Influence of Temperature on the Fatty Acid Composition of the Oil From Sunflower Genotypes Grown in Tropical Regions

The influence of temperature on the fatty acid composition of the oils from conventional and high oleic sunflower genotypes grown in tropical regions was evaluated under various environmental conditions in Brazil (from 0° S to 23° S). The amounts of the oleic, linoleic, palmitic and stearic fatty acids from the sunflower oil were determined using gas chromatography (GC). The environment exhibited little influence on the amounts of oleic and linoleic fatty acids in high oleic genotypes of sunflower. In conventional genotypes, there was broad variation in the average amounts of these two fatty acids, mainly as a function of the minimum temperature. Depending on the temperature, especially during the maturation of the seeds, the amount of oleic acid in the oil of conventional sunflower genotypes could exceed 70 %. Higher temperatures led to average increases of up to 35 % for this fatty acid. Although the minimum temperature had the strongest effect on the fatty acid composition, locations at the same latitude with different minimum temperatures displayed similar values for both oleic acid and linoleic acid. Furthermore, minimum temperature had little influence on the amounts of palmitic and stearic fatty acids in the oil.     

Catalytic Deoxygenation of C18 Fatty Acids Over Mesoporous Pd/C Catalyst for Synthesis of Biofuels

Deoxygenation was systematically investigated using either stearic, oleic or linoleic acids as a feedstock at 300 °C under 1 vol% hydrogen in argon over a mesoporous Pd/C (Sibunit) catalyst producing one less carbon containing, diesel-like hydrocarbons. The results revealed that catalyst activity and selectivity increased with less unsaturated feedstock. The main products in the case of stearic acid were desired C17 hydrocarbons, whereas the amounts of C17 aromatic compounds increased in case of oleic and linoleic acids. Catalyst deactivation was relatively prominent in linoleic acid deoxygenation giving only 3% conversion of fatty acids in 330 min. The deactivation originated from the formation of C17 aromatic compounds and fatty acid dimers, which was confirmed by size exclusion chromatographic analysis. The latter compounds were formed via Diels?CAlder reaction.     

Separation of Oleic Acid from Fatty Acid Impurities

Abstract

A method of oleic acid purification is described. The method consists of the following five steps: 1) cooling of the sample to 4°C for a partial separation of palmitic acid by crystallization, 2) distillation at reduced pressure (0.8 mmHg) for removal of lauric and myristic acids, 3) crystallization of stearic and palmitic acids from acetone at -25°C, 4) separation of oleic acid from palmitoleic and linoleic acids by oleic acid crystallization from aqueous methanol solutions at ?10°C, 5) reduced pressure (0.5 mmHg) distillation of the resulting oleic acid sample for removal of water and methanol. By utilizing the procedure described above, a sample containing only 82% oleic acid was refined to a product containing 98.7–98.9% oleic acid.     

Fatty acid composition of oleaster pulp and pit oils

Fatty acid compositions of oleaster pulp and pit oils were determined by gas chromatography in 4 samples of different varieties. Pit oils were highly unsaturated, containing >90% linoleic, oleic, and linolenic acids, as well as traces of palmitoleic acid. Saturated fatty acids consisted of palmitic and stearic acids with traces of arachidic acid. Pulp oils showed fatty acid compositions entirely different from that of pit oils. They contained 9 saturated fatty acids, C₁₂ to C₂₄, some of them with high quantities, up to 34.9%, of the total fatty acids. Unsaturated fatty acids, mainly oleic and linoleic, with low quantities of palmitoleic and linolenic acids composed about one-third of the total fatty acids.     

The hydrolysis of fatty acid chlorides

Summary Fatty acid chlorides of octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, elaidic, and linoleic acids were hydrolyzed at 25° C, in water and the amounts of unchanged acid chlorides determined after different periods of reaction. Contrary to expectations, the chlorides of the longer chain fatty acids, palmitic and stearic, reacted at a more rapid rate than the chlorides of the shorter chain fatty acids. Lauryl chloride appears to be more resist-ant to hydrolysis than either the chlorides of the lower molecular weight octanoic and decanoic acids or the chlorides of the higher molecular weight myristic to stearic acids. The chlorides of the unsaturated acids, oleic, elaidic, and linoleic, are hydrolyzed less rapidly than stearyl chloride. However, elaidyl and myristyl chlorides exhibit the same relative rates of hydrolysis during the first two hours of reaction. Myristyl chloride hydrolyzes more rapidly than elaidyl chloride after the first two hours. The addition of either hydrochloric acid or free fatty acids to the reaction mixture was found to have no pronounced effect on the hydrolysis of the acid chlorides. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

The composition of the oil extracted from 14 different varieties ofAndropogon Sorghum var.Vulgaris

Summary Fourteen varieties ofAndropogon Sorghum var.vulgaris were subjected to fractional solvent extraction. An average yield of 0.32% wax and 2.76% of oil was obtained. The 14 sorghum grain oils varied from a light amber to green in color. They had an average refractive index of 1.4695 at 25° C. and contained 2.51% nonsaponifiable matter. The mixed fatty acids obtained from the oils had an average melting point of 28.9° C., a neutralization equivalent of 278.8, iodine value of 120.8, and thiocyanogen value of 81.5. The composition of the mixed fatty acids were calculated from the iodine and thiocyanogen values. The mixed fatty acids contained an average of 46.5% linoleic, 39.5% oleic, 7.8% palmitic, and 4.7% stearic acid. Financial support for this work was furnished by The Kansas Industrial Development Commission. Contribution No. 314 from The Department of Chemistry.     

Effects of Seed Roasting on Tocopherols,Carotenoids, and Oxidation in Mustard Seed Oil During Heating

Seed roasting is practiced in the mustard oil industry in some areas of the world, and can affect the physicochemical properties of the oil for further applications. This research studied the differences in oxidative stability, tocopherols, and carotenoids during heating at 160 °C between oil extracted from roasted mustard seeds and that from unroasted seeds. The content of free fatty acids, polar compounds (PC), and lutein were not significantly different between the roasted and unroasted seed oils before heating. The fatty acid compositions of both oils were also similar, with high amounts of erucic, linoleic, and oleic acids, moderate amounts of linolenic and eicosenoic acids, and low amounts of palmitic and stearic acids. However, the levels of tocopherols and conjugated dienoic acids (CDA) were higher in the roasted seed oil. Heating increased the content of CDA and PC in both oils, but decreased tocopherols and lutein. The rates of increase in CDA and PC and the degradation rates of tocopherols and lutein during heating were lower in the roasted than in the unroasted seed oil. Overall, the increased thermo-oxidative stability of the mustard oil by roasting the seeds before oil extraction was highly correlated with improved heat stabilities for both tocopherols and lutein.     

Sterols and Fatty Acids from the Neutral Lipids of Desilked Silkworm Pupae (Bombyx mori L.)

The desilked silkworm pupae (Bombyx mori L.) collected from Kollegala, Malavalli and Ramanagaram belt of Karnataka State (South India) were extracted with petroleum ether (60–80°C). The neutral lipids fraction was isolated and saponified. Saponifiable fraction was analysed for fatly acids and unsaponifiable fraction for sterols. The neutral lipids contain oleic, palmitic, palmitoleic, stearic, linoleic, I auric, myristic, C_13:0-, linolenic and arachidic acids. Cholesterol, β-sitosterol and a trace of campesterol are found to be present in unsaponifiable fractions.     

Comparison of Supercritical Fluid and Hexane Extraction Methods in Extracting Kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis>) Seed Oil Lipids

The objective of this study was to investigate and compare fatty acids, tocopherols and sterols of kenaf seed oil extracted by supercritical carbon dioxide and traditional solvent methods. Fatty acids, tocopherols and sterols were determined in the extracted oils as functions of the pressure (400 bar, 600 bar), temperature (40 °C, 80 °C) and CO₂ flow rate (25 g/min) using a 1-L extraction vessel. Gas chromatography was used to characterize fatty acids and sterols of the obtained oils while tocopherols were quantified by HPLC. No differences were found in the fatty acid compositions of the various oil extracts and the main components were found to be linoleic (38%), oleic (35%), palmitic (20%) and stearic acid (3%). Extraction of tocopherols using high pressure (600 bar/40 °C, 600 bar/80 °C) gave higher total tocopherols (88.20 and 85.57 mg/100 g oil, respectively) when compared with hexane extraction which gave yield of 62.38 mg/100 g oil. Extraction of kenaf seed oil using supercritical fluid extraction at high temperature (80 °C) gave higher amounts of sterols when compared with hexane extraction.     

Studies on Apocynacea Seed Oils

The fatty acid composition of three seed oils of Apocynaceae has been studied in this investigation. The seed oils of Apocynaceae were examined for their component acids and were found to contain the following acids: Rauwolfia serpentina, Benth, (wt.%) lauric 0.2 %, myristic 0.8 %, palmitic 17.7%, stearic 4.9 %, arachidic 0.9 %, behenic 0.6 %, oleic 34.4 %, and linoleic 40.5 %. Rauwolfia tetraphylla, Linn. syn. Rauwolfia canescens, Linn., Rauwolfia heterophylla, Roem and Schult, (wt.%) lauric 0.9 %, myristic 3.4 %, palmitic 25.7 %, stearic 10.3%, arachidic 1.6%, behenic 1.4%, oleic 36.5 %, and linoleic 20.2 %. Vinca rosea Linn syn. Lochnera rosea, Linn. (wt.%) lauric 0.2%, myristic 1.0%, palmitic 1.4 %, stearic 6.8 %, arachidic 1.3 %, behenic 0.6 %, oleic 73.6 %, and linoleic 15.1 %.     

Volatile by-products during heat polymerization of soybean oil

Volatile by-products during heat polymerization of soybean oil at 330°C were analyzed using GC-MS and NMR. Color and viscosity changes were monitored for the heat-polymerized soybean oil and the by-products. About 90% (w/w) of the by-products were decanoic, palmitic, linoleic, oleic, and stearic acids and cis-9-tricosene. The by-products also contained small amounts of 3-eicosene, 9,17-octadecadienal, and cyclotetracosene. The weight percentage of decanoic acid increased with reaction time, whereas those of other components showed no trends.     

Study of the seed oil ofSolanum platanifolium sims

Seed oils from species ofSolanum such asS. ferox (1),S. indicum (2),S. nudiflorum (3), andS. chacoense (4,5) have been shown to contain mainly linoleic, oleic, palmitic, and stearic acids. The seed oil fromS. platanifolium contains palmitic, stearic, oleic, linoleic, and hexadecenoic acids, and a mixture of C₂₀-C₃₁ alkanols and sterols.     

Fatty Acid Profiles of Some Fabaceae Seed Oils

The fatty acid profiles of six seed oils of the Fabaceae (Leguminosae) family are reported and discussed. These are the seed oils of Centrosema pubescens, Clitoria ternatea, Crotalaria mucronata, Macroptilium lathyroides, Pachyrhizus erosus, and Senna alata. The most common fatty acid in the fatty acid profiles of these oils is linoleic acid with palmitic, stearic, oleic and linolenic acids usually completing the most prominent fatty acids in these species. Long‐chain saturated fatty acids were observed in all oils. Centrosema pubescens and Macroptilium lathyroides exhibited the greatest amounts of long‐chain saturated fatty acids exceeding the amount of stearic acid in these oils. C. pubescens exhibited slightly more that 6 % C24:0 together with some fatty acids >C25 and M. lathyroides approximately 4 % C22:0 and 3 % C24:0. The results are comparatively discussed to previous data on the fatty acid profiles of Fabaceae species.     

Isolation and Evaluation of Stearin and Olein Fractions from Rice Bran Oil Fatty Acid Distillate by Detergent Fractionation and Conversion into Neutral Glycerides by Autocatalytic Esterification Reaction

Detergent fractionation (Lanza process) offers a valuable separation process for edible oils that contain varying amounts of saturated and unsaturated fatty acids. The rice bran oil fatty acid distillate (RBOFAD), obtained as a major byproduct of rice bran oil deacidification refining process, was fractionated by detergent solution into a fatty acid mixture as follows: low-melting (19.00 °C) fraction of fatty acids as olein fraction (44.50 g/100 g) and high-melting (49.00 °C) fatty acids as stearin fraction (37.15 g/100 g). A high amount of palmitic acid (42.75 wt%) is present in stearin fraction, while oleic acid is higher (48.21 wt%) in the olein fraction. The stearin and olein fractions of RBOFAD with very high content of free fatty acids are converted into neutral glycerides by autocatalytic esterification reaction with a theoretical amount of glycerol at high temperatures (130–230 °C) and at a reduced pressure (30 mmHg). Acid value, peroxide value, saponification value, and unsaponifiable matters are important analytical parameters to identity for quality assurance. These neutral glyceride-rich stearin and olein fractions, along with unsaponifiable matters, can be used as nutritionally and functionally superior quality food ingredients in margarine and in baked goods as shortenings.     

Fatty acid composition of Iranian citrus seed oils

Fatty acid compositions of seed oils from eight Iranian citrus fruits were determined. The ranges of values for major fatty acids were 21.8–29.4% palmitic, 3.1–7.60% stearic, 0.3–1.3% palmitoleic, 23.5–32.3% oleic, 33.5–39.8% linoleic, and 3.1–7.6% linolenic. Low amounts (up to 0.1%) of myristic and arachidic acids and traces of a few unidentified ones constituted minor fatty acids.     

Oxidative stability of natural and randomized high-palmitic-and high-stearic-acid oils from genetically modified soybean varieties

The oxidative stability of soybean oil triacylglycerols (TAG) obtained from genetically modified soybeans was determined before and after chemical randomization. Soybean oil oxidative studies were carried out under static oxygen headspace at 60°C in the dark and oxidative deterioration was monitored by peroxide value, monometric and oligomeric oxidation products, and volatile compounds. Randomization of the soybean oil TAG improved the oxidative stability compared to the natural soybean oil TAG. Oxidative stability was improved by three factors. Factor one was the genetic modification of the fatty acid composition in which polyunsaturated acids (such as linolenic and linoleic acids) were decreased and in which monounsaturated fatty acids (such as oleic) and saturated acids (palmitic and stearic) were increased. Factor two was the TAG compositional modification with a decrease in linolenic and linoleic-containing TAG and an increase in TAG with stearic and palmitic acids in combination with oleic acid. Factor three was the TAG structure modification accomplished by an increase in saturated fatty acids and a decrease in linoleic and linolenic acids at the glycerol moiety carbon 2. Presented at the AOCS Annual Meeting & Expo, Chicago, IL, May 10–13, 1998.     

Tissue culture of cocoa bean (Theobroma cacao L.): Incorporation of fatty acids into lipids of cultured cells

Suspension cell cultures of cocoa bean rapidly incorporated palmitic, stearic, oleic and linoleic acids into cellular lipids. Thus, 75 and 20% of [1-¹⁴C] palmitic acid was incorporated into polar lipids and triglycerides, respectively, after 48 hr. When [1-¹⁴C] oleic and [1-¹⁴C] linoleic acid were added separately, polar lipids consistently contained most of the radioactive fatty acids. Ca. 60% of the stearic acid accumulated as unesterified fatty acid in the cells. Palmitic and stearic acid were not desaturated, but oleic acid and linoleic acid were further desaturated. The kinetics of conversion of oleic acid and linoleic acid suggested a sequential desaturation pathway of 18∶1→18∶2→18∶3 in cocoa bean cell suspensions.     

Glucose fermentation in the presence of linoleic,oleic and stearic acids by a mixed culture

Long Chain Fatty Acid (LCFA) mixtures containing linoleic, oleic and stearic acids plus carbohydrates are found in a variety of effluents arising from fried food manufacture and milk processing. Accumulation of Volatile Fatty acids (VFAs) due to the presence of LCFAs may impair the operation of an anaerobic system treating effluents containing a mixture of triglycerides and carbohydrates. In this study, the effects of linoleic (C18:2), oleic (C18:1), and stearic (C18:0) acids on glucose fermentation were investigated at 21 °C using a culture acclimated to glucose. In cultures receiving ≥300 mg dm^?3 LCFAs, residual amounts of glucose remained after approximately 8 h and none was detected after 24 h. Acetate degradation was inhibited in the presence of 300 or more mg dm^?3 linoleic acid (LA), oleic acid (OA), or stearic acid (SA) with more acetate accumulation observed in cultures receiving LA. In comparison to the controls, similar amounts of propionate accumulation were observed in cultures receiving ≤100 mg dm^?3 of each LCFA. However, in cultures receiving ≥300 mg dm^?3 LCFAs, more propionate accumulated with complete removal observed within 20 days for only those cultures receiving oleic or stearic acids. Butyrate accumulation was observed only in cultures receiving ≥300 mg dm^?3 LA and none was detected after 10 days of incubation. Copyright © 2004 Society of Chemical Industry     

Determination of the fatty acid profile by 1H‐NMR spectroscopy

The common unsaturated fatty acids present in many vegetable oils (oleic, linoleic and linolenic acids) can be quantitated by ¹H‐nuclear magnetic resonance spectroscopy (¹H‐NMR). A key feature is that the signals of the terminal methyl group of linolenic acid are shifted downfield from the corresponding signals in the other fatty acids, permitting their separate integration and quantitation of linolenic acid. Then, using the integration values of the signals of the allylic and bis‐allylic protons, oleic and linoleic acids can be quantitated. The procedure was verified for mixtures of triacylglycerols (vegetable oils) and methyl esters of oleic, linoleic and linolenic acids as well as palmitic and stearic acids. Generally, the NMR (400 MHz) results were in good agreement with gas chromatographic (GC) analyses. As the present ¹H‐NMR‐based procedure can be applied to neat vegetable oils, the preparation of derivatives for GC would be unnecessary. The present method is extended to quantitating saturated (palmitic and stearic) acids, although in this case the results deviate more strongly from actual values and GC analyses. Alternatives to the iodine value (allylic position equivalents and bis‐allylic position equivalents) can be derived directly from the integration values of the allylic and bis‐allylic protons.     

Cis-5-monoenoic fatty acids ofCarlina (Compositae) seed oils

Seed oils ofCarlina corymbosa L. andC. acaulis L. containcis-5-octadecenoic acid as a major fatty acid (21–24%). This acid has not been previously reported as a constituent of Compositate seed oils. The predominant fatty acid in theCarlina oils is linoleic (50–52%); lesser amounts (≦10% each) of palmitic, stearic and oleic acids are also present. The oil ofC. acaulis has almost 2% ofcis-5-hexadecenoic acid;C. corymbosa oil includes minor amounts of some oxygenated fatty acids. Presented at the AOCS Meeting, New York, October 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.