杂醇油酶法制备天然等同酯香料的研究

研究了无溶剂体系中杂醇油酶法转化制备天然等同酯香料的影响因素,筛选适宜脂肪酶,优化工艺条件,研究超声处理对酶法制备酯香料的作用.结果表明:在无溶剂体系中固定化脂肪酶Novozym 435 FG的酯化活力高且易回收,乙酸异戊酯产率达到92.62％;除水剂分子筛的加入促进了酯化反应,乙酸加入次数和间隔时间、反应温度和反应时间、摇床转速及超声处理对酯香料的产率均有影响.酶法制备酯香料的较优条件为1.5 mL乙酸分6次加入、间隔时间3 h、反应时间36 h、分子筛添加量2 g、杂醇油3 mL、脂肪酶加入量70 mg、温度45℃、转速140 r/min,其乙酸异戊酯、乙酸异丁酯、乙酸正丙酯的产率分别达到(89.2±0.7)％、(89.3±0.6)％、(76.8±0.9)％,与正己烷反应体系的酯产率接近.在超声频率50 Hz、单位面积超声功率0.5 W/cm2处理6 h时酯香料产率达85％,说明适当超声处理可加速反应进程,显著缩短反应时间,但超声处理的酯香料最终产量和产率未见增加,且长时间超声空化作用造成体系微环境改变,降低了固定化酶稳定性和使用次数.     

非水相介质酶法转化制备乙酸3- 甲硫基丙醇酯工艺

研究脂肪酶催化合成天然乙酸3-甲硫基丙醇酯的关键因素及条件。结果表明：固定化脂肪酶Novozym 435是无溶剂体系和正己烷体系中最佳催化剂,加酶量、分子筛用量、乙酸加入次数、反应温度、反应时间等因素对乙酸3-甲硫基丙醇酯合成有重要影响。在无溶剂体系体系,加有1.06g 3-甲硫基丙醇、0.6g乙酸的反应中正交试验设计优化的条件为：加酶量50mg、分子筛加入量2g、反应温度42℃、反应总时间30h,乙酸分3次加入,间隔时间为2h,摇床转速为150r/min,乙酸3-甲硫基丙醇酯产率达42.4%。     

非水相脂肪酶催化合成L-抗坏血酸硬脂酸酯

研究了非水介质中Novozym435脂肪酶催化合成L-抗坏血酸硬脂酸酯(L-AS)。脂肪酶用量固定为L-抗坏血酸质量的20%,底物L-抗坏血酸与硬脂酸的摩尔比限定为1:2,对影响脂肪酶催化的因素如溶剂、温度、溶剂量、反应时间、分子筛用量和摇床转速进行了研究。优化后的反应条件:在30mL叔丁醇中加入6.82mmolL-抗坏血酸,13.64mmol硬脂酸,0.24g脂肪酶和3.0g4A分子筛,摇床转速150r/min,反应在55℃水浴中进行48h。通过分离提纯,产品采用红外及质谱检测后确定为L-抗坏血酸硬脂酸酯,产率最高时达64.7%。脂肪酶重复使用5次,最低产率为61%。     

离子液体催化合成香料乙酸异戊酯

冰醋酸和异戊醇在离子液体[(C2H5)3NH][HSO4]的催化作用下,合成香料乙酸异戊酯.通过正交试验优化反应条件,考察反应时间、反应温度、醇酸摩尔比、离子液体用量4个因素对产率的影响.优化的最佳反应条件为:冰醋酸0.02mol,反应时间4h,反应温度90℃,醇酸摩尔比0.9∶1,离子液体用量2g,产率达到78.1％.离子液体可循环使用4次,催化活性基本不变.     

正己烷反应体系中酶法转化乙酸3-甲硫基丙醇酯的工艺条件

研究了脂肪酶催化合成天然香料乙酸3-甲硫基丙醇酯（EMTP）的关键因素及条件。以发酵3-甲硫基丙醇、己酸为主要原料酶法合成EMTP的反应中,固定化Novozym435脂肪酶为最佳催化剂,正己烷作为溶剂有利于提高酶活力;在正己烷反应体系中,Novozym435用量、分子筛吸水剂用量、乙酸加入次数、反应温度、反应时间等因素对EMTP合成有重要的影响,添加Novozyme435 50mg、分子筛2g、反应温度40℃、乙酸分3次加入、摇瓶速率100～150r／min,反30h为较佳的反应条件,其EMTP产量为6．5mg／mL.     

乙酸甲酯体系酶法崔化煎炸废油制备生物柴油

煎炸废油经过脱胶、脱酸、脱色处理后,以其为原料和乙酸甲酯在固定化脂肪酶的催化下反应制备生物柴油。考察反应条件对酯交换反应的影响,得到的最佳条件为：煎炸废油2．0g、固定化脂肪酶Novozym435的用量为油重的9％、有机溶剂叔丁醇2．0mL、乙酸甲酯与煎炸废油摩尔比9：1、有机碱三羟甲基氨基甲烷的用量为油重的15％、反应时间12h、反应温度60℃、摇床转速为150r／min。在此条件下生物柴油的得率为80．73％。     

非水介质中脂肪酶催化合成正戊酸异戊酯的研究

德氏根霉菌(Rhizopusdelemar) 经固态发酵生产脂肪酶,以此酶为催化剂,在非水介质中合成了正戊酸异戊酯。研究了反应温度、溶剂、底物浓度、底物摩尔比、吸水剂用量等因素对酯化反应的影响,确定了正戊酸异戊酯的最佳合成条件为:反应温度为5 0℃,异辛烷为反应介质,底物浓度为0 15mol/L ,酸醇摩尔比为1∶1 4。在反应体系中需加入0 2 5 g/mL的5 分子筛,以吸收酯化反应生成的水。在优化的条件下,反应6h后,酯合成转化率达98%。     

酶催化合成大豆甾醇油酸酯的工艺研究

以大豆甾醇和油酸为原料,在酶的催化下合成大豆甾醇油酸酯,采用高效液相色谱对产物进行定性定量分析,通过单因素实验考察催化剂脂肪酶的种类和用量、醇酸摩尔比、反应温度和反应时间等对大豆甾醇油酸酯产率的影响,并通过正交实验优化大豆甾醇油酸酯的合成工艺条件。采用红外光谱对产物进行了表征。结果表明:大豆甾醇油酸酯的最佳合成工艺条件为催化剂N435脂肪酶用量6%(以大豆甾醇和油酸的总质量计)、醇酸摩尔比1∶1、反应温度50℃、反应时间30 h、异辛烷用量10 mL(大豆甾醇为1 mmol时),在最佳条件下大豆甾醇油酸酯产率为86. 51%;红外表征说明合成的产物为大豆甾醇油酸酯。     

乙酸甲酯体系酶法催化煎炸废油制备生物柴油

煎炸废油经过脱胶、脱酸、脱色处理后.以其为原料和乙酸甲酯在固定化脂肪酶的催化下反应制备生物柴油.考察反应条件对酯交换反应的影响,得到的最佳条件为:煎炸废油2.0 g、固定化脂肪酶Novozym435的用量为油重的9%、有机溶剂叔丁醇2.0mL、乙酸甲酯与煎炸废油摩尔比9:1、有机碱三羟甲基氨基甲烷的用量为油重的15%、反应时间12 h、反应温度60℃、摇床转速为150 r/min.在此条件下生物柴油的得率为80.73%.     

碱性脂肪酶在正庚烷中催化合成乙酸乙酯的研究

用碱性脂肪酶在正庚烷中催化合成乙酸乙酯,探讨了加酶量、反应温度和反应时间以及采用不同的碱性脂肪酶等因素对乙酸转化率的影响。研究表明,当乙酸浓度为0.20mol/L、乙酸和乙醇的摩尔比为1∶1.25、摇床转速为150r/min、定时加入一定量的3A分子筛适当移走产物的水分时,最佳反应温度为36℃;产自扩展青霉碱性脂肪酶高产变株FS1884-1的酶A催化效果为最好;当酶A的加入量为0.30g/瓶(相当于碱性脂肪酶的加入量为1700u/g乙酸)、反应时间为48h,乙酸的转化率已基本趋于稳定,转化率达71.4%。     

Lipase-catalyzed synthesis and characterization of myristoyl maltose ester

Myristoyl maltose ester was synthesized by lipase-catalyzed reaction of maltose and myristic acid. Influence of different reaction parameters, such as molecular sieve concentration, molar ratio of acid/sugar, enzyme concentration, reaction time, and reaction temperature, was studied. Under the optimum conditions of 20 g/L molecular sieve, 14% (w/w) lipase from Novozym 435, and acid/sugar molar ratio of 5:1 at 60 °C for 60 h, the highest conversion (90%) was achieved. The as-prepared maltose ester was confirmed by Fourier-transform infrared spectra (FTIR), liquid chromatograph–mass spectrum (LC–MS), and scanning electron microscopy (SEM).     

Lipase Mediated Production of Flavor and Fragrance Esters from Fusel Oil

Mixtures of C₃, C₄ and C₅ chain length aliphatic alcohols found in fusel oil were converted to their acetic acid and butyric acid esters using a lipase (from Candida cylindracea) mediated process in a water immiscible fluid (hexane). Incubation temperature was 30°C with shaking (150 rpm). Maximum production of the mixed butyric acid ester product (0.62 mol/L; yield = 65.8%) and acetic acid ester product (0.052 mol/L; yield = 46.4%) were obtained in 48 hr. Enzyme could be reused three times before loss of activity for acetic acid ester synthesis but enzyme activity decreased after one use for butyric acid ester synthesis.     

Lipase-catalyzed production of pinolenic acid concentrate from pine nut oil using a recirculating packed bed reactor

Pinolenic acid (PLA) concentrate in fatty acid ethyl ester (FAEE) was efficiently produced from pine nut oil via lipase-catalyzed ethanolysis using a recirculating packed bed reactor (RPBR). The effects of reaction temperature, molar ratio, and residence time on the concentration of PLA were explored. Novozym 435 lipase from Candida antarctica showed less selectivity toward PLA esterified at the sn-3 position when temperature was increased from 45 to 55 °C. For the trials of molar ratio between 1: 50 and 1: 100 (pine nut oil to ethanol), there were no significant differences in the yield of PLA. Residence time of substrate in a RPBR affected significantly the PLA content as well as the yield of PLA. Optimal temperature, molar ratio (pine nut oil to ethanol), and residence time for production of PLA concentrate via lipase-catalyzed ethanolysis in a RPBR were 45 °C, 1: 50, and 3 min, respectively. Under these conditions, the maximal PLA content (36.1 mol%) in the concentrate was obtained during the initial 10 min of reaction.     

有机相脂肪酶催化合成阿魏酸乙酯

本实验研究了有机溶剂中脂肪酶催化阿魏酸乙酯合成反应。对催化合成阿魏酸乙酯反应的脂肪酶和反应介质进行了比较,最佳溶剂为叔丁醇,在所选的6种脂肪酶中,固定化于大孔丙烯酸树脂的南极假丝酵母脂肪酶B(Novozym 435)的催化活性最好。同时对影响合成阿魏酸乙酯反应的因素(底物浓度、底物摩尔比、温度、初始水含量、反应时间等)进行了探讨,优化了反应条件:在10ml无水叔丁醇中,当酸醇摩尔比为1:1,酸浓度为0.1mol/L,反应温度为60℃,反应时间为120h时产率达到最高,脂肪酶Novozym 435具有较高的稳定性,重复使用六次后产率仍然可达到23%。     

Catalytic properties of a lipase from Photobacterium lipolyticum for biodiesel production containing a high methanol concentration

Biodiesel, an alternative fuel, is generated via the transesterification reaction of vegetable oil or animal oil with alcohol. Currently, many reports have noted that microbial lipases might be utilized for the production of biodiesel. Among them, immobilized Candida antarctica lipase B (Novozym435) is frequently utilized for its biocatalytic efficiency and availability. However, as the enzyme is unstable in a medium containing high concentrations of methanol, a multi-stepwise methanol supply is required for the efficient production of biodiesel. Photobacterium lipolyticum lipase (M37) was determined to be quite stable in a medium containing a high concentration of methanol. The enzyme activity was maintained for longer than 48 h without any loss at a methanol concentration of 10%. In an effort to evaluate enzyme performance in the production of biodiesel, we have compared M37 lipase and Novozym435 in the biodiesel production reaction using fresh or waste oil and methanol. In the 3-stepwise methanol feeding method generally conducted for Novozym435 in biodiesel production, the M37 lipase showed a similar or superior conversion yield to Novozym435. However, the M37 lipase evidenced significantly higher conversion yields in the 2 and 1 step methanol feeding reactions. Particularly in the 1 step process using 10% of methanol where almost no conversion was detected by Novozym435, the biodiesel yield achieved with M37 lipase reached a level of up to 70% of the possible maximum yield. Consequently, this methanol-tolerant lipase, M37, has been shown to be a suitable enzyme for use in the biodiesel production process.     

超临界CO2状态下直接酯化法制备共轭亚油酸甘油酯

在超临界CO2状态下,采用脂肪酶催化共轭亚油酸(conjugated linoleic acid,CLA)与甘油反应制备共轭亚油酸甘油酯,分别应用单因素和正交试验考察分子筛添加量、酶用量、反应压力、温度和时间对CLA酯化率的影响。结果表明,最佳工艺条件为分子筛用量6%、酶用量4%、反应温度60℃、反应时间20h、反应压力11MPa,此条件下CLA的酯化率可达到90.98%。这种CLA甘油酯的脂肪酸组成中,9c,11t-CLA和10t,12c-CLA的含量分别为37.79%和41.66%。     

超临界CO2状态下生物酶法催化合成植物甾醇酯

对葵花油与植物甾醇在CO2 超临界状态下合成植物甾醇酯的工艺进行研究。采用Novozym 435 脂肪酶做催化剂,进行酯化反应。通过单因素与正交试验,确定了最佳工艺条件：反应温度85℃、植物甾醇质量分数5%、反应压力8MPa、反应时间1h、搅拌速度600r/min,在此条件下,转换率为92.1%。与常规方法相比,本工艺降低了反应温度,缩短了反应时间。     

Lipase-catalyzed process in an anhydrous medium with enzyme reutilization to produce biodiesel with low acid value

One major problem in the lipase-catalyzed production of biodiesel or fatty acid methyl esters (FAME) is the high acidity of the product, mainly caused by water presence, which produces parallel hydrolysis and esterification reactions instead of transesterification to FAME. Therefore, the use of reaction medium in absence of water (anhydrous medium) was investigated in a lipase-catalyzed process to improve FAME yield and final product quality. FAME production catalyzed by Novozym 435 was carried out using waste frying oil (WFO) as raw material, methanol as acyl acceptor, and 3 Å molecular sieves to extract the water. The anhydrous conditions allowed the esterification of free fatty acids (FFA) from feedstock at the initial reaction time. However, after the initial esterification process, water absence avoided the consecutives reactions of hydrolysis and esterification, producing FAME mainly by transesterification. Using this anhydrous medium, a decreasing in both the acid value and the diglycerides content in the product were observed, simultaneously improving FAME yield. Enzyme reuse in the anhydrous medium was also studied. The use of the moderate polar solvent tert-butanol as a co-solvent led to a stable catalysis using Novozym 435 even after 17 successive cycles of FAME production under anhydrous conditions. These results indicate that a lipase-catalyzed process in an anhydrous medium coupled with enzyme reuse would be suitable for biodiesel production, promoting the use of oils of different origin as raw materials.