Herstellung,Analyse und DC-Trennung von Fettsäure-Erythritpartialestern

Preparation, Analysis and TLC Separation of Partial Esters of Fatty Acids with Erythritol Direct esterification of 99% capric acid, lauric acid, myristic acid, palmitic acid and stearic acid with meso-erythritol (1,2,3,4-butanetetraol) in mole ratio of 1 : 1.25 yielded partial esters of erythritol which were analyzed by chemical values and TLC separation. Using boric acid impregnated silica gel 60 precoated plates all the theoretically possible positional isomers of mono-, di-, tri- and tetraesters of erythritol (9 fractions) and further four 3,4-hydroxy-tetrahydrofuran-mono- and diesters (both cis- and trans compounds), that were formed as side products by dehydration and 1,4 ring closure from 1,2,3,4-butanetetraol, could be detected. Similarly, the unknown TLC fraction of 1,2,4-butanetriol partial ester, as reported earlier, could be identified as 3-hydroxy-tetrahydrofuran fatty ester by chemical values, elementary analysis, molecular weight determination and synthesis. Moreover, erythritol, 1,2,4-butanetriol, 3,4-hydroxy-tetrahydrofuran and 3-hydroxy-tetrahydrofuran were separated by TLC.     

Medium chain length fatty acid esters and their medical and nutritional applications

Caprylic and capric acid esters and their applications in medical, nutritional and dietetic uses are described. Medium chain triglycer-ides (MCT) as a tool in the control of obesity, control in the choles-terol deposition in the tissues as well as a means of lowering serum cholesterol are cited as unique characteristics of such lipids. MCT as a source of quick energy and high energy is suggested as an alterna-tive to the conventional fats and oils (LCT). Dietetic and nutritional application utilizing the unique characteristics of caprylic and capric acid esters is indicated as alternatives to conventional fats and oils. The mono-diglycerides of caprylic and capric acid as cholesterol dis-solving agents in treating of patients having cholesterol gallstones is described to illustrate the unique solvency properties of such mono esters in medical applications. The possibility of such mono esters of di- and polyhydric alcohols to act as co-solvents for oil and water systems is suggested which can be applied in medical, pharmaceuti-cal and allied fields. Structured lipids with a predominance of capry-lic and capric acid to modify the properties of triglycerides is described for hyperalimentation uses as well as the special nutri-tional and dietetic needs.     

Fatty acid and oil diversity of cupheaviscosissima: A source of medium- chain fatty acids

Cuphea viscosissima Jacq. is being developed as a commercial source of caprylic, capric, lauric, and myristic acids. Germplasm resources for characterizing the genetic diversity of this species became available following explorations by the United States Department of Agriculture (USDA) in 1986 and 1987. In this paper, we describe the fatty acid and oil percentage diversity of forty- two populations ofC. viscosissima collected from seven states within the United States. Caprylic (18.0%) and capric acid (69.9%) were the major fatty acids of these populations. The fatty acid percentage ranges were narrow for every fatty acid,e.g., 16.4 to 20.4% for caprylic acid and 66.6 to 71.3% for capric acid. The maximum lauric acid percentage was 3.4%. Oil ranged from 27.3 to 33.4%. Although the populations surveyed cover a fairly wide geographic range, they display limited fatty acid diversity. Surveys of germplasm from other parts of the range are needed to further characterize the fatty acid diversity of this species. To whom correspondence should be addressed.     

Synthesis of Fatty Acid Esters of Selected Higher Polyols Over Homogeneous Metallic Catalysts

Studies on the synthesis of esters of natural origin fatty acids (oleic acid) and a branched synthetic isostearic acid derived from oleic acid with commercially available selected higher polyols in the presence of homogeneous metallic catalysts have been carried out. The effects of the synthesis temperature, molar ratio and the catalysts amount have also been studied. It was shown that higher fatty acid conversion and selectivity to tri‐ and tetraesters were obtained for organotin catalyst Fascat 2003, which was used as the esterification catalyst. Anti‐wear test confirmed good tribological properties of the obtained esters.     

Minor Seed Oils XVI: Examination of Fifteen Seed Oils

Fifteen seed oils from nine plant families have been examined. Oleic acid is the major component in all the oil samples, maximum being in Amaranthus tricolor (91.0%), except in the seed oil of Physalis maxima. All the samples contain arachidic and behenic acids. The oil samples from Ipomoea species and from Physalis maxima contain the lower fatty acids (caprylic and capric). Linolenic acid is found in eleven samples and lauric acid in all the seed oils except the seed oil of Celosia cristata.     

Comparison of the Structures of Triacylglycerols from Native and Transgenic Medium-Chain Fatty Acid-Enriched Rape Seed Oil by Liquid Chromatography–Atmospheric Pressure Chemical Ionization Ion-Trap Mass Spectrometry (LC–APCI-ITMS)

The sn position of fatty acids in seed oil lipids affects physiological function in pharmaceutical and dietary applications. In this study the composition of acyl-chain substituents in the sn positions of glycerol backbones in triacylglycerols (TAG) have been compared. TAG from native and transgenic medium-chain fatty acid-enriched rape seed oil were analyzed by reversed-phase high performance liquid chromatography coupled with online atmospheric-pressure chemical ionization ion-trap mass spectrometry. The transformation of summer rape with thioesterase and 3-ketoacyl-[ACP]-synthase genes of Cuphea lanceolata led to increased expression of 1.5% (w/w) caprylic acid (8:0), 6.7% (w/w) capric acid (10:0), 0.9% (w/w) lauric acid (12:0), and 0.2% (w/w) myristic acid (14:0). In contrast, linoleic (18:2n6) and alpha-linolenic acid (18:3n3) levels decreased compared with the original seed oil. The TAG sn position distribution of fatty acids was also modified. The original oil included eleven unique TAG species whereas the transgenic oil contained sixty. Twenty species were common to both oils. The transgenic oil included trioctadecenoyl-glycerol (18:1/18:1/18:1) and trioctadecatrienoyl-glycerol (18:3/18:3/18:3) whereas the native oil included only the latter. The transgenic TAG were dominated by combinations of caprylic, capric, lauric, myrisitic, palmitic (16:0), stearic (18:0), oleic (18:1n9), linoleic, arachidic (20:0), behenic (22:0), and lignoceric acids (24:0), which accounted for 52% of the total fat. In the original TAG palmitic, stearic, oleic, and linoleic acids accounted for 50% of the total fat. Medium-chain triacylglycerols with capric and lauric acids combined with stearic, oleic, linoleic, alpha-linolenic, arachidic, and gondoic acids (20:1n9) accounted for 25% of the transgenic oil. The medium-chain fatty acids were mainly integrated into the sn-1/3 position combined with the essential linoleic and alpha-linolenic acids at the sn-2 position. Eight species contained caprylic, capric, and lauric acids in the sn-2 position. The appearance of new TAG in the transgenic oil illustrates the extensive effect of genetic modification on fat metabolism by transformed plants and offers interesting possibilities for improved enteral applications.     

Enzymatic synthesis of polyglycerol-fatty acid esters in a solvent-free system

The enzymatic transesterification of fatty acid methyl esters from vegetable oil and polyglycerol has been successfully performed in the presence of Lipozyme without any solvent. The optimal conditions to obtain a mixture with lipophilic tensioactive properties were found to be a molar ratio of fatty acid methyl esters and polyglycerol of 1.33:1 at 60°C. Evaporation of the methanol produced in this reaction increased the yield of the reaction. Moreover, for this reaction, adsorption of the polyol on silica gel prior to the transesterification allowed the completion of the reaction and improved the kinetic properties. Hydrophile-lipophile balance and surface activity of the polyglycerol esters were measured to determine the emulsifying properties of these molecules.     

Search for new industrial oils,IX.Cuphea,a versatile source of fatty acids

Seed oils from five species ofCuphea show three distinct patterns of fatty acid composition.C. hookeriana andC. painteri oils contain ca. 70% caprylic acid,C. ignea and C.llavea oils have over 80% capric acid, andC. carthagenensis oil contains 57% lauric and 18% capric acids. No. Utiliz. Res. and Dev. Div., ARS, USDA ARS, USDA     

Synthesis of plant sterol esters catalyzed by heteropolyacid in a solvent‐free system

The synthesis of phytosteryl esters is of importance due to their recent recognition and application as cholesterol‐lowering agents in the food and nutraceutical industries. In this study, a synthetic route potentially useful for the large‐scale production of food‐grade phytosteryl esters with high yield and purity in a solvent‐free system was investigated. To examine the feasibility of replacing sodium methylate by heteropolyacid, four heteropolyacids, tungstosilicic acid, tungstophosphoric acid, molybdosilicic acid and molybdophosphoric acid, were evaluated to determine the best catalyst and the optimum conditions for the esterification reaction between various fatty acids and phytosterols. The results suggested that tungstosilicic acid was more selective towards butyric acid and caprylic acid than towards lauric acid, palmitic acid, and oleic acid. However, there was no significant discrimination in terms of the tungstosilicic acid catalyst's selectivity to stearic acid, oleic acid, linoleic acid and alpha‐linolenic acid, all with C18 chains, in the esterification reaction. The yield of phytosteryl ester was higher than 90% when the esterification reaction was carried out at 150 °C, with phytosterols and fatty acids in a molar ratio of 1 : 1.5, and catalyzed by 0.2% tungstosilicic acid in silica gel. The catalysts recovery experiments suggested that the immobilized tungstosilicic acid did not significantly lose its activity in six operation runs. As a result, the immobilized tungstosilicic acid would be a promising catalyst for replacing sodium methylate, to synthesize phytosteryl esters with fatty acids and phytosterols as the starting materials in a commercial production.     

Chemoenzymatic synthesis: a strategy to obtain xylitol monoesters

BACKGROUND: Fatty acid sugar esters are used as non‐ionic surfactants in cosmetics, foodstuffs and pharmaceuticals. In particular, monoesters of xylitol have attracted industrial interest due to their outstanding biological activities. In this work, xylitol monoesters were obtained by chemoenzymatic synthesis, in which, first, xylitol was made soluble in organic solvent by chemo‐protecting reaction, followed by enzymatic esterification reaction using different acyl donors. A commercial immobilized Candida antartica lipase was used as catalyst, and reactions with pure xylitol were carried out to generate data for comparison. RESULTS: t‐BuOH was found to be the most suitable solvent to carry out esterification reactions with both pure and protected xylitol. The highest yields were obtained for reactions carried out with pure xylitol, but in this case by‐products, such as di‐ and tri‐esters isomers were formed, which required a multi‐step purification process. For the systems with protected xylitol, conversions of 86%, 58% and 24% were achieved using oleic, lauric and butyric acids, respectively. The structures of the monoesters were confirmed by ¹³C‐ and ¹H‐NMR and microanalysis. CONCLUSION: The chemoenzymatic synthesis of xylitol monoesters avoided laborious downstream processing when compared with reactions performed with pure xylitol. Monoesters production from protected xylitol was shown to be a practical, economical, and clean route for this process, allowing a simple separation, because there are no other products formed besides xylitol monoesters and residual xylitol. Copyright © 2009 Society of Chemical Industry     

Participation of free fatty acids in the oxidation of purified soybean oil during microwave heating

Effects of 0 to 1.0% levels of caprylic, capric, lauric, myristic, palmitic or stearic acid on the oxidative stability of purified soybean oil were investigated under microwave heating conditions. A prooxidative effect of the fatty acids introduced into the systems was established. The extent of this effect depended on the acyl chin and levels of added fatty acids. During microwave heating, the oxidative rate of purified soybean oil by the fatty acids was rapid compared to the addition of their corresponding hydrocarbons; the shorter the chainlength and the higher the levels of fatty acids, the more accelerated was the thermal oxidation in the oil. The results are explained on the basis of the catalytic effect of the carboxylic group on the formation of free radicals by the decomposition of hydroperoxides. Therefore, particular attention should be paid to the free fatty acid content, which affects the oxidative stability of purified soybean oil.     

Biodiesel from rapeseed oil,methanol and KOH. 3. Analysis of composition of actual reaction mixture

Detailed analysis is described of the samples taken after suitable reaction times from the actual reaction mixture during the production of biodiesel fuel using methanolysis of rapeseed oil catalyzed by KOH. Three methods for stoppage of reaction (neutralisation of catalyst, dilution by two suitable solvents) in the sample are used. The contents of mono‐, di‐ and triacylglycerols, methylesters of fatty acids (biodiesel) and potassium salts of fatty acids of rapeseed oil, glycerol (by HPLC method), basicity (by potentiometric titration) and water (by GC and Karl‐Fischer method) in the samples are determined. An example of these determinations is described.     

Influence of fatty acids on the tocopherol stability in vegetable oils during microwave heating

Effects of 0, 0.05, 0.25, 0.50 and 1.0% levels of fatty acids (caproic, caprylic, capric and lauric) or hydrocarbons (decane and dodecane) on tocopherol stability in vegetable oils during microwave heating were determined by measuring tocopherol losses and carbonyl and anisidine values. The fatty acids showed similar prooxidant activities toward tocopherols in purified vegetable, oils when heated in a microwave oven. However, decane or dodecane, which had the same number of carbons as capric or lauric acid but no carboxylic group, did not show prooxidant activity. The shorter the chainlength and the higher the level of fatty acids, the greater was the reduction of tocopherols in the oils. The addition of low-molecular weight fatty acids resulted in greater acceleration in the oxidation of to pay attention to these free fatty acids produced in the oils when heated in a microwave oven.     

Indian stillingia oil and tallow

Summary The stillingia oil and tallow from the seeds ofSapium sebiferum Roxb., have been studied for their component fatty acids and component glycerides. The fatty acids composition was determined by Twitchell's lead-salt-alcohol method followed by systematic fractionation of the methyl esters under high vacuum. The glyceridic composition of the stillingia oil has been examined by permanganate-oxidation and bromination methods whereas the composition of the glycerides of the stillingia tallow was arrived at by using the low-temperature crystallization technique. The component fatty acids of the stillingia oil have been found to consist of caprylic (1.5%), capric (1.0%), myristic (0.97%), palmitic (2.8%), stearic (1.0%), oleic (9.4%), linoleic (53.4%), and linolenic (30.0%); the latter two are the major constituents. The glycerides of the oil were found to consist of disaturated-mono-linolein (7.9%), mono-saturated-dilinolein (7.9%), mono-oleo-di-linolein (6.1%), monolinoleno-di-linolein (45.7%), mono-linoleo-di-linolenin (10.7%), mono-oleo-di-linolenin (3.3%), and oleo-linoleo-linolenin (18.4%). The fatty acids composition of the stillingia tallow was found to be lauric (0.3%), myristic (4.2%), palmitic (62.3%), stearic (5.9%), and oleic (27.4%). The component glycerides were found to be trisaturated (31.2%), disaturated monounsaturated (64.0%) and monsaturated, diunsaturated (4.8%).     

Effect of lipid type on water‐in‐oil‐emulsions stabilized by phosphatidylcholine‐depleted lecithin and polyglycerol polyricinoleate

Water‐in‐oil (W/O, 30:70) emulsions were prepared with phosphatidylcholine‐depleted lecithin [PC/(PI,PE) = 0.16] or polyglycerol polyricinoleate (PGPR) as emulsifying agents by means of pressure homogenization. The effect of lipid type (medium‐chain triacylglycerols, sunflower, olive, butter oil, or MCT‐oil/vegetable fat blends) was investigated in relation to particle size distribution, coalescence stability and the sedimentation of the water droplets. A significant correlation (p <0.05) was observed between the interfacial pressure caused by the addition of lecithin to the pure lipids and the specific surface area of the emulsion droplets (r_s = 0.700), and between the viscosity of the lipids used as the continuous phase (reflecting the fatty acid composition) and the specific surface area of the emulsion droplets (r_s = 0.8459) on the other hand. Blends of vegetable fat and MCT‐oil led to reduced coalescence stability due to the attachment of fat crystals to the emulsion droplets. Lecithin‐stabilized W/O emulsions showed significantly higher viscosities compared to those stabilized with PGPR. It was possible to adjust the rheological properties of lecithin‐stabilized emulsions by varying the lipid phase.     

Rubber swell as a function of fatty acid ester chain length

A study was made of the relationship between the structure of some fatty acid esters of varying chain length and their swelling effect on standard nitrile rubber samples. The esters evaluated were: methyl esters of caprylic, capric, lauric, myristic, palmitic and isostearic acids;n-butyl, isobutyl,n-octyl, octadecyl, “tallow” and 2,2-dimethyl-1,3-propanediol esters of lauric acid and tetradecyl acetate. Federal test methods for aircraft turbine lubricants were used for the evaluations. In the esters the swelling was higher with type L rubber than with type H. The lower the equivalent weight of the ester, the higher the swell with both types of rubber. Branching in the alcohol moiety lowered the swell. Deswelling (desorption) in air of the swelled samples was also investigated. Methyl myristate, methyl palmitate and the long chain laurate esters meet MIL-L-23699 military specifications for type H rubbers. In type L rubbers the swelling is too high to meet specifications. Presented at the AOCS Meeting, Houston, Texas, May 1971. E. Market. Nutr. Res. Div. ARS, USDA.     

Enzymatic synthesis of medium‐chain triacylglycerols by alcoholysis and interesterification of copra oil using a crude papain lipase preparation

We have examined the possibility of producing analogs of medium‐chain triglycerides (MCT) from copra oil, i.e. a triacylglycerol mixture with a high content of medium‐chain fatty acid moieties (C₆–C₁₀). A two‐step enzymatic process was used in which copra triacylglycerols were first split with papain lipase by alcoholysis with an alkyl alcohol and then subjected to interesterification with the alkyl esters recovered using papain lipase. Effects of temperature, water activity content, substrate ratio, biocatalyst amount, and alcohol chain length were also investigated. On the one hand, the sn‐3 stereoselectivity of the lipase in the alcoholysis of copra oil with butanol has permitted a direct enrichment of caproic, caprylic and capric moieties in the synthesized butyl esters. Thus, in the batch reactor, the reaction led to about 31% conversion of the oil after 24 h, and the content of C₆–C₁₀ acids in the synthesized esters increased from about 16% in the starting oil to almost 42%. A similar enzymatic alcoholysis in a packed‐bed column bioreactor gave 31% conversion of the oil after 120 min of reactor residence time. The reaction was also very selective because the C₆–C₁₀ fatty acyl groups represented about half of the newly formed butyl esters, whereas they accounted for only 16% of total fatty acids in the starting oil. On the other hand, the transesterification of the alkyl esters recovered (highly enriched in C₆–C₁₀ fatty acyl groups) with native copra oil directly led to an increase in the content of MCT in the oil, from 18 mol‐% at the beginning of the reaction to 61 mol‐% of MCT after a time period of 72 h in the batch reactor.     

Sterilization and extraction of palm oil from screw pressed palm fruit fiber using supercritical carbon dioxide

The supercritical carbon dioxide (SC-CO₂) was successfully used in the complete sterilization as well as simultaneous extraction of oil from screw pressed palm fruit fiber. The studies were conducted at different temperatures (40, 50, 70 °C) and pressures (13.7, 20.7 MPa) for 60 min of extraction period. The bacteria, gram negative (Bacillus), present in the sample was completely killed at 20.7 MPa and 50 °C. Palmitic and oleic acid were found to be the major fatty acids in extracted oil. More saturated fatty acid were extracted at 50 °C and lower operating pressure (13.7 MPa). The unsaturated components, such as linoleic and oleic acids were extracted at higher pressures of 27.6 and 34.5 MPa, respectively. The fatty acids composition of the extracted oil analyzed using gas chromatography–mass spectrometry (GC/MS) includes caprylic, capric, lauric, myristic, palmitic, margaric, stearic, oleic, linoleic, linolenic, arachidic and gadoleic acids.     

How can we genetically engineer oilseed crops to produce high levels of medium‐chain fatty acids?

The end products of fatty acid synthase activities are usually 16‐ and 18‐carbon fatty acids. There are however, several plant species that store 8‐ to 14‐carbon (medium‐chain) fatty acids in their oil seeds. Among the medium‐chain fatty acids (MCFA), caprylic (8:0) and capric (10:0) are minor components of coconut oil, which are used in many industrial, nutritional and pharmaceutical products. Engineering crop plants such as Brassica could provide an economical source of these oils. During the last decade many laboratories have identified, cloned and characterized both the biosynthetic and catabolic enzymes regulating the composition and levels of these unusual fatty acids in seed oil. Among the biosynthetic enzymes thioesterases (TE), β‐ketoacyl‐ACP synthases (KAS) and acyltransferases are best characterized. In fact several independent investigators have shown that combined expression of the medium‐chain specific enzymes, specifically, TE, KAS and lysophosphatidic acid acyltransferase (LPAAT) results in the production of significant levels of MCFA in seed that otherwise do not accumulate any medium‐chain fatty acid. However, any additional increase in the levels of MCFA in transgenic seeds will require further detailed studies, such as possible induction of the medium‐chain specific enzymes in β‐oxidation and the glyoxylate pathways. To examine such a possibility, a number of genes involved in the β‐oxidation cycle among them a novel enzyme now designated as ACX3, a medium‐chain specific acyl‐CoA‐oxidase, has also been cloned. This article is an attempt to summarize our current knowledge and the present status of engineering oilseed crops for production of medium‐chain fatty acids.