Linoleic acid solvents

When tallow fatty acids are the feed, stearic acid (actually 60/40 C16/C18) and oleic acids are the products. Solvent separation is also used to separate stearic acid from isostearic acid when hydrogenated monomer is the feed, and oleic acid from linoleic acid when using tall oil fatty acids as feed. 

Liquid—hquid extraction can be used to obtain high purity linoleic acid from safflower fatty acids or linoleic acid from linseed fatty acids using furfural and hexane as solvents (18). High purity linoleic acid has been obtained from sunflower fatty acids using a dimethylformamide and hexane solvent system (19). 

The clay-cataly2ed iatermolecular condensation of oleic and/or linoleic acid mixtures on a commercial scale produces approximately a 60 40 mixture of dimer acids and higher polycarboxyUc acids) and monomer acids (C g isomerized fatty acids). The polycarboxyUc acid and monomer fractions are usually separated by wiped-film evaporation. The monomer fraction, after hydrogenation, can be fed to a solvent separative process that produces commercial isostearic acid, a complex mixture of saturated fatty acids that is Hquid at 10°C. Dimer acids can be further separated, also by wiped-film evaporation, iato distilled dimer acids and trimer acids. A review of dimerization gives a comprehensive discussion of the subject (10). 

RP-HPLC with nonaqueous solvents and UVD at 246 nm was developed for the determination of low level POVs of vegetable oils. These measurements are specific for conjugated diene peroxides derived from vegetable oils with relatively high linoleic acid content. These measurements may be supplemented by nonspecific UVD at 210 nm and ELSD for detection of all eluted species. The elution sequence of the triglycerides in a nonaqueous RP-HPLC is linearly dependent on the partition number of each species, Vp, which is defined as = Nq — 2Ni, where Nq is the carbon number and is the double bond number. In the case of hydroperoxides = Nq — 2Nd — Vhpo, where Vhpo is the number of hydroperoxyl groups in the molecule (usually 1 for incipient POV). For... 

BASIC PROTOCOL I PREPARATION OF FATTY ACID METHYL ESTERS FROM LIPID SAMPLES CATALYZED WITH BORON TRIFLUORIDE IN METHANOL In this method, lipid samples are first saponified with an excess of NaOH in methanol. Liberated fatty acids are then methylated in the presence of BF3 in methanol. The resulting fatty acid methyl esters (FAMEs) are extracted with an organic solvent (isooctane or hexane), and then sealed in GC sample vials for analysis. Because of the acidic condition and high temperature (100°C) used in the process, isomerization will occur to those fatty acids containing conjugated dienes, such as in dairy and ruminant meat products, that contain conjugated linoleic acids (CLA). If CLA isomers are of interest in the analysis, Basic Protocol 2 or the Alternate Protocol should be used instead. Based on experience, this method underestimates the amount of the naturally occurring cis-9, trans-11 CLA isomer by -10%. The formulas for the chemical reactions involved in this protocol are outlined in Equation D1.2.1 Saponification RCOO-R + NaOH, RCOO-Na + R -OH v 100°C DC Esterification RCOO-Na + CH,OH r 3 v RCOO-CH, + NaOH ioo°c ... 

An HPLC chromatograph was used together with a mass detector (when required, a stream splitter (app. 10 1) was inserted between the column and the detector). A column (250 X 4.6-mm ID) of NUCLEOSIL 5SA was flushed with 1% aqueous ammonium nitrate solution at a flow rate of 0.5 ml/min for 1 h, then with distilled water at 1 ml/min for 1 h. Silver nitrate (0.2 g) in water (1 ml) was injected onto the column in 50-/zl aliquots at 1-min intervals silver began to elute from the column after about 10 min. Twenty minutes after the last injection, the column was washed with methanol for 1 h, then with 1,2-dichloroethane-dichloromethane (1 1) for another hour. The three solvent reservoirs contained the following (A) 1,2-dichloroethane-dichloromethane (1 1) (B) acetone and (C) acetone-acetonitrile (9 1). For linoleic acid-rich seed oils, gradients of A were employed to 50% A-50% B over 15 min, then to 50% B-50% C over a further 25 min and held there for 5 min. For linolenic acid-rich seed oils, C was changed to acetone-acetonitrile (4 1), and the flow rate was increased to 1 ml/min gradients of A were utilized to 50% A-50% B over 10 min, then to 70% B-30% C over 20 more min, and finally to 100% C over another 30 min. 

The concentration of fats and related substances in molasses is low analytical values depend on the extracting solvent.126 These tenaciously retained materials can be removed by fractionation of blackstrap on fuller s earth clay.70 Chromatography on a calcium silicate of the fat fraction of Cuban molasses led to the isolation of melissyl alcohol, a phytosterol fraction, chlorophyll a and a fat fraction containing a glyceride of linoleic acid.70 Stigmasterol and syringic acid are reported as ether-extractable constituents of molasses.127... 

Conjugated linoleic acid (CLA) may have a role in improving the nutritional and health properties of milk fat (Wahle et al., 2004 see Chapter 3). A range of lipases was compared for their efficacy of catalysing the incorporation of CLA into milk fat in solvent-free systems (Garcia et al., 2000). It was concluded that it was technically feasible to incorporate CLA into milk fat with the use of immobilised Candida antarctica lipase. However, the nutritional benefits and physical properties of the CLA-enriched milk fat need to be investigated prior to consideration of this technology for industrial application. 

Linoleic Acid occurs as a colorless to pale yellow, oily liquid that is easily oxidized by air. It is an essential fatty acid and the major constituent of many vegetable oils, including cottonseed, soybean, peanut, corn, sunflower seed, safflower, poppy seed, and linseed. Its specific gravity is about 0.901, and its refractive index is about 1.469. It has a boiling point ranging from 225° to 230° and a melting point around -5°. One milliliter dissolves in 10 mL of petroleum ether. It is freely soluble in ether soluble in absolute alcohol and in chloroform and miscible with dimethylformamide, fat solvents, and oils. It is insoluble in water. 

Safflower Oil, Unhydrogenated, occurs as a light yellow oil. It is obtained from the plant Carthamus tinctorius (Fam. Asteraceae) by mechanical expression or solvent extraction. It is refined, bleached, and deodorized to substantially remove free fatty acids, phospholipids, color, odor and flavor components, and miscellaneous other non-oil materials. It is a liquid at 21° to 21°, but traces of wax may cause the oil to cloud unless removed by winterization. Safflower Oil has the highest linoleic acid [(Z),(Z)-9,12-octadecadienoic acid] content (typically about 78% of total fatty acids) of any known oil. It is free from visible foreign matter at 21° to 21°. 

Crystallization is used to separate saturated fats and oleic acid from linoleic acid. If a highly concentrated product is required, the linoleic acid may be crystallized once or repeatedly as the last step in purification. Crystallization is a mild procedure but usually requires the use of a solvent (108) such as acetone or methanol. The use of low boihng point and flammable solvents raises concerns over plant safety, government regulations on manufacturing, and market acceptance of the product. Furthermore, the removal of oleic acid by crystallization in solvent is only possible by lowering the temperature of the liquor to below —40°C (108). To crystallize linoleic acid, the temperature must be reduced to —75 °C. 

Dry or solvent free crystallization is also possible but these methods often require the addition of crystal modifiers that become incorporated into the product (108). Losses during crystallization can be very high as the crystals entrain large amounts of fatty acid. However, these losses may be reduced by physically pressing the crystals to remove the entrained solution (109). Linoleic acid-rich products of dry crystallization would be preferred starting materials for CLA production over those of solvent crystallized products but the losses incurred in dry crystallization may prohibit this method of manufacture. Crystal modifiers may be selected so that they do not adversely affect the quality or acceptance of the final product. 

Fatty acids may also be enriched by the use of various absorption media. Molecular sieves can separate saturated fatty acids from unsaturated fatty acids dissolved in acetone (110). Oleic acid and linoleic acid dissolved in blends of solvents, including acetonitrile, tetrahydrofuran, water, and formamide, may be separated using cross-linked polystyrene polymers such as Amberlite XAD-2 or XAD. ... 

Selective extraction methods using two-phase solvent systems may also be used to enrich fatty acids. Solvent systems such as dimethyl formamide, hexane, and ethylene glycol can form a two-phase system that effectively partitions sunflower oil TAGs rich in linoleic acid from those depleted in linoleic acid (111). TAGs partitioned in this way may contain up to 84.7% linoleic acid. This method would not likely be used in industry because the magnitude of the losses are usually unacceptable. 

The importance of complexing and the polarity of the environment has been emphasized. When metal phthalocyanines and metal stearates were compared in ethyl benzoate as solvent, their catalytic efficiencies in the autoxidation of O.IM linoleic acid were of a comparable order of magnitude when the metal phthalocyanines and the metal stearates were present at concentrations of 2 X and... 

Saponification refers to alkaline hydrolysis of fats and oils to give glycerol and the alkali metal salt of a long chain fatty acid (a soap). In this experiment saponification of olive oil is accomplished in a few minutes by use of a solvent permitting operation at 160°C. Of the five acids found in olive oil, listed in Table 1, three are unsaturated and two are saturated. Oleic acid and linoleic acid are considerably lower melting and more soluble in organic solvents than the saturated components, and when a solution of the... 

Alpha-tocopherol is a highly lipophilic compound, and is an excellent solvent for many poorly soluble drugs.Of widespread regulatory acceptability, tocopherols are of value in oil- or fat-based pharmaceutical products and are normally used in the concentration range 0.001-0.05% v/v. There is frequently an optimum concentration thus the autoxidation of linoleic acid and methyl linolenate is reduced at low concentrations of alpha tocopherol, and is accelerated by higher concentrations. Antioxidant effectiveness can be increased by the addition of oil-soluble synergists such as lecithin and ascorbyl palmitate. " ... 

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