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.     

The triglyceride composition,structure, and presence of estolides in the oils ofLesquerella and related species

Members of the genusLesquerella, native to North America, have oils containing large amounts of hydroxy fatty acids and are under investigation as potential new crops. The triglyceride structure of oils from twenty-fiveLesquerella species in the seed collection at our research center has been examined after being hydrolysis-catalyzed by reverse micellar-encapsulated lipase and alcoholysis-catalyzed by immobilized lipase. These reactions, when coupled with supercritical-fluid chromatographic analysis, provide a powerful, labor-saving method for oil triglyceride analysis. A comprehensive analysis of overall fatty acid composition of these oils has been conducted as well.Lesquerella oils (along with oils from two other Brassicaceae:Physaria floribunda andHeliophilia amplexicaulis) have been grouped into five categories: densipolic acid-rich (Class I); auricolic acid-rich (Class II); lesquerolic acid-rich (Class III); an oil containing a mixture of hydroxy acids (Class IV); and lesquerolic and erucic acid-rich (Class V). The majority of Class I and II triglycerides contain one or two monoestolides at the 1- and 3-glycerol positions and a C₁₈ polyunsaturated acyl group at the 2-position. Most Class III and IV oil triglycerides contain one or two hydroxy acids at the 1- and 3-positions and C₁₈ unsaturated acid at the 2-position. A few of the Class III oils have trace amounts of estolides. The Class V oil triglycerides are mostly pentaacyl triglycerides and contain monestolide and small amounts of diestolide. Our triglyceride structure assignments were supported by¹H nuclear magnetic resonance data and mass balances.     

Triacylglycerols and regiospecific fatty acid analyses of philippine seed oils

Three Philippine seed oils, namely coconut (Cocos nucifera Linn.), pilinut (Canarium ovatum Engl.), and cashew (Anacardium occidentale Linn.), which were selected for their local abundance and availability, were examined for their triacylglycerol profiles and fatty acid compositions. Triacylglycerol molecular species in terms of carbon number and partition number were determined by gas chromatography and liquid chromatography, respectively. The distribution of fatty acids in the primary and secondary positions of the glycerol backbones for the three oils were examined by regiospecific analysis by using pancreatic lipase. Coconut oil had high concentrations of lauric and myristic acids, while the other two oils did not have such fatty acids. Lauric acid in coconut oil and linoleic acid in pilinut oil were distributed mainly in the primary positions (sn-1,3) of the glycerol backbone. Trilaurin and dioleylpalmitoylglycerol were the major triglycerides in coconut and pilinut oils, respectively.     

Utilization of acid oils in making valuable fatty products by microbial lipase technology

Microbial lipase-catalyzed hydrolysis, esterification, and alcoholysis reactions were carried out on acid oils of commerce such as coconut, soybean, mustard, sunflower, and rice bran for the purpose of making fatty acids and various monohydric alcohol esters of fatty acids of the acid oils. Neutral glycerides of the acid oils were hydrolyzed byCanadida cylindracea lipase almost completely within 48 h. Acid oils were converted into fatty acid esters of short- and long-chain alcohols like C₄, C₈, C₁₀, C₁₂, C₁₆, and C₁₈ in high yields by simultaneous esterification and alcoholysis reactions withMucor miehei lipase as catalyst. Acid oils of commerce can be utilized as raw materials in making fatty acids and fatty acid esters using lipase-catalyzed methodologies.     

Utilization of acid oils in making surface-active compounds by lipase-catalyzed hydrolysis and esterification reactions

Nonionic surface-active molecules were made from acid oils such as mustard, sunflower, rice bran, soybean, coconut, and polyethylene glycols (PEG) of varying molecular weights (200, 300, 400, 600), using processes based on lipasecatalyzed hydrolysis with Candida cylindracea lipase and esterification with Mucor miehei lipase. Both the PEG molecular weight and the acid oil influence the yield of ester. Molar concentration of reatants also influences the rate and yield of ester. Surface tension values of ester products reveal that maximal lowering of surface tension of water occurs in the case of PEG 600 and coconut acid oil ester. This work demonstrates an important technological advance in the synthesis of nonionic surfactants of the alkyl ethoxylate type from a variety of acid seed oils in high yields by using lipase technology involving first hydrolysis and then esterification with another lipase.     

Transesterification of brazilian vegetable oils with methanol over ion-exchange resins

The transesterification of several Brazilian vegetable oils with methanol was carried out at 60°C in the presence of several ion-exchange resins having different structures. The vegetable oils used were from Babassu coconut, corn, palm, palm kernel, and soybean. The effect of the methanol/oil mole ratio and the influences of the structure of the ion-exchange resin and the type of vegetable oil used on the catalytic activity of the ionexchange resins were investigated. The resins used were Amberlyst 15, Amberlyst 31, Amberlyst 35, and Amberlyst 36. Amberlyst 15 produced the best results for the transesterification of vegetable oils. The methyl ester yield is higher for palm kernel oil and Babassu coconut oil than for soybean oil, probably owing to their higher content of shorter-chain FA. Therefore, it was shown that the catalytic activity of the resin depends on the FA composition of the vegetable oil employed.     

Chemical survey and erucic acid content of commercial varieties of nasturtium,Tropaeolum majus L.

Nasturtium (Tropaeolum majus L.) oil contains the highest levels of erucic acid of known seed oils (75–80%). A significant portion of the acid is attached to the 2-position of the glycerol, and trierucin is a major component (ca. 50%) of the oil. Seeds from eleven varieties of commercially available garden nasturtium (T. majus) were screened for oil content, erucic acid levels and fatty acid distribution. Oil contents ranged fromca. 6 to 11%, and erucic acid levels in the oils ranged from 62 to 80%. One sample ofT. speciosum was also analyzed, and contained 28% oil, fatty acids from C₁₆ to C₂₈ and triglycerides up to C₇₂.     

Composition of oil

International trade in palm oil has increased considerably over the last ten years, and so too has the trade in processed palm oil products, especially palm fractions. It is important to establish reliable purity criteria for palm oil, not only because of the commercial need to verify oil authenticity, but also to comply with foodstuff labelling legislation in many countries. Palm kernel and coconut oils both contain about 47% lauric acid. This gives the oils close similarities in physical and chemical properties. The oils do differ, however, and it is important to be able to distinguish between them. Purity problems can arise as a result of commingling of oils with one another, or as a result of fractionation perhaps coupled with subsequent blending. A research program jointly funded by the (U.K.) Ministry of Agriculture, Fisheries and Foods, the Federation of Oils, Fats & Seeds Associations Ltd (FOSFA International), and the Leatherhead Food RA, was established to study purity characteristics of the major edible vegetable oils. Forty-seven samples of crude palm oil were obtained from reliable sources, often plantation managers, together with five samples of palm olein and eight samples of palm stearin. Fifty-four palm kernel and 23 coconut oils were obtained in the laboratory from seed samples of known geographical origins and authenticities. These oil samples were analyzed for fatty acid, triglyceride, sterol and tocopherol compositions; the melting properties were also determined, and in the case of palm oil the compositions of the acids at the triglyceride 2-positions were measured. Compositional ranges will be presented for the different geographical production areas in each case and related to existing data, e.g., of PORIM and Codex. An initial statistical analysis of the results has shown that a combination of values from the carbon number analysis differentiates palm kernel and coconut oils, and can be used to decide on the proportion of each in a blend. In the case of palm oil samples suspected to be contaminated with palm fractions, it was found useful to plot melting point against iodine value, and to compute the product of the C48 triglyceride content and the palmitic acid enrichment factor.     

Modifications of butter stearin by blending and interesterification for better utilization in edible fat products

This work primarily aims to further modify the stearin fractions, obtained from anhydrous milk fat, after fractionation by dry process and by solvent process using isopropanol, for extending their scope of utilization in edible fat products. Butter stearin fractions, on blending with liquid oils like sunflower oil and soybean oil in different proportions, offer nutritionally important fat products with enriched content of essential fatty acids like C_18∶2 and C_18∶3. The butter stearin fraction from isopropanol fractionation, when interesterified with individual liquid oils by Mucor miehei lipase as a catalyst, yields fat products having desirable properties in making melange spread fat products with reasonable content of polyunsaturated fatty acids and almost zero trans fatty acid content.     

Esterification of fatty acids byAspergillus flavus

Aspergillus flavus, grown on soybean oil fatty acids as the sole carbon source, produced triglycerides. While most of the triglycerides were intracellular, considerable amounts also were found extracellularly. The latter originated most likely from esterification of fatty acids by a cell-bound lipase. Although the fatty acids of these fungal triglycerides were the same as those of soybean oil fatty acids, polyunsaturated acid content was greater than expected from the added substrate. Part of a presentation of the American Oil Chemists' Society Annual Meeting in Phoenix, AZ, in May 1988.     

Spoilage of coconut oil purification and properties of a fungal lipase that attacks coconut oil

A lipase was isolated from a strain ofAspergillus flavus which attacked coconut kernel and oil with the liberation of free fatty acids. The enzyme was purified 109-fold by ammonium sulphate precipitation, diethyl aminoethyl-cellulose and Sephadex G-200 chromatography. The optimum pH of the enzyme reaction was 6.2. The action of the enzyme on pure triglycerides was studied. The triglycerides of the shorter chain fatty acids were more rapidly hydrolyzed, while hydrolysis of tristearin was not detected under the conditions of assay. K _m for trilaurin and trimyristin were 9.09×10⁻⁴ and 1.42×10⁻³ M, respectively. Para-chloromercuricbenzoate was an inhibitor. Thin layer chromatography and gas liquid chromatography of the esterified products of enzymatic hydrolysis of coconut oil showed the presence of oleate, palmitate, myristate, laurate, caprate, caproate and caprylate but not stearate, although stearate was present in coconut oil.     

Trans FA and solid fat contents of margarines marketed in Turkey

Trans FA (TFA), solid fat contents (SFC), and slip melting points of 12 different tub and stick margarines marketed in Turkey were examined in this study. No trans isomers were found in four margarines, which suggests they were formulated from interesterified or blended fats and oils. The products with no TFA generally had more short-chain saturated FA, which suggests coconut oil-based oil components. TFA content of the other 10 products varied from 7.7 to 37.8%. Compared to the products formulated in North America, Turkish margarines contain more TFA and have higher SFC.     

Studies in interesterification. II. Acidolysis of some vegetable oils with lauric acid

Acidolysis reactions of cottonseed oil, peanut oil, mahua oil (Madhuca latifolia), and palm oil with lauric acid were investigated with special reference to the influence of catalysts and the relative proportions of oil and lauric acid on the extent and type of fatty acids displaced from an oil. Catalysts such as sulfuric acid, zinc oxide, calcium oxide, magnesium oxide, aluminum oxide, and mercuric sulfate were used. The reaction generally was carried out by heating oil and lauric acid at 150C±2 for 3 hr. The reaction products were separated and then analyzed by UV spectrophotometry and GLC. Sulfuric acid was found to be the best catalyst with 1 part of oil and 1.2 parts of the displacing acid (lauric acid) for displacement of high-molecular-weight fatty acids from an oil by low-molecular-weight fatty acids. The nature of the displacement of fatty acids varied from oil to oil, depending on their compositions. It was further indicated that linoleic acid was displaced preferentially over oleic acid in an amount dependent on its initial content in an oil with a corresponding increase in saturated acids content. A broad similarity in displacement patterns, in general, was noted; the fatty acids above C₁₈ were not displaced as in the case of peanut oil. The results demonstrate the feasibility of introducing lauric acid in the vegetable oils for the production of interesting oils with vastly different physical and chemical properties.     

Low erucic acid canola oil does not induce heart triglyceride accumulation in neonatal pigs fed formula

Canola oil is not approved for use in infant formula largely because of concerns over possible accumulation of triglyceride in heart as a result of the small amounts of erucic acid (22∶1n−9) in the oil. Therefore, the concentration and composition of heart triglyceride were determined in piglets fed from birth for 10 (n=4–6) or 18 (n=6) d with formula containing about 50% energy fat as 100% canola oil (0.5% 22∶1n−9) or 100% soybean oil, or 26% canola oil or soy oil (blend) with palm, high-oleic sunflower and coconut oil, providing amounts of 16∶0 and 18∶1 closer to milk, or a mix of soy, high-oleic sunflower and flaxseed oils with C₁₆ and C₁₈ fatty acids similar to canola oil but without 22∶1. Biochemical analysis found no differences in heart triglyceride concentrations among the groups at 10 or 18 d. Assessment of heart triglycerides using Oil Red O staining in select treatments confirmed no differences between 10-d-old piglets fed formula with 100% canola oil (n=4), 100% soy oil (n=4), or the soy oil blend (n=2). Levels of 22∶1n−9 in heart triglyceride and phospholipid, however, were higher (P<0.01) in piglets fed 100% canola oil or the canola oil blend, with higher levels found in triglycerides compared with phospholipids. The modest accumulation of 22∶1n−9 associated with feeding canola oil was not associated with biochemical evidence of heart triglyceride accumulation at 10 and 18 d.     

Correlating chemical structure and physical properties of vegetable oil esters

The influence of FA ester chemical structures on the rheology and crystallization temperature of those compounds was evaluated using methyl, n-butyl, n-octyl, and 2-ethyl-1-hexyl FA esters with different chain lengths and different degrees of unsaturation. The rheological properties were analyzed in a high-precision rheometer at various temperatures, and the crystallization temperatures were determined by DSC. Esters produced from the esterification of pure FA and from the transesterification of vegetable oils (i.e., soybean, corn, linseed, and babassu coconut oils) were evaluated. The length of the FA chain was shown to have a marked influence on the viscosity and crystallization temperature of the systems, whereas branching affected only the crystallization temperature to a significant extent. The viscosity and crystallization temperature of the systems were also influenced by the degree of unsaturation. One double bond was shown to increase viscosity, whereas two or three double bonds caused a decrease in the viscosity of the systems. Unsaturation lowered the crystallization temperature in all cases, regardless of the number of double bonds. From all the oils studied, methyl esters from babassu coconut oil presented the lowest crystallization temperatures.     

Feruloylated Products from Coconut Oil and Shea Butter

The synthesis of feruloylated coconut oil and feruloylated shea butter were demonstrated in 0.5-L scale, shaken, batch reactions. Ethyl ferulate and the vegetable oil/fat were combined in a 1.0:1.3 mol ratio in the presence of Candida antartica lipase B immobilized on an acrylic resin (Novozym 435) at 60 °C. The transesterification of ethyl ferulate with coconut oil and shea butter reached equilibrium conversions, after 22 days, of 63 and 70%, respectively, with the shea butter transesterifications producing a white precipitate not observed in the coconut oil transesterifications. The faster transesterification rates, equilibrium conversions and white precipitate were shown to result from di- and monoacylglycerols (DAG and MAG) present in the shea butter. The transesterification of ethyl ferulate and coconut oil was also tested in a continuous, enzymatic, packed-bed bioreactor using Novozym 435 at 60 °C to produce feruloylated coconut oil at rates of 0.5–0.9 kg/day over 4.5 months. The feruloylated coconut oil acylglycerol species were identified by LC–MS analysis of transesterification reactions of ethyl ferulate with medium chain triacylglycerol (TAG) standards, C8–C14. The feruloylated vegetable oils possessed an ultra violet (UV) absorbing λ _max 328 nm, making them good UVAII absorbers, as defined by the U.S. Food and Drug Administration. The feruloylated coconut oil possessed a 17.5% higher absorption capacity than feruloylated shea butter on a per weight basis. All the feruloylated vegetable oils possessed rapid antioxidant capacity (50% reduction of initial radical concentration <5 min) at the concentrations tested, 0.5–2.5 mM. Feruloylated coconut oil possessed chemical and physical characteristics that suggested it would be fungible for feruloylated soybean oil in current retail formulations.     

Sulfurized vegetable oil products as lubricant additives

Sulfurized products based on hog fat and its derivatives have extensive commercial use as additives for metalworking and industrial oils, but only relatively small quantities of vegetable oils find such application in North America. Products were made by sulfurization of soybean, sunflower, cottonseed, high erucic rapeseed, canola,Limnanthes (meadowfoam) and prime lard oils. Unlike products from the wax ester jojoba oil, the sulfurized vegetable triglycerides alone had physical properties generally undesirable for lubricant additives. When the oils were sulfurized in the presence of methyl lardate, however, the products had potential practical application. High-sulfur (active) products were made using a 50:50 ratio of triglyceride to methyl lardate, and low-sulfur (inactive) products were made using a 70:30 ratio. Compared to the other sulfurized vegetable triglyceride products,Limnanthes products showed the best solubility in high viscosity-index paraffinic oil. For solutions, measurements of extreme pressure, friction and wear were compared. Whereas products from jojoba were best, of the triglyceride group theLimnanthes-containing products generally gave the best performance. Although this oil had much promise, it is only in its early stage of commercial development. The other vegetable oils also have potential depending on cost and applications. However, overall competition with the well-established, usually lower-cost products from hog fat or greases would appear to be difficult.     

The effect of dietary vitamin E supply and a moderately oxidized oil on activities of hepatic lipogenic enzymes in rats

Diets rich in polyunsaturated fatty acids (PUFA) are well known to suppress hepatic lipogenic enzymes compared to fat-free diets or diets rich in saturated fatty acids. However, the mechanism underlying suppression of lipogenic enzymes is not quite clear. The present study was undertaken to investigate whether lipid peroxidation products are involved in suppression of lipogenic enzymes. Therefore, an experiment with growing male rats assigned to six groups over a period of 40 d was carried out. Rats received semisynthetic diets containing 9.5% coconut oil and 0.5% fresh soybean oil (coconut oil diet, peroxide value 5.1 meq O₂/kg oil), 10% fresh soybean oil (fresh soybean oil diet, peroxide value 0.5 meq O₂/kg oil), or 10% thermally treated soybean oil (oxidized soybean oil diet, peroxide value 74 meq O₂/kg oil). To modify the antioxidant state of the rats, we varied the vitamin E supply (11 and 511 mg α-tocopherol equivalents per kg of diet) according to a bi-factorial design. Food intake and body weight gain were not influenced by dietary fat and vitamin E supply. Activities of hepatic lipogenic enzymes were markedly influenced by the dietary fat. Feeding either fresh or oxidized soybean oil diets markedly reduced activities of fatty acid synthase, (FAS), acetyl CoA-carboxylase, (AcCX), glucose-6-phosphate dehydrogenase, (G6PDH), 6-phosphogluconate dehydrogenase, and ATP citrate lyase (ACL) relative to feeding the coconut oil diet. Moreover, feeding oxidized soybean oil slightly, but significantly, lowered activities of FAS, AcCX, and ACL compared to feeding fresh soybean oil. Activities of hepatic lipogenic enzymes were reflected by concentrations of triglycerides in liver and plasma. Rats fed the coconut oil diet had markedly higher triglyceride concentrations in liver and plasma than rats consuming fresh or oxidized soybean oil diets, and rats fed oxidized soybean oil had lower concentrations than rats fed fresh soybean oil. The vitamin E supply of the rats markedly influenced concentrations of thiobarbituric acid-reactive substances in liver, but it did not influence activities of hepatic lipogenic enzymes. Because the vitamin E supply had no effect, and ingestion of an oxidized oil had only a minor effect, on activities of hepatic lipogenic enzymes, it is strongly suggested that neither exogenous nor endogenous lipid peroxidation products play a significant role in the suppression of hepatic lipogenic enzymes by diets rich in PUFA. Therefore, we assumed that dietary PUFA themselves are involved in regulatio of hepatic lipogenic enzymes. Nevertheless, the study shows that ingestion of oxidized oils, regardless of the vitamin E supply, also affects hepatic lipogenesis, and hence influences triglyceride levels in liver and plasma.     

Determination of milk fat in chocolates by gas-liquid chromatography of triglycerides and fatty acids

The combination of two routine methods is proposed to determine the content of milk fat (MF) in chocolates, which is applicable even in the presence of lauric fats or others. The content of MF is obtained from the sum of C₄₀, C₄₂, and C₄₄ medium-chain triglycerides, determined by capillary gas-liquid chromatography (GLC). A new method, based on methyl esters of lauric acid and on minor acids situated between myristic and palmitic, is proposed. It enables detection and estimation of potential lauric fats, as well as the determination of the actual content of MF. The influence of other vegetable and animal fats is discussed. We analyzed 45 MF samples extracted from industrial milk powders and from pure or fractionated MF for chocolate manufacturing or pastry by GLC of triglycerides. We also analyzed by capillary GLC the methyl esters from 22 of those fats. Mixtures of these 22 MF samples with a cocoa butter also were used for chromatographic analyses of methyl esters and triglyceride. Results from the various analytical methods have been presented.     

Regiospecific analysis by ethanolysis of oil with immobilized <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase

A mixture of oil/ethanol (1∶3, w/w) was shaken at 30°C with 4% immobilized Candida antarctica lipase by weight of the reaction mixture. The reaction regiospecifically converted FA at the 1- and 3-positions to FA ethyl esters, and the lipase acted on C₁₄−C₂₄ FA to a similar degree. The content of 2-MAG reached a maximum after 4 h; the content was 28–29 mol% based on the total amount of FA in the reaction mixture at 59–69% ethanolysis. Only 2-MAG were present in the reaction mixture during the first 4 h, and 1(3)-MAG were detected after 7 h. After removal of ethanol from the 4-h reaction mixture by evaporation, 2-MAG were fractionated by silica gel column chromatography. The contents of FA in the 2-MAG obtained by ethanolysis of several oils coincided well with FA compositions at the 2-position, which was analyzed by Grignard degradation. It was shown that ethanolysis of oil with C. antarctica lipase can be applied to analysis of FA composition at the 2-position in TAG.