experimental value of 98% molar conversion was obtained.     

Enzymatic synthesis of monoacylglycerol citrate optimized by response surface methodology

The ability of immobilized lipase B from Candida antarctica (Novozym 435) to catalyze the direct esterification of citric acid (CA) and monoglyceride (MG) for citrate esters of monoacylglycerols (CITREM) preparation was investigated. The effects of substrate concentration, molecular‐sieve amount, substrate molar ratio, reaction temperature, time, and enzyme load on the conversion of CA in the reaction were investigated. Enzyme screening and the effect of solvent on the esterification were also investigated. RSM was used to optimize the effects of the reaction temperature (45–55°C), the enzyme load (6–10%; relative to the weight of total substrates), and the reaction time (24–48 h) on the conversion of CA. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of CA conversion. The optimum preparation conditions were as follows: CA concentration 0.12 mol/L, molecular‐sieve 120 g/L, molar ratio of MG/CA 2:1, temperature 54.18°C, enzyme load 9.0% (relative to the weight of total substrates), and reaction time 47.5 h. Under the suggested conditions, the conversion of CA was 77.4%. Repeated reaction tests indicated that Novozym 435 could be used eight times under the optimum conditions with 92% of its original catalytic activity still retained.     

Production of geranyl propionate by enzymatic esterification of geraniol and propionic acid in solvent‐free system

Background: This work reports the optimization of geranyl propionate production by esterification of geraniol and propionic acid in a solvent‐free system using a commercial lipase as catalyst. For this purpose, a sequential strategy was performed applying two experimental designs. Results: The operating conditions that optimized geranyl propionate production were determined to be 40 °C, geraniol to propionic acid molar ratio of 3:1, 150 rpm and 10 wt% of enzyme, with a resulting reaction conversion of about 93%. After determining the optimum reaction parameters, a kinetic study was carried out evaluating the influence of substrates molar ratio, enzyme concentration and temperature on reaction conversion. Results obtained in this step allow one to conclude that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (5 wt%), temperature of 40 °C and substrates molar ratio of 1:1 afforded nearly complete reaction conversion after 30 min of reaction. Conclusion: New experimental data on enzymatic esterification of geraniol and propionic acid for geranyl propionate production are reported in this work, showing a promising perspective of the technique to overcome the well‐known drawbacks of the chemical‐catalyzed route. Copyright © 2010 Society of Chemical Industry     

Lipase‐catalyzed production of medium‐chain triacylglycerols from palm kernel oil distillate: Optimization using response surface methodology

Optimization of lipase‐catalyzed esterification for the production of medium‐chain triacylglycerols (MCT) from palm kernel oil distillate and glycerol was carried out in order to determine the factors that have significant effects on the reaction system and MCT yield. Novozyme 435 from Candida antarctica lipase was found to have the highest activity at 52.87 ± 0.03 U/g. This lipase also produced the highest MCT yield, which is 56.67%. The effect of different variables on MCT synthesis was studied with a two‐level five‐factor fractional factorial design. The various variables include (1) reaction temperature, (2) enzyme load, (3) molecular sieves concentration, (4) reaction time and (5) molar substrate ratio. Reaction temperature, reaction time and molar substrate ratio strongly affect MCT synthesis (p <0.05). However, enzyme load and molecular sieve concentration did not have a significant (p >0.05) influence on MCT yield. Therefore, the significant variables such as reaction temperature, reaction time and molar substrate ratio were further optimized through central composite rotatable design (CCRD). Comparisons between predicted and experimental values from the CCRD optimization procedures revealed good correlation, implying that the quadric response model satisfactorily expressed the percentage yield of MCT in the lipase‐catalyzed esterification. The optimum MCT yield is 73.3% by using 2 wt‐% enzyme dosage, a molecular sieves concentration of 1 wt‐%, a reaction temperature of 90 °C, a reaction time of 10 h and a molar substrate ratio of 4 : 1 (medium‐chain fatty acid/glycerol). Experiments to confirm the predicted results using the optimal parameters were conducted and an MCT yield of 70.21 ± 0.18% (n = 3) was obtained.     

Optimization of Enzymatic Synthesis of Cetyl 2-Ethylhexanoate by Novozym<Superscript>®</Superscript> 435

Waxes are esters obtained from long-chain fatty acids and long-chain alcohols which are biodegradable, biocompatible and nontoxic. Seafowl feather oil is a natural wax ester that exists on seafowl feathers. Cetyl 2-ethylhexanoate is the major ingredient of seafowl feather oil. Cetyl 2-ethylhexanoate is widely used in cosmetics as a base oil because of its lubricity, moisture retention and non-toxic properties. An optimal production of cetyl 2-ethylhexanoate by direct esterification of cetyl alcohol with 2-ethylhexanoic acid was developed using an immobilized lipase (Novozym^® 435) as a catalyst in n-hexane. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of reaction time, reaction temperature, substrate molar ratio, and enzyme amount on the yield of cetyl 2-ethylhexanoate. The results show that reaction time, reaction temperature, substrate molar ratio, and enzyme amount have significant effects on the yield of the esterification reaction. On the basis of ridge-max analysis, the optimum conditions were as follows: a reaction time of 2.65 days, a reaction temperature of 56.18 °C, a substrate molar ratio of 2.55:1, and an enzyme amount of 251.39%. The predicted and experimental values of molar conversion were 91.95 and 89.75 ± 1.06%, respectively.     

Lipase-catalyzed synthesis of fattythioic acids from palm oil

The present work focuses on the synthesis of fattythioic acids (FTAs) by a one-step lipase catalyzed reaction of palm oil with carbonothioic S,S-acid using Lipozyme. The product was characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The effects of various reaction parameters such as reaction time, temperature, amount of enzyme, molar ratio of substrates, and various organic solvents of the reaction system were investigated. The optimum conditions to produce FTAs were respectively, incubation time, 20 h, temperature, 40°C, amount of enzyme, 0.05 g and molar ratio of carbonothioic S,S-acid to palm oil, 5.0:1.0. Hexane was the best solvent for this reaction. The conversion of the products at optimum conditions was around 91%.     

甘油二酯的酶法合成工艺研究

以固定化脂肪酶为催化剂,研究无溶剂体系下甘油和辛酸直接酯化合成甘油二酯工艺。在选用的3种脂肪酶中,发现Novozym e 435催化效果最好。以Novozym e 435为催化剂,考察了底物摩尔比、温度、反应加酶量以及脱水方式等因素对辛酸转化率和甘油二酯含量的影响,并通过响应面法优化了工艺参数,获得酶法合成甘油二酯的最优工艺条件:酸油比1.99∶1,反应温度51.5℃,加酶量3.05%,反应时间6.29 h。在最优条件下,甘油二酯的含量达到71.9%。     

Synthesis of CLA‐enriched TAG by Candida antarctica lipase under vacuum

Conjugated linoleic acid (CLA)‐enriched triacylglycerol (TAG) of 90 wt% was successfully synthesized in 10 h by direct esterification of glycerol and CLA using an immobilized lipase from Candida antarctica under vacuum. The best operating conditions for the synthesis of TAG were investigated according to the three parameters of temperature, enzyme loading, and vacuum. The synthesis of TAG increased with increasing temperature but it did not significantly change above 60°C (p>0.05). The increase of enzyme loading lead to an enhanced conversion of TAG, but enzyme loading of more than 10% (based on the total weight of the substrates) was not effective. Moreover, when vacuum increased, the conversion of TAG increased, but the conversion rate decreased when the vacuum level was too high. The best combination of temperature, enzyme loading, and vacuum level were 60°C, 10% of the total weight of the substrates, and 0.4 kPa, respectively. During the initial 6 h of reaction, Candida antarctica lipase had more selectivity for 10t,12c‐CLA than 9c,11t‐CLA onto the glycerol backbone, and a preference for the incorporation at the sn‐1,3 positions of glycerol rather than at the sn‐2 position.