Identification of minor cyclic fatty acids in fractionated tall oil

The structure of several minor cyclic fatty acids present in Finnish tall oil fatty acids are elucidated by gas chromatography-mass spectrometry. The origin and mechanism of formation of these cyclic fatty acids are discussed. The cyclic fatty acids identified in tall oil fatty acids are: 4-(5-pentyl-3a,4,7,7a-tetrahydro-4-indanyl)butanoic acid,ω-(o-alkylphenyl)alkanoic acid, 2,6-dimethyl-9-(3-isopropylphenyl)-6-nonenoic acid, 4-(5-pentyl-4-indanyl)butanoic acid, and 4-(2-hexyl-1,2,4a,5,6,7,8,8a-octahydro-1-naphthyl)butanoic acid. In addition, three different branched or cyclic unsaturated C₁₉ fatty acids are reported to be present in tall oil.     

Impact of Free Fatty Acids and Phospholipids on Reverse Micelles Formation and Lipid Oxidation in Bulk Oil

Association colloids such as phospholipid reverse micelles could increase the rate of lipid oxidation in bulk oils. In addition to phospholipids, other surface active minor components in commercial oils such as free fatty acids may impact lipid oxidation rates and the physical properties of reverse micelles. In this study, the effects of free fatty acids on changes in the critical micelle concentration (CMC) of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) in stripped corn oil (SCO) were determined by using the 7,7,8,8-tetracyanoquinodimethane solubilization technique. Different free fatty acids including myristoleic, oleic, elaidic, linoleic and eicosenoic were added at 0.5 % by wt along with the DOPC into the bulk oils. There was no significant effect of free fatty acids with different chain length, configuration and number of double bonds on the CMC value for DOPC in bulk oil. However, increasing concentrations of oleic acid (0.5 to 5 % by wt) caused the CMC value for DOPC in bulk oils to increase from 400 to 1,000 μmol/kg oil. Physical properties of DOPC reverse micelles in the presence of free fatty acids in bulk oils were also investigated by the small angle X-ray scattering technique. Results showed that free fatty acids could impact on the reverse micelle structure of DOPC in bulk oils. Moreover, free fatty acid decreased pH inside reverse micelle as confirmed by the NMR studies. The oxidation studies done by monitoring the lipid hydroperoxide and hexanal formation revealed that free fatty acids exhibited pro-oxidative activity in the presence and absence of DOPC. Different types of free fatty acids had similar pro-oxidative activity in bulk oil.     

GC-MS characterization (Chemical lonization and electron impact modes) of the methyl esters and oxazoline derivatives of cyclopropenoid fatty acids 1

The CI-(CH₄) mass spectra of the methyl esters and the EI mass spectra of the oxazoline derivatives of three cyclopropenoid fatty acids (malvalic, sterculic and α- hydroxy-sterculic acid) from the seed oil ofPachira aquatica were found to be useful for structure elucidation of such compounds. Furthermore, some hitherto unknown minor fatty acids were identified and the nuclear magnetic resonance data of the oil and α-hydroxysterculic acid methyl ester are presented.     

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.     

Isolation of a Series of Fatty Acid Components of Ongokea gore Seed (Isano) Oil and their Detailed Structural Analysis

The total oil production capacity of isano oil is estimated at about 10,000 tons annually. Previous studies of this oil revealed that it is rich in fatty acids including a conjugated diyne moiety. This makes isano oil an excellent candidate for sustainable applications development. However, only a few of its fatty acids have been isolated and identified so far. In this study, we have reinvestigated this oil by characterizing its physicochemical properties and isolating several of its fatty acids as ethyl esters for their detailed structural analysis and identification. Six ethyl esters of fatty acids constituting isanic oil were isolated by flash column chromatography and semipreparative HPLC. The detailed structural analysis of these fatty acid esters by infrared, high resolution, mass spectroscopy, and nuclear magnetic resonance (1‐D and 2‐D) allowed determining unequivocally their chemical structure. The main fatty acid component of the oil (35.7 %) was identified as isanic acid. Four minor acids were found to possess also two conjugated triple bonds, while the sixth fatty acid does not contain carbon–carbon triple bonds nor double bonds but possessed a cis epoxide function. Results obtained in this study are currently being used to explore potential applications of isano oil.     

Peanut oil: Compositional data

The major fatty acids of peanut oil acylglycerols are palmitic (C16:0), oleic (C18:1), and linoleic (C18:2) acids, and only a trace amount of linolenic fatty acid (C18:3) is present. Thus they have a very convenient oxidative stability and have been considered premium cooking and frying oils. This paper provides information about compositional data of peanut oil taking into account major (triacylglycerols and their fatty acids) and minor (free fatty acids, diacylglycerols, phospholipids, sterols, tocopherols, tocotrienols, triterpenic and aliphatic alcohols, waxes, pigments, phenolic compounds, volatiles, and metals) compounds. Moreover, the influence of genotype, seed maturity, climatic conditions, and growth location on peanut oil chemical composition is considered in the present report. In addition, peanut oils from wild species found in South America as well as from peanut lines developed through conventional breeding are also compared.     

Determination of free fatty acids and diacylglycerols in native vegetable oils

The analysis of free fatty acids (FFA) and diacylglycerols (DG) by GLC may be used to detect the deacidification of oils. Free fatty acids are removed from the oil during neutralization or physical refining, while the corresponding DG remain in the oil. This will change the ratio of FFA to DG. For analysis, oils with tricaprin as internal standard are silylated and injected on-column onto a short high-temperature capillary column. Extracted oils showed higher amounts of FFA and DG than pressed oils from the same batch of seeds. There are only minor changes in the ratio of FFA to DG according to the yield of pressing or due to washing the oil.     

Cod liver oil fatty acids as secondary reference standards in the GLC of polyunsaturated fatty acids of animal origin: analysis of a dermal oil of the atlantic leatherback turtle

The use of the esters of whole cod liver oil fatty acids as secondary standards in the GLC identification of animal polyunsaturated fatty acids is feasible. This technique is exemplified by an analysis on several polyester substrates of the component fatty acids of a somewhat unusual marine-type oil from the Atlantic Leatherback turtleDermochelys coriacea coriacea (Linné), with provisional identifications of minor components through the linear log plot and separation factor procedures.     

Surface-Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

The paper reports the investigation of tribochemically formed boundary films of canola oils using surface-enhanced Raman spectroscopy. This is the first time that metallic surfaces lubricated by plant oils have been studied using this technique. The results of this work provided strong evidence that fatty acids were liberated from the triglyceride structure during sliding to form a fatty acid soap layer on the silver surface. The study also revealed that the fatty acid chains of the unrefined canola oil were more disordered and most likely in a gauche conformation, while that of the refined canola oil were tightly packed and oriented perpendicular to the surface. It is believed that the greater presence of polar minor components in the unrefined oil, such as phospholipids, interfered with the ability of free fatty acids to form a tightly packed monolayer on the silver surface.     

Lipase‐catalyzed production of biodiesel from rice bran oil

Biodiesel has attracted considerable attention as an alternative fuel during the past decades. The main hurdle to the commercialization of biodiesel is the cost of the raw material. Use of an inexpensive raw material such as rice bran oil is an attractive option to lower the cost of biodiesel. Two commercially available immobilized lipases, Novozym 435 and IM 60, were employed as catalyst for the reaction of rice bran oil and methanol. Novozym 435 was found to be more effective in catalyzing the methanolysis of rice bran oil. Methanolysis of refined rice bran oil and fatty acids (derived from rice bran oil) catalyzed by Novozym 435 (5% based on oil weight) can reach a conversion of over 98% in 6 h and 1 h, respectively. Methanolysis of rice bran oil with a free fatty acid content higher than 18% resulted in lower conversions (<68%). A two‐step lipase‐catalyzed methanolysis of rice bran oil was developed for the efficient conversion of both free fatty acid and acylglycerides into fatty acid methyl ester. More than 98% conversion can be obtained in 4–6 h depending on the relative proportion of free fatty acid and acylglycerides in the rice bran oil. Inactivation of lipase by phospholipids and other minor components was observed during the methanolysis of crude rice bran oil. Simultaneous dewaxing/degumming proved to be efficient in removing phospholipids and other minor components that inhibit lipase activity from crude rice bran oil. Copyright © 2005 Society of Chemical Industry     

Study of color stability of tall oil fatty acids through isolation and characterization of minor constituents

Minor constituents in high quality tall oil fatty acids have been isolated successfully by liquid column chromatography, using silicic acid as the adsorbent. The minor constituents contained two types of compounds: those which were noneffective and those which were effective in causing the darkening of tall oil fatty acids during heating. The former consisted oftrans-3,5-dimethoxystilbene and rosin acids. The latter was separated into numerous fractions by the combination of chemical methods, silicic acid column chromatography, and low temperature fractional crystallization. The fractions were characterized by functional group analyses, chemical reactions, and UV and IR spectrometric methods. Most of the fractions contained two-three times as much oxygen in the molecule as the original sample and were highly oxidized fatty acids. They had mol wt ranging 300–551 and contained double bonds, carbonyl, ester, peroxide, and hydroxyl groups. The effect of these minor constituents upon the color stability of tall oil fatty acids during heating was postulated as being due to the hydroxyl groups located in the α-position to the double bond in the molecule.     

Identification of the Unsaturated Heptadecyl Fatty Acids in the Seed Oils of <Emphasis Type="Italic">Thespesia populnea</Emphasis> and <Emphasis Type="Italic">Gossypium hirsutum</Emphasis>

The fatty acid composition of the seed oils of Thespesia populnea and cotton variety SG-747 (Gossypium hirsutum) were studied to identity their 17-carbon fatty acids. With a combination of chemical derivatization, gas chromatography, and mass spectrometry, 8-heptadecenoic acid, 9-heptadecenoic acid, and 8,11-heptadecadienoic acids were identified in both oils. Additionally, traces of 10-heptadecenoic acid were identified in the T. populnea oil. Although these odd-carbon number fatty acids are present in only minor amounts in cottonseed oil, they make up about ~2 % of the fatty acids in T. populnea seed oil. The identification of these acids indicates that fatty acid α-oxidation is not restricted to cyclopropene fatty acids in these plants, but also occurs with unsaturated fatty acids. Combined with malvalic acid (generally accepted as being formed by α-oxidation of sterculic acid), ~7 % of the fatty acids in T. populnea seed have under gone α-oxidization. The results should help clarify the composition of T. populnea seed oil, which has been reported inconsistently in the literature.     

油酸的精制研究

油酸酰胺是一种很好的塑料添加剂 ,可用作塑料加工成型时的脱膜剂、润滑剂。油酸的原料来源很广 ,牛油、羊油、猪油等动物油油脂以及大豆油、花生油、棕榈油等植物油脂中都含有大量的油酸。由于油酸的来源和生产方法多种多样 ,因此其所含的脂肪酸种类及含量都不尽相同。除油酸外 ,还有亚油酸、亚麻酸等高不饱和脂肪酸。针对油酸中因含有大量的多不饱和组分如亚油酸、亚麻酸而容易产生氧化泛黄的问题 ,采取了尿素络合法对原料油酸进行精制 ,以减少原料中亚油酸、亚麻酸组分的含量。经气相色谱验证 ,产品达到了应用指标 ,提高了产品的抗氧性。     

DC-Trennung von Ricinusölfettsäure-Partialglyceriden

Thin-Layer Chromatographic Separation of Partial Glycerides of Castor Oil Fatty Acids Partial glycerides of castor oil fatty acids and hydrogenated castor oil fatty acids were prepared by esterification or glycerolysis and fractionated, together with commercial products, by TLC (especially by two-dimensional technique) on silicagel 60 precoated plates. By comparison of the two-dimensional chromatograms of the partial esters of castor oil fatty acids with synthetic standards, such as partial glycerides of ricinoleic, di- and tri-ricinoleic acids, estolides of castor oil fatty acids esterified to partial glycerides, and partial esters of castor oil fatty acids with 1,3-propanediol, the substances that could be identified were partial glycerides of ricinoleic, diricinoleic and triricinoleic and tetraricinoleic acids as well as partial glycerides, which contained, in addition to ricinoleic, diricinoleic and triricinoleic acids, fatty acids without hydroxyl groups as terminal estolide chain. The TLC enables an insight into the complex character of the glyceride composition of partial glycerides of castor oil fatty acids.     

Free fatty acid fractions from some vegetable oils exhibit reduced survival time-shortening activity in stroke-prone spontaneously hypertensive rats

Previously, we demonstrated that several vegetable oils that included low-erucic rapeseed oil markedly shortened the survival time (by ∼40%) of stroke-prone spontaneously hypertensive (SHRSP) rats as compared with perilla oil, soybean oil, and fish oil. We considered that a factor other than fatty acids is toxic to SHRSP rats, because the survival time-shortening activity could not be accounted for by the fatty acid compositions of these oils. In fact, a free fatty acid (FFA) fraction derived from lipase-treated rapeseed oil was found to be essentially devoid of such activity. A high-oleate safflower oil/safflower oil/perilla oil mixture exhibited a survival time-shortening activity comparable to that of rapeseed oil, but the activity of this mixed oil was also reduced by lipase treatment. A partially hydrogenated soybean oil shortened the survival time by ∼40%, but a FFA fraction derived from lipase-treated partially hydrogenated soybean oil shortened it by 13% compared with soybean oil. Fatty acid compositions of the rapeseed oil and a FFA fraction derived from lipase-treated rapeseed oil were similar, but those of hepatic phospholipids of rats fed the oil and FFA were slightly but significantly different. These results support the interpretation that the survival time-shortening activity exhibited by some vegetable oils is due to minor components other than fatty acids, and that an active component(s) were produced in or contaminated soybean oil during the partial hydrogenation processes.     

Hydrogenolysis products of the minor fatty acids fromEuphoria longana seed oil

The behavior of shorter-chain cyclopropane fatty acid components ofEuphoria longana seed oil and some other minor components during hydrogenolysis has been studied by open-tubular gas liquid chromatography on butanediolsuccinate polyester and Apiezon L substrates. The retention data and degree of resolution of the pairs of monomethylbranched fatty acids resulting from the hydrogenolysis of cyclopropane rings are used to indicate the positions of the latter in a series of fatty acids as ω9 relative to the terminal methyl group. An instance of possible isomerization of a cyclopropene fatty acid has been detected. The probable positions of monoethylenic unsaturation in fatty acids are discussed.     

Fatty Acid Profile of Kenaf Seed Oil

The fatty acid profile of kenaf (Hibiscus cannabinus L.) seed oil has been the subject of several previous reports in the literature. These reports vary considerably regarding the presence and amounts of specific fatty acids, notably (12,13-epoxy-9(Z)-octadecenoic (epoxyoleic) acid, but also cyclic (cyclopropene and cyclopropane) fatty acids. To clarify this matter, two kenaf seed oils (from the Cubano and Dowling varieties of kenaf) were investigated regarding their fatty acid profiles. Both contain epoxyoleic acid, the Cubano sample around 2 % and the Dowling sample 5-6 % depending on processing. The cyclic fatty acids malvalic and dihydrosterculic were identified in amounts around 1 %. Trace amounts of sterculic acid were observed as were minor amounts of C17:1 fatty acids. The results are discussed in the context of the fatty acid profiles of other hibiscus seed oils.     

Impacts of roasting oily seeds and nuts on their extracted oils

During industrial processing of seeds and nuts to produce edible oils, roasting is often applied before oil extraction. Moreover, seeds and nuts are generally consumed as snack food after appropriate roasting. These processes affect both the seeds and their extracted oils in many ways. Beside changes in macronutrients such as protein denaturation/degradation, oil oxidation, sugar pyrolysis and Maillard reactions, minor constituents such as fatty acids, sterols, phenolic compounds and tocols are also affected by roasting. On the other hand, studies have shown that antioxidant capacity of the roasted seeds and oxidative stability of the extracted oil could be greater than that of the unroasted counterpart. These improvements are attributed to the formation of Maillard reaction products, inactivation of oil degrading enzymes and facilitation of phytochemical extraction as a result of roasting.     

Current advances in sunflower oil and its applications

The fatty acid and triacylglycerol composition of a vegetable oil determine its physical, chemical and nutritional properties. The applications of a specific oil depend mainly on its fatty acid composition and the way in which fatty acids are arranged in the glycerol backbone. Minor components, e. g. tocopherols, also modify oil properties such as thermo‐oxidative resistance. Sunflower seed commodity oils predominantly contain linoleic and oleic fatty acids with lower content of palmitic and stearic acids. High‐oleic sunflower oil, which can be considered as a commodity oil, has oleic acid up to around 90%. Additionally, new sunflower varieties with different fatty acids and tocopherols compositions have been selected. Due to these modifications sunflower oils possess new properties and are better adapted for direct home consumption, for the food industry, and for non‐food applications such as biolubricants and biodiesel production.     

Effects of refining on chemical and physical properties of palm oil products

Some chemical changes in the composition and physical properties of palm oil products are discussed. The effects of bleaching and deodorization on oxidative properties and possible isomerization and interesterification of the fatty acids were indicated from laboratory refining experiments. Investigation of commercial samples of refined palm oil products showed that the conjugated dienes and trienes formed are minimal, indicating the use of good quality raw materials and mild processing conditions. Very little isomerization occurred in commercial refined products as indicated from the level oftrans acids, and changes in the POP to PPO triglycerides due to possible interesterification were insignificant. Changes in physical properties were inevitable due to the removal of free fatty acids and diglycerides and to minor impurities.