脲包法分离不饱和脂肪酸甲酯的研究

以混合脂肪酸甲酯为原料,采用尿素包合法（脲包法）分离不饱和脂肪酸甲酯。通过正交试验,得到了最佳工艺条件：混合脂肪酸甲酯（w）：尿素（w）：甲醇（v）为1：2．09：8．36,包合温度-10℃,包合时间18h。经过一次包合,不饱和脂肪酸甲酯的含量由原来的47．69％提高到86．74％,收率54．19％。     

Enzymatic synthesis of monosaccharide fatty acid esters and their comparison with conventional products

5-O-Acyl-1,2-O-isopropylidene-D-xylofuranose and 6-O-acyl1,2∶3,4-di-O-isopropylidene-D-galactopyranose were enzymatically prepared from the corresponding monosaccharide acetals and commercial (crude) fatty acid mixtures. Subsequent acid-catalyzed hydrolysis of the isopropylidene group(s) gave monosaccharide esters with overall yields of 59–88%, where the monoester content was at least 80% (galactose oleate) and typically 90% for the other preparations. In contrast to sugar fatty acid esters prepared by conventional, high-temperature (trans)esterification, the enzymatically obtained monosaccharide esters contained no appreciable quantities of undersirable side products, and the only contaminants were monosaccharides and fatty acids.     

聚乙二醇单甲醚脂肪酸酯的碱催化合成及性能

在碱催化下通过聚乙二醇单甲醚（ＰＧＭＥ）和脂肪酸甲酯的酯交换反应合成了ＰＧＭＥ脂肪 酸酯。在酯和醇醚摩尔比为１：１．２．催化剂质量分数为０５％、反应温度１２０℃、反应时间６．５ｈ条 件下,对脂肪酸甲酯的摩尔收率可达９０％。用ＩＲ、~（１３）ＣＮＭＲ对产物结构进行了确证,同时对产物 的表面物性进行了测试。     

Enzymatic synthesis of acetylated glucose fatty acid esters in organic solvent

Two immobilized lipases fromCandida antarctica (SP 382) andC. cylindraceae, nowrugosa (2001), catalyzed the synthesis of novel acetylated glucose fatty acid esters with glucose pentaacetate (GP) and Trisun 80 (80% oleic) vegetable oil or methyl oleate as substrates in organic solvents. The relative yield was between 6.4–52%, and the incorporation of oleic acid onto the glucose was between 31–100%. In addition, these enzymes were able to catalyze the synthesis of glucose fatty acid esters with free glucose as the sugar substrate. The highest oleic acid incorporation (100%) was obtained in benzene with SP 382 lipase and Trisun 80 as the acyl donor. With methyl oleate as the acyl donor, greater incorporation was obtained in benzene (90.5%) compared to 75% in isooctane. The 2001 lipase was better in benzene/pyridine (2∶1 vol/vol) 74%) and chloroform (61%) compared to benzene and isooctane. However, with free glucose and Trisun 80 as substrates, both enzymes gave acceptable levels of oleic acid incorporation (82–100%) in benzene, benzene/pyridine and pyridine. The best conditions for the ester interchange reaction reported are: lipase (10% by weight of substrate); incubation time 48 h; molar ratio of Trisun/GP 1∶2; 3 mL solvent and 3% added water. These glucose esters have potential applications as emulsifiers in food, cosmetics and pharmaceutical formulations.     

丙二醇法合成蔗糖脂肪酸酯工业性实验

进行了由蔗糖和脂肪酸乙酯在丙二醇溶剂中经酯交换合成蔗糖脂肪酸酯(Sucrose fatty acid esters)简称蔗糖酯(SE)的300 t/a工业性实验。该合成工艺用丙醇作溶剂取代国内外沿用N,N-二甲基甲酰胺有毒溶剂的SE合成方法,工艺简单,生产成本低,易于工业化生产。该工艺合成SE收率在78%以上,SE总酯质量分数在91%以上。     

固定化Candida sp.99-125脂肪酶催化大豆油合成脂肪酸乙酯

探讨了酶法合成脂肪酸乙酯作为生物柴油的可行性. 以大豆油和乙醇为原料,利用本实验室自制的固定化Candida sp. 99-125脂肪酶催化反应,深入研究水含量、溶剂量、脂肪酶量及反应温度等因素对酶法合成脂肪酸乙酯的影响. 结果表明,以大豆油质量为基准,在水含量为 12.5%(w)、溶剂正己烷为3 mL/g、脂肪酶量为20%(w)、温度40℃的优化反应条件下,3次流加乙醇,170 r/min摇瓶反应,12 h后可以达到96.8%的最高酯得率. 进一步研究表明,在此优化反应条件下,连续使用14批脂肪酶酯得率可保持70%以上.     

In situ esterification of rice bran oil with methanol and ethanol

In situ esterifications of high-acidity rice bran oil with methanol and ethanol and with sulfuric acid as catalyst were investigated. In the esterification with methanol, all free fatty acids (FFA) dissolved in methanol were interesterified within 15 min, and it was possible to obtain nearly pure methyl esters. The amount of methyl esters obtained from a given rice bran was dependent on the FFA content of the rice bran oil. In the esterification with ethanol, it was not possible to obtain pure esters as in methanol esterification, because the solubilities of oil components in ethanol were much higher than those in methanol.     

Preparation of glycol derivatives of partially hydrogenated soybean oil fatty acids and their potential as lubricants

Glycol diesters and mixtures of mono- and diesters have been prepared from methyl esters of partially hydrogenated soybean oil fatty acids and diethylene, dipropylene, neopentyl and triethylene glycols. The catalyst used in these reactions was a mixture of calcium acetate/barium acetate (3∶1, w/w). The reactions were carried out under nitrogen with 0.5% catalyst at temperatures in the range of 190–275°C. Borated esters of mixed mono- and diesters were prepared with 0.33 equivalent of boric acid per 1.0 equivalent hydroxyl group on the ester. Refractive indices, viscosities, and flash and fire points were determined for diesters, mixed mono- and diesters, and mixed diesters and borated esters. The viscosities, flash points and fire points indicate that these esters can be used as a component of lubricating oils. Wear-prevention characteristics of mixed diesters and borated esters indicated that they can be used as antifriction additives in lubricating oils. Lecture presented at the joint meeting of the International Society for Fat Research and the American Oil Chemists' Society in Toronto, May 10, 1992.     

Optimization of fatty acid extraction from Phaeodactylum tricornutum UTEX 640 biomass

Fatty acids in the microalga Phaeodactylum tricornutum were isolated using an optimized three-step method: extraction of crude fatty acid potassium salts made by direct saponification of lipids in the microalgal biomass with KOH/ethanol (96%, vol/vol), separation of unsaponifiable lipids by extraction with hexane, and final purification of fatty acids by acidification of the alcoholic solution of potassium soaps followed by extraction of fatty acid into hexane. Direct saponification was carried out in ethanol (96%, vol/vol) using 2.09 mL ethanol (96%) per gram of wet biomass (10 mL/g of dry biomass) mixed with 0.4 g KOH/g of biomass. Under these conditions the fatty acid yield was 87%. The optimal water content of the alcoholic solution for extraction of the unsapononifiables was established as 40%, w/w. Data on equilibrium carotenoid distribution between the alcoholic (40%, w/w water) and hexane phases were determined. These data allow prediction of the carotenoid yields with different volumes of hexane in several extraction steps. The optimal pH of the alcoholic solution before extracting the purified fatty acid was established as pH 6, and the equilibrium fatty acid distribution between the alcoholic and hexane phases was determined. This optimized method permited a 20% reduction in the production costs of highly purified eicosapentaenoic acid (EPA) in the three-step preparative process (extraction of fatty acid, concentration of polyunsaturated fatty acids by the urea method, and EPA fractionation through preparative high-performance liquid chromatography) previously developed by the authors.     

Solvent-Assisted Crystallization of Fatty Acid Alkyl Esters from Animal Fat

An easy and efficient method for the separation of saturated and unsaturated fatty acid mono alkyl esters, prepared from animal fat, was developed. The most efficient separation was achieved by the use of solvents such as methanol and acetone at low temperatures. The dilution of the alkyl esters with 10 times the amount of solvent (10:1 v/w) and storage of the mixture for 4 h at ?22 °C could be defined as optimum conditions. After filtration of the saturated fraction at the corresponding temperature very pure fractions were obtained. For fatty acid methyl esters deriving from tallow, with an initial content of saturated fatty acids of almost 50 %, a saturated ester fraction with only 5 % unsaturated fatty acids and an unsaturated ester fraction with about 9 % of saturated fatty acids could be obtained. The solvent easily could be recovered by distillation. In addition fatty acid ethyl, 1‐propyl, 2‐propyl, 1‐butyl, tert‐butyl and 3‐methyl‐1‐butyl esters were prepared and separated into saturated and unsaturated fractions. All fractions were analyzed according to the fatty acid compositions and showed similar or slightly worse results compared to the methyl esters. The cold filter plugging points of the unsaturated fractions were measured, showing the lowest value for the unsaturated methyl ester fraction at ?26 °C. The fractionation with the use of solvents is an easy tool in order to obtain fatty acid alkyl esters with excellent cold temperature behavior out of animal fat.     

Lipase-catalyzed synthesis of hydroxy stearates and their properties

Hydroxy fatty acid (HFA) esters of long-chain alcohols, such as hydroxy stearates, have potential applications from lubricants to cosmetics. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. An immobilized lipase, Rhizomucor miehei, was employed as catalyst in the esterification reaction between hydroxy-stearic acid as a source of HFA and monohydric fatty alcohols (C₈–C₁₈). The yields of esters were in the range of 82–90% by conducting the reactions at 65±2°C, 2–5 mm Hg pressure, and 10% lipase concentration. The products were analyzed by infrared spectroscopy, and some of their analytical characteristics were determined.     

Enzymatic preparation of polyethylene glycol esters of castor oil fatty acids and their surface-active properties

This study concerns the preparation and evaluation of nonionic surfactants prepared from polyethylene glycol (PEG) esters of castor oil fatty acid, a source of hydroxy fatty acid. A lipase-catalyzed esterification reaction has been employed to prepare PEG esters of hydroxy acid to overcome problems associated with chemical processes. Castor oil fatty acid (85% ricinoleic acid) was mixed with PEG of different molecular weight. Rhizomucor miehei lipase was added as catalyst (10% level) and the reaction was continued at 60°C under 2 mm Hg pressure for 360 min. Conversion of PEG to esters was in the range of 86–94%, depending on the molecular size of PEG. The products were isolated and examined for surface activity by surface tension measurement. Surface tension values measured at 25°C were about 36–37 dynes/cm.     

Evaluation of sequential methods for the determination of butterfat fatty acid composition with emphasis ontrans-18:1 acids. Application to the study of seasonal variations in french butters

The successive steps of an integrated analytical procedure aimed at the accurate determination of butterfat fatty acid composition, includingtrans-18:1 acid content and profile, have been carefully checked. This sequential procedure includes: dispersion of a portion of butter in hexane/isopropanol (2:1, vol/vol) with anhydrous Na₂SO₄, filtration of aliquots of the suspension through a microfiltration unit, subsequent preparation of fatty acid isopropyl esters (FAIPE) with H₂SO₄ as a catalyst, and analysis of total FAIPE by capillary gas-liquid chromatography (GLC). Isolation oftrans-18:1 isomers was by silver-ion thin-layer chromatography (Ag-TLC), followed by extraction from the gel of combined saturated andtrans-monoenoic acids with a biphasic solvent system. Analysis of these fractions by GLC allows the accurate quantitation oftrans-18:1 acids with saturated acids (14:0, 16:0, and 18:0) as internal standards. A partial insight in the distribution oftrans-18:1 isomers can be obtained by GLC on a CP Sil 88 capillary column (Chrompack, Middelburg, The Netherlands). All steps of the procedure are quite reproducible, part of the coefficients of variation (generally less than 3%, mainly limited to butyric and stearic acids) being associated with GLC analysis (injection, integration of peaks) and, to a lesser extent, to FAIPE preparation. FAIPE appear to be of greater practical interest than any other fatty acid esters, including fatty acid methyl esters (FAME), for the quantitation of short-chain fatty acids, because peak area percentages, calculated by the integrator coupled to the flame-ionization detector, are almost equal (theoretically and experimentally) to fatty acid weight percentages and do not require correction factors. With this set of procedures, we have followed in detail the seasonal variations of fatty acids in butterfat, with sixty commercial samples of French butter collected at five different periods of the year. Important variations occur around mid-April, when cows are shifted from forage and concentrates during winters spent in their stalls to fresh grass in pastures. At this period, there is a decrease of 4:0–14:0 acids and of 16:0 (−2 and −6%, respectively), while 18:0 andcis- plustrans-18:1 acids rise suddenly (2 and 5%, respectively). These modifications then progressively disappear until late fall or early winter. Other variations are of minor quantitative importance. Although influenced by the season, the content of 18:2n-6 acid lies in the narrow range of 1.2–1.5%.Trans-18:1 acids, quantitated by GLC after Ag-TLC fractionation, are at their highest level in May–June (4.3% of total fatty acids), and at their lowest level between January and the end of March (2.4%), with a mean annual value of 3.3%. The proportion of vaccenic (trans-11 18:1) acid, relative to totaltrans-18:1 isomers, is higher in spring than in winter, with intermediate decreasing values in summer and fall, which supports the hypothesis that the level of this isomer is linked to the feed of the cattle, and probably to the amount of grass in the feed.     

Biodegradability of biodiesel fuel of animal and vegetable origin

One of the positive features of biofuel concerning environmental protection is its high biodegradability. Fuel is considered to be biodegradable if not less than 90% of it degrades within 21 days. The aim of this work was to determine the biodegradability of various kinds of fatty acid methyl esters and their mixtures with fossil diesel fuel in natural environments. It was determined that fatty acid methyl esters meet the requirements for biodegradability set by the EU. Of rapeseed oil fatty acid methyl esters (RME), 91.2% degraded within 21 days, compared to 94.2% of rapeseed oil fatty acid ethyl esters, 98.3% of linseed oil fatty acid methyl esters (LSME), 90% of tallow fatty acid methyl esters, and 92.5% of pork lard fatty acid methyl esters (LME), while the amount of degraded fossil diesel fuel reached only 57.3%. The biodegradability of multi‐component biofuels containing RME, LSME and LME is similar; the best is of a mixture of 70% RME, 6% LSME and 24% LME. It was determined that more than 90% of multi‐component biofuel and fossil diesel fuel mixtures degrade within 21 days when they contain 35% and more of multi‐component biofuel.     

Chemo-enzymatic synthesis of disaccharide fatty acid esters

A novel enzymatic method for the synthesis of disaccharide fatty acid esters was developed with immobilizedMucor miehei lipase (Lipozyme IM-60; Novo Nordisk, Bagsvaerd, Denmark) as a catalyst. A range of lactose and maltose monoesters was prepared in overall yields of 48–77% from the corresponding sugar acetals and fatty acids.     

In-situ alcoholysis of soybean oil

In-situ alcoholysis of soybean oil with methanol, ethanol,n-propanol, andn-butanol was investigated, as well as the extraction of the oil with these solvents, to explain the progress ofin-situ alcoholysis and to determine the parameters that affect this reaction. Because methanol is a poor solvent for soybean oil, the amount of oil dissolved in methanol and converted to methyl esters was low afterin-situ alcoholysis. Ethyl, propyl, and butyl esters of soybean fatty acids could be obtained in high yields fromin-situ alcoholysis of soybean oil with these alcohols.In-situ alcoholysis proceeded through dissolution and alcoholysis of triglycerides successively, and the overall reaction rate was determined by the extraction and alcoholysis rates. The parameters, affecting yield and purity of the product esters, were mainly those that favor extraction rate.     

Enzymatic synthesis of fatty alcohol esters by alcoholysis

Lipase-catalyzed conversions of some minor oils and fats like mowrah (Madhuca latifolia), mango (Mangifera indica) kernel, and sal (Shorea robusta) fats into low, medium, and high molecular weight alcohol esters have been investigated. In solvent-free medium, alcoholysis of the above-mentioned fats with 10% (w/w) Mucor miehei lipase produced alcohol esters in good yield. The percentage molar conversions of C₄, C₈, C₁₀, C₁₂, C₁₄, C₁₆, C₁₈, and C_18:1 alcohols into corresponding alcohol esters ranged from 86.8 to 99.2, while the percentage molar conversions on the basis of oil were in the range of 108.0 to 123.5.     

Medium-chain fatty acid-rich glycerides by chemical and lipase-catalyzed polyester-monoester interchange reaction

Medium-chain triglycerides (MCT) that contain caprylic acid (C_8:0) and capric acid (C_10:0) have immense medicinal and nutritional importance. Coconut oil can be used as a starting raw material for the production of MCT. The process, based on the interchange reaction between triglycerides and methyl esters of medium-chain fatty acids by chemical catalyst (sodium methoxide) or lipase (Mucor miehei) catalyst, appears to be technically feasible. Coconut oils with 25–28.3% (w/w) and 22.1–25% (w/w) medium-chain fatty acids have been obtained by chemical and lipase-catalyzed interchange reactions. Coconut olein has also been modified with C_8:0 and C_10:0 fatty acids, individually as well as with their mixtures, by chemical and lipase-catalyzed interchange reactions. Coconut olein is a better raw material than coconut oil for production of mediumchain fatty acid-rich triglyceride products by both chemical and lipase-catalyzed processes.     

Impact of Fatty Acid Structure on CALB‐Catalyzed Esterification of Glucose

Enzymatic synthesis of fatty acid glucose esters from different fatty acyl donors are performed via enzymatic catalysis in the presence of Candida antarctica lipase B (CALB), using acetonitrile as the solvent. The acyl donor nature (fatty acid or fatty acid vinyl ester) and structure are varied. Lower reaction rates and lower conversions are obtained with fatty acids in comparison to their corresponding vinyl esters. Moreover, the acyl donor with the longest chain length gives the highest conversions. The presence of unsaturation on the acyl donor chain is also shown to be detrimental to the conversion. Practical Applications: The practical applications of the present work are related to the production of gluco‐esters that could be used as nonionic surfactants as detergents, cosmetics and food emulsifiers, emollients or conservatives, respectively. In this study, it is shown that in order to get high production yields, each reaction parameter has to be tuned properly.     

Esterification of palm fatty acid distillate (PFAD) in supercritical methanol: Effect of hydrolysis on reaction reactivity

This study demonstrated the potential use of local palm fatty acid distillate (PFAD) as alternative feedstock for fatty acid methyl esters (FAMEs) production and the possibility to replace the conventional acid-catalyzed esterification process (with H₂SO₄), which was industrially proven to suffer by several corrosion and environmental problems, with non-catalytic process in supercritical methanol. At 300 °C with the PFAD to methanol molar ratio of 1:6 and the reaction time of 30 min, the esterification of PFAD in supercritical methanol gave FAMEs production yield of 95%. Compared with transesterification of purified palm oil (PPO) in supercritical methanol, the production of FAMEs reached the maximum yield of only 80% at 300 °C with higher requirement for methanol (1:45 PPO to methanol molar ratio). Compared with the conventional acid-catalyzed esterification of PFAD, only 75% FAMEs yield was obtained in 5 h. The presence of water in the feed (between 0 and 30% v/v) was found to lower the yield of FAMEs production from PFAD significantly. This negative effect was proven to be due to the further hydrolysis of FAMEs, which nevertheless can be minimized when high content of methanol was used.