非水相酶促合成L-抗坏血酸辛酸酯及其结构表征

以中链脂肪酸正辛酸为酰基供体,在有机相体系中利用脂肪酶催化酯化反应合成L-抗坏血酸辛酸酯。根据初步试验结果,选取对L-抗坏血酸酯化转化率影响显著的因素,进行响应面试验设计,建立回归模型,得到最优参数组合。结果表明:反应时间、反应温度、反应时间和反应温度的交互作用以及反应时间和底物浓度的交互作用对L-抗坏血酸酯化转化率均有显著影响(p0.05),回归模型可用。L-抗坏血酸辛酸酯酶法合成最优工艺条件为反应时间11.45 h、底物(L-抗坏血酸)浓度0.24 mol/L、反应温度55.3℃、脂肪酶用量(以L-抗坏血酸质量计)19.18%,此条件下L-抗坏血酸酯化转化率可达83.31%。产物经IR、MS、1H NMR和13C NMR结构表征,证实正辛酸被引入到了L-抗坏血酸的第6位羟基上。     

L-抗坏血酸不饱和脂肪酸酯的酶法合成工艺

以不饱和脂肪酸含量高的食用油为酰基供体,研究了脂肪酶在有机溶剂中通过酯交换反应催化合成L-抗坏血酸不饱和脂肪酸酯的工艺条件。结果表明,在20 m L用分子筛充分除水的叔丁醇中,0.35 g抗坏血酸与3.72 g油茶籽油(L-抗坏血酸和脂肪酸的底物摩尔比为1∶6)在150 mg脂肪酶Novozym 435的催化下,反应初始加入1.0 g分子筛4?,温度55℃,转速200 r/min,反应36 h后底物转化率可达65%。     

超声辅助脂肪酶催化L-抗坏血酸脂肪酸酯的合成

采用猪油和抗坏血酸为原料,通过单因素试验和正交试验,研究超声作用对酶促转酯化反应合成抗坏血酸脂肪酸酯的影响,并确定其最佳反应条件。结果表明,最佳反应条件为:叔戊醇为溶剂,Novozym 435用量20%(抗坏血酸质量百分比),抗坏血酸与猪油物质的量的比1:3,超声功率350W,超声频率59kHz,反应时间9h,在此条件下,抗坏血酸脂肪酸酯转化率达到88.00%。超声处理不仅可以提高产物产率(从71%提高到88%),还可以大大缩短反应时间(从32h降低到9h)。超声条件下Novozym 435有良好的操作稳定性,反应6批次后,酶活还保持在比较高的水平。     

酶促反应合成葡萄糖硬脂酸酯的研究

以Novozym435脂肪酶为催化剂,正己烷为有机溶剂,丙二醇为乳化剂,酶促合成葡萄糖硬脂酸酯.考察了脂肪酶加入量、反应温度、反应时间、底物配比、体系含水量、振荡速率对酶促酯化反应的影响,确定了酶促反应的工艺条件;同时对产物进行了定性、定量分析.研究结果表明:酶加入量为脂肪酸质量的10%,底物酸、糖的摩尔比为1:1,温度为60℃,含水量为有机溶剂的5.3%,反应时间为4.5 h,振荡速率为100r/min时,硬脂酸最大转化率可达93.40%.     

L-抗坏血酸辛酸酯的酶法合成及性质研究

在叔丁醇体系中,Novozym 435固定化脂肪酶催化L-抗坏血酸和中链脂肪酸正辛酸发生酯化反应合成L-抗坏血酸辛酸酯(L-AO),在底物(L-抗坏血酸)浓度0.2 mol/L、底物摩尔比6:1、脂肪酶用量20%、反应温度55℃、分子筛添加量60 mg/mL条件下反应12 h,L-抗坏血酸酯化转化率可达85.6%。DSC分析结果表明L-AO具有较低的结晶温度和较高的结晶焓,使其在低温时不易结晶析出。油溶性测定结果显示,L-AO在植物油中的溶解度远远大于L-抗坏血酸棕榈酸酯(L-AP),较高的油溶性有利于扩展其在油脂及脂溶性产品中的应用。羟自由基清除能力以及对油脂的抗氧化性能试验结果表明L-AO具有较强的抗氧化能力,是一种很有潜力的油溶性抗氧化剂。     

非水相酶促酯交换法合成抗坏血酸脂肪酸酯

研究了一种L-抗坏血酸脂肪酸酯（AFAE）合成新途径。实验结果表明，氢化棕榈油、大豆油和海狗油等食用油脂作为脂肪酸基团供体，在固定化脂肪酶的催化下，在有机溶荆中与L-抗坏血酸直接进行酯交换反应形成L-抗坏血酸脂肪酸酯。对反应介质体系的筛选发现，在叔戊醇中用Novozym435催化此反应所得的产物浓度最高。对影响合成抗坏血酸脂肪酸酯的因素进行了探讨，确定了最适反应条件：初始油脂底物浓度为200-600mmol／L，温度为55℃，反应时间为9h。此条件下产物质量浓度可达43．51g／L。     

脂肪酶催化麦芽糖硬脂酸酯合成的研究

脂肪酸糖酯是一类用可再生资源合成的、无毒、易生物降解的非离子型表面活性剂,具有良好的乳化性、稠化性和膨化性,应用于食品、化妆品、制药和洗涤产品,是近20年来发展较快的一类乳化剂,以蔗糖酯为主,麦芽糖硬脂酸酯是一种新型的糖酯类乳化剂.本文利用固定化脂肪酶在有机溶剂中催化麦芽糖浆和硬脂酸的合成反应,研究了反应体系中脂肪酶的加入量、反应时间、反应温度、底物配比、体系含水量等因素对催化麦芽糖硬脂酸酯反应的影响规律,确定了酶促反应的工艺条件,同时对产物进行了定性、定量分析.研究结果表明:酶加入量为10.0%,反应温度75℃、含水量为有机溶剂的10.0%,底物中酸、糖的摩尔比为1:1,反应时间24h,在该条件下,酯化反应的最大转化率可达61.3%.     

猪油酸解制备人乳脂替代品的研究

猪油Sn-2位富含棕榈酸,是制备人乳脂替代品很好的原料.以猪油和植物油脂肪酸混合物为底物,Lipozyme RM IM酶为催化剂进行酸解反应制备人乳脂替代品.实验确定最佳条件为:猪油与混合脂肪酸质量比为1:1.5,加酶量为底物质量的5%,反应温度60℃,反应时间1.5 h,反应后得到总脂肪酸组成及Sn-2位脂肪酸组成类似于人乳的乳脂替代品.     

反应条件对固定化脂肪酶转酯化合成维生素A棕榈酸酯的影响研究

目的:以维生素A醋酸酯和棕榈酸为底物,对影响固定化酶转酯化合成维生素A棕榈酸酯的条件因素进行系统研究。方法:以转化率为主要指标,辅以考虑降解,研究有机溶剂、加酶量、反应时间、底物物质的量、底物浓度和反应批次对转酯化的影响。结果:有机溶剂疏水性增加,转化率呈现幂指数形式增加,降解率随之降低;转化反应对加酶量、反应时间及底物物质的量有量的依赖效应,即在数量较低的条件下对转化率有影响,而在数值较高时对转化率没有影响;转化时间越长,降解率越大;底物物质的量比越大,降解率越低。随着底物浓度的增加,转化率呈现负幂指数形式降低,而降解率呈线性增加;乘幂函数模型比线性模型能更好地描述固定化脂肪酶反应初速度与底物浓度的关系。固定化酶在反应转酯化合成维生素A棕榈酸酯过程中的稳定性好,可以连续使用多次。结论:阐明了条件因素对酶法转酯化合成维生素A棕榈酸酯的影响,初步优化了反应条件,为进一步工艺优化提供了基础数据。     

混合溶剂中酶法催化合成木糖酯及其结构鉴定研究

本文建立了一种木糖酯合成的新方法,利用正己烷/吡啶(25:75,V/V)双溶剂体系作为反应介质,在溶解极性底物糖的同时保持酶的良好活性。采用固定化脂肪酶Novozyme 435在该体系中催化甲基丙烯酸乙烯酯和木糖的酯交换反应合成木糖酯。HPLC检测结果表明,当木糖与甲基丙烯酸乙烯酯的摩尔比为1:10,转速为150 r/min时该酶促反应具有较高的转化率,反应48 h后木糖转化率高于90%。GC-MS和核磁共振碳谱(13C-NMR)鉴定表明,在该反应条件下,Novozyme 435可选择性催化木糖的1′,5′-羟基酰化,得到产物为木糖的1′,5′-双酯。该研究为应用在食品、化学及造纸工业上的两性化合物的生产提供了一种有效并且环境友好的新方法。     

Enzymatic synthesis of lard-based ascorbyl esters in a packed-bed reactor: Optimization by response surface methodology and evaluation of antioxidant properties

An optimal continuous production of lard-based ascorbyl esters (LBAEs) by transesterification of lard with l-ascorbic acid in a packed bed reactor (PBR) was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-amyl alcohol solvent system. Response surface methodology (RSM) and central composite design (CCD) were employed to evaluate the effects of substrate flow rate, reaction temperature and substrate molar concentration ratio on the molar conversion of LBAEs. The optimum conditions were as follows: substrate flow rate 1.07 ml/min, reaction temperature 56.44 °C, and substrate molar concentration ratio 2.24:1. The optimum predicted LBAEs yield was 50.83% and the actual value was 50.50%. The above results shows that the RSM study based on CCD is adaptable for LBAEs yield studied for the current transesterification system. The antioxidant activities of LBAEs has also been studied. LBAEs represented positive antioxidant potential on superoxide anion radical and hydroxyl radicals and satisfactory antioxidant activity in lard and soybean oil. The results suggest that LBAEs has the potential to serve as natural antioxidant in food system.     

响应曲面法优化母乳化结构油脂制备工艺

文中对母乳化结构油脂的制备工艺进行优化。选用Sn-2位富含棕榈酸的猪油为原料,以Sn-1,3专一性脂肪酶Lipozyme RM IM作催化剂,与游离脂肪酸进行酶促酯交换反应制备母乳化结构油脂。通过单因素试验和响应面法优化工艺参数,建立了合成产物中Sn-2棕榈酸分布与反应温度、底物比酰基供体与猪油摩尔比、反应时间、加酶量之间的二次回归模型,即Y=-2 304.15+63.75 A+129.27 B+158.19C+45.85D-0.28AB-1.21AC-0.12AD-6.02BC-0.36BD+3.62CD-0.50A2-24.64 B2-52.00C2-2.05D2。优化后的工艺条件为:反应温度60.42°C;底物酰基供体与猪油的摩尔比为2.08∶1;反应时间1.05 h,酶/底物10.15%,制得的结构油脂中棕榈酸含量为20.35%,其中71.68%位于Sn-2位,与母乳脂肪的结构基本一致。表明采用RSM优化得到的酶促酯交换工艺条件参数适合以猪油为原料,制备母乳化结构油脂,建立的模型可以进行准确可靠的预测。     

Optimisation of kojic acid monolaurate synthesis with lipase PS from Pseudomonas cepacia

To improve the instability of kojic acid in food and cosmetic use, the esterification of kojic acid catalysed by lipase from Pseudomonas cepacia (Amano PS) to synthesise kojic acid monolaurate (KAML) was investigated in this study. Response surface methodology (RSM) with a five‐level/five‐factor central composite rotatable design (CCRD) was employed to evaluate the effects of synthesis parameters such as reaction time (8–24 h), temperature (35 55 °C), enzyme amount (10–50%), substrate molar ratio of lauric acid to kojic acid (1:1–3:1) and added water content (0–20%) on the percentage molar conversion to KAML by direct esterification. Reaction time and added water content were the most important variables, while substrate molar ratio had less effect on percentage molar conversion. Based on canonical analysis and ridge maximum analysis, optimal synthesis conditions were reaction time 19 h, temperature 44 °C, enzyme amount 38%, substrate molar ratio 2:1 and added water content 10%. The predicted value was 85% and the actual experimental value 82% molar conversion. © 2002 Society of Chemical Industry     

猪脂控制氧化及挥发性氧化产物研究

通过单因素试验和正交试验研究以热反应制备肉味香精前体物为目的的猪脂肪控制氧化工艺条件。以过氧化值(POV)、硫代巴比妥酸值(TBA)和酸值(AV)表征油脂的氧化状态。结果表明,猪脂肪控制氧化的较佳工艺条件为：反应温度120℃、反应时间2h、氧气流速0.025m3/h。采用固相微萃取- 气质联用技术对猪脂肪控制氧化产物中的挥发性成分进行分析,共鉴定出32 种化合物,其中醛类化合物占52.52%,为猪脂肪控制氧化产物中的主要挥发性成分。     

Lipase‐catalysed biosynthesis of hexyl butyrate by direct esterification: optimisation by response surface methodology

The ability of immobilised lipase from Rhizomucor miehei (Lipozyme IM‐77) to catalyse the direct esterification of hexanol and butyric acid was investigated. Response surface methodology (RSM) and a four‐factor/five‐level central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters such as reaction time (2–10 h), temperature (25–65 °C), substrate molar ratio of hexanol to butyric acid (1:1–3:1) and enzyme amount (10–50%; 0.24–1.18 BAUN) on the percentage molar conversion of hexyl butyrate by direct esterification. All the parameters had significant effects on the percentage molar conversion. Based on ridge maximum analysis, the optimal conditions for synthesis were: reaction time 8.0 h, temperature 46.9 °C, substrate molar ratio 1:1.2 and enzyme amount 36.4% (0.87 BAUN). The predicted value was 100% and the actual experimental value 98.2% molar conversion. Copyright © 2003 Society of Chemical Industry     

Enzymatic lipophilisation of phenolic acids through esterification with fatty alcohols in organic solvents

We investigated and optimised the synthesis of lipophilized esters between selected phenolic acids and fatty alcohols in a binary solvent system, composed of hexane and butanone. The effect of proportions of hexane and butanone was first studied by varying the volume ratio of hexane/butanone from 85:15 to 45:55. It was found that the conversion of phenolic acids strongly depended on the proportions of hexane and butanone. To examine the effect of carbon chain length of fatty alcohols on the reaction rate, the esterifications of C4-C18 straight-chain fatty alcohol with dihydrocaffeic acid (DHCA), as a model phenolic acid, were systematically evaluated. The results indicated that the conversion of DHCA was significantly affected by the number of carbon chain of fatty alcohols. Roughly 95% conversion was achieved within 3 days when hexanol was used as an acyl acceptor; while only 56% and 44% conversions were achieved when 1-butanol and octadecanol were employed, respectively. However, the conversions of ferulic and caffeic acids under the same conditions were much lower than was that of DHCA. The optimal mixture ratio of hexane to butanone was found to be 65:35. Using the reaction of octanol and DHCA as a model, the reaction parameters, such as temperature, enzyme load, reaction time and substrate molar ratio, were optimised with response surface methodology (RSM). A second polynomial model was generated and optimised reaction conditions were obtained as: temperature 60 °C, reaction time 3.9 days, enzyme load 238 mg, and substrate molar ratio 3.6 (octanol/DHCA). A validation reaction, based on the optimal conditions, was conducted, to yield 94.5% conversion of DHCA, indicating the suitability of the RSM model.     

基于改性Pt/SAPO-11催化废猪油制备航空煤油的工艺优化

使用经柠檬酸改性的Pt/SAPO-11催化废猪油一步加氢制备航空煤油。在单因素实验的基础上,采用响应面实验进行工艺优化,得到改性Pt/SAPO-11催化废猪油一步加氢制备航空煤油的最佳工艺条件为反应温度290.63℃、反应时间3.94 h、转速148.55 r/min、反应氢压3 MPa、油料比10∶1 (废猪油与催化剂质量比),在此条件下C8~C16烷烃含量为71.34%,烷烃异构率为8.94%。产品经后续精馏等工序处理,可达到国标3号航空煤油标准。     

几种醇对Lipozyme RM IM催化卵磷脂乙醇解的影响及其工艺条件优化

研究脂肪酶Lipozyme RM IM催化大豆卵磷脂（phosphatidylcholine,PC）乙醇解反应制备溶血卵磷脂（lysophosphatidylcholine,LPC）过程中其他几种醇对PC乙醇解的影响,并对乙醇解条件进行了优化。发现正丁醇对PC乙醇解无明显影响,叔丁醇对PC乙醇解有一定的抑制作用,1,2-丙二醇和丙三醇呈现较好的促进作用。最后选用丙三醇作为乙醇解的促进剂,通过响应面分析法确定了无溶剂体系中Lipozyme RM IM催化PC醇解的最佳工艺条件为加酶量15%（以PC质量计,m/m）、反应温度28 ℃、加水量8%（水/乙醇溶液,V/V）、丙三醇10% （丙三醇/乙醇溶液,V/V）、底物质量浓度1.49 g/mL（PC/乙醇溶液,m/V）、反应时间11 h,此条件下 LPC转化率高达98.2%。实验证明,丙三醇对无溶剂体系中Lipozyme RM IM催化条件下的PC乙醇解反应有很好的促进作用。     

麦芽糖醇脂肪酸酯的酶催化合成及表面张力测定

以脂肪酶为催化剂,以麦芽糖醇和脂肪酸为原料合成麦芽糖醇脂肪酸酯。通过考察原料配比、催化剂的用量、反应时间、溶剂用量等主要因素对反应的影响,确定最佳反应条件。结果表明,以脂肪酶 Novozym 435为催化剂,脂肪酶用量为0.24g/mmol 脂肪酸,溶剂丙酮的用量为10mL/mmol 脂肪酸,麦芽糖醇:脂肪酸为2:1(mol/mol),在60℃条件下反应80h,脂肪酸的转化率为91%～95%。当麦芽糖醇脂肪酸酯溶液质量分数为0.06% 时,表面张力为38～40mN/m。     

Optimization of Sucrose Polyester Synthesis Using Response Surface Methodology

Response Surface Methodology (RSM) was used to evaluate the effects of synthetic variables such as reaction time (6–12 hr), temperature (130–150°C), and substrate molar ratio of fatty acid methyl esters (FAME) of peanut oil to sucrose (10:1 to 14:1) on the % molar conversion to sucrose polyester, utilizing 10g of free sucrose as the reactant. Optimization of the synthetic reaction was performed by canonical analysis to derive the stationary point. Based on contour plots and canonical analysis, optimum conditions were: reaction time 11.5 hr, synthetic temperature 144°C, and substrate molar ratio 11.4:1. Predicted molar conversion was 43.39% (10g sucrose synthesized 29.4g sucrose polyester) at the optimum point. Experimental data indicated up to 48.4% yield based on theoretical % molar conversion.