Modification of vegetable oils

Summary 1. An investigation has been made of low-temperature crystallization from organic solvents as a means of effecting practical separations of the solid and liquid acids of unhydrogenated and hydrogenated cottonseed oils. 2. At any fixed temperature the most efficient separations were obtained in the highly polar solvents, acetone and methyl acetate. However, it was possible in any case to make nonpolar petroleum naphtha (Skellysolve B) fully equivalent to the polar solvents simply by conducting the crystallization at a temperature approximately 10° F. lower than that employed with the polar solvents. Ethyl acetate and methyl ethyl ketone were intermediate between petroleum naphtha and acetone or methyl acetate in their effectiveness. 3. By employing a solvent-fatty acid ratio of 4 to 1 by weight and conducting crystallizations at 5° F. or lower from acetone and −5° F. or lower from petroleum naphtha, the liquid fatty acids from unhydrogenated cottonseed oil could be reduced to below −2° C. in titer and to below about 3 per cent in saturated acid content. Under these conditions there was no appreciable crystallization of oleic acid. 4. At a solvent-fatty acid ratio of 6 to 1 and the same temperatures (5° F. for acetone and − 5° F. for petroleum naphtha) equally good separations could be made of the saturated fatty acids present in the mixed acids from hydrogenated cottonseed oil (I.V.=70). Separation of “iso-oleic” acids from the fatty acids of the hydrogenated oil took place over a wide range of temperatures, beginning at 35° F. in acetone and at 25° F. in petroleum naptha, and being incomplete (according to Twitchell analyses of the liquid acids) in either solvent at −15° F. However, the bulk of the higher melting iso-oleic acids was precipitated as the temperature approached −5° F. in acetone and −15° F. in petroleum naphtha. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Optimizing Reaction Conditions for the Isomerization of Fatty Acids and Fatty Acid Methyl Esters to Their Branch Chain Products

In order to improve the oxidative stability and cold flow properties of oleic acid or methyl oleate, branch chain isomerization was conducted using a beta zeolite catalyst. Reaction conditions of temperature (200–300 °C), pressure (0.1–3.0 MPa), and co-catalyst (0–2 wt%) were optimized based on branch chain conversion and the cloud point of the ester following the isomerization reaction of oleic acid or methyl oleate. Fourier transform infrared spectroscopy (FTIR) and Gas Chromatograph equipped with Mass Spectrometry (GC/MS) analyses were used to analyze and quantify the isomerization product samples, while the cloud point of each sample was tested. The lowest and therefore, best cloud point measured was −15.2 °C at conditions of 200 °C, 3 MPa, and 2% co-catalyst using methyl oleate as a starting material. The highest branch chain conversion achieved was 50% under conditions of 300 °C, 1.5 MPa and 0% co-catalyst using oleic acid as a starting material. The use of oleic acid and methyl oleate is based on whether it is optimal to carry out the skeletal isomerization before or after the esterification reaction. Performing the isomerization reaction on the ester was preferred over the fatty acid based on the trans isomerization and cloud point results. Reducing the unbranched trans isomers was desirable in obtaining a low cloud point.     

Liquid C-18 saturated acids derived from linseed oil

Liquid C-18 saturated monocarboxylic acids that fail to crystallize at −70°C. have been prepared from linseed oil, linolenic acid, and tung oil. Heating one part of linseed oil in three parts of glycol (weight-volume ratio) at 295°C. for 1 hr. with 25% excess sodium hydroxide, followed by distillation and hydrogenation of the resulting free fatty acid monomers and separation of the straight-chain components by low temperature crystallization from acetone, yielded these liquid acids. The relative proportions of cyclic acids, straight-chain monomeric acids, and polymer varied with the type of starting material and with the conditions employed. Cyclic acids in excess of 30% yields were obtained from linseed oil. Some hydroxylation of the fatty acids apparently takes place during cyclization; the amount increases with ascending temperatures, as evidenced by a rise in polyester content of the polymer fraction. Evidence indicates that the bulk of the unhydrogenated cyclic acids are vicinal disubstituted cyclohexadienes. Gas chromatography of the cyclic acids hydrogenated to an iodine value <1 shows that there are several components. These have not as yet been separated and positively identified. Presented at fall meeting, American Oil Chemists' Society, New York, N.Y., October 17–19, 1960. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Pure oleic acid from olive oil

Summary Oleic acid of 99–100% purity has been prepared in 36–43% yield from olive oil. The combination of two urea-adduct separations (at room temperature) and three acid soap crystallizations (at 3°C.) gives an oleic acid of high quality without recourse to fractional distillation or low-temperature solvent crystallization.     

Synthesis and Physical Properties of Tallow-Oleic Estolide 2-Ethylhexyl Esters

Tallow-oleic estolide 2-ethylhexyl (2-EH) esters were synthesized in a perchloric acid catalyzed one-pot process from industrial 90% oleic and tallow fatty acids at various ratios, while varying the ratio of tallow and oleic fatty acids, with the esterification process incorporated into an in situ second step to provide a functional fluid. Their viscosities ranged 57–80 cSt at 40 °C and 10.8–14.0 cSt at 100 °C with viscosity index (VI) 169–185. The 100% tallow estolide 2-EH ester had modest low-temperature properties (pour point = −15 °C and cloud point = −14 °C), while the 50:50 mixture of oleic and tallow fatty acids produced an estolide that had better low-temperature properties (pour point = −21 °C and cloud point = −21 °C) without a large negative effect on the oxidative stability. The oxidative stability increased as the amount of saturation increased (rotating pressurized vessel oxidation test (RPVOT) × 165–274 min). The tallow-oleic estolide 2-EH esters have shown remarkably low evaporative losses of only 1% loss compared to a 15–17% loss for commercial materials of similar viscosity grade. Along with expected good biodegradability, these tallow-oleic estolide 2-EH esters had acceptable properties that should provide a specialty niche. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Crystallization at low temperatures as a technique in the analysis of oils

Summary 1. A rapid method for determining the saturated, oleic, linoleic and linolenic acids in a 1-gram sample of fat has been described. 2. Saturated fatty acids were separated by quantitative crystallization from acetone solution at −40° C. 3. The three unsaturated acids, oleic, linoleic and linolenic, were calculated from the iodine and thiocyanogen values of the remaining liquid acids. 4. Analysis of known mixtures of fatty acids demonstrated the accuracy of the method to be approximately ±2 units percent. 5. Duplicate determinations of the fatty acid distribution in natural oils agreed within 0 to 4 units percent. 6. Data on the oleic, linoleic, and linolenic acid content of 15 seed oils were presented. Published with the approval of the Director of the Wisconsin Agricultural Experiment Station, Madison, Wisconsin. This work was supported in part by funds furnished by the Lever Brothers Company, Cambridge, Massachusetts, and the Wisconsin Alumni Research Foundation.     

The melting points of binary mixtures of oleic,linoleic, and linolenic acids

Summary 1. The melting points of binary mixtures of oleic, linoleic, and linolenic acids have been reported. 2. The oleic-linoleic acid system has eutectics for the α and β forms of oleic acid of 75.2 and 76.3 mole per cent linoleic acid, at −10.0° and −9.8°, respectively. 3. Linoleic and linolenic acid mixtures show only melting points intermediate between the pure acids. 4. The oleic-linolenic acid system has eutectics for the α and β forms of oleic acid of 82.7 and 85.5 mole per cent linolenic acid, at −15.7° and −15.1°, respectively. A cooperative organization participated in by the Bureaus of Agricultural Chemistry and Engineering and Plant Industry of the U. S. Department of Agriculture, and the Agricultural Experiment Stations of the North Central States of Illinois. Indiana, Iowa, Kansas. Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.     

Reactions of fatty materials with oxygen. XV. Formation of 9,10-dihydroxystearic acid and cleavage products in the oxidation of oleic acid and methyl oleate in acetic acid

Summary The autoxidation of oleic acid and methyl oleate in acetic acid solution at 25–30°, 65°, and 115–120° with a cobalt salt as catalyst has been studied. Samples were withdrawn at intervals and the oxidation products were analyzed and then separated into high-melting 9,10-dihydroxystearic acid, cleavage products, unoxidized and hydroxy materials, and polymers. The best yields of desired oxidation products were obtained at 65°. Yields of pure 9,10-dihydroxystearic acid, m.p. ≧128°, were 12–17% and cleavage products 64–68%, thus accounting for about 80% of the starting material. At 25–30° and 115–120°, yields of the above-mentioned products were low. A mechanism is proposed which accounts for the formation oftrans-9,10-epoxystearic acid from both oleic and elaidic acid autoxidized in the absence of solvent, and the consequent isolation of high-melting 9,10-dihydroxystearic acid when acetic acid is the solvent. Paper XIV is reference 10. Presented at the Fall Meeting of the American Oil Chemists’ Society, Chicago, Ill., Nov. 2–4, 1953. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Service, U. S. Department of Agriculture.     

Fractionation of menhaden oil and partially hydrogenated menhaden oil: Characterization of triacylglycerol fractions

Menhaden oil (MO) and partially hydrogenated menhaden oil (PHMO) were dry-fractionated and solvent-fractionated from acetone. After conversion to fatty acid methyl esters, the compositional distribution of saturated, monounsaturated, trans, and n−3 polyunsaturated fatty acids (PUFA) in the isolated fractions was determined by gas chromatography. Acetone fractionation of MO at −38°C significantly increased the n−3 PUFA content in the liquid fractions over that of starting MO (P<0.05). For PHMO, liquid fractions obtained by low-temperature crystallization (−38, −18, and 0°C) from acetone showed significant increases (P<0.05) in monounsaturated fatty acid (MUFA) content over that of the starting PHMO. For selected MUFA-enriched fractions, reversed-phase high-performance liquid chromatography (HPLC) was used to separate, isolate, and characterize the major triacylglycerol (TAG) molecular species present. Thermal crystallization patterns for these fractions also were determined by differential scanning calorimetry (DSC). The results demonstrated that under the appropriate conditions it is possible to dry-fractionate or solvent-fractionate MO and PHMO into various solid and liquid fractions that are enriched in either saturated, monounsaturated, polyunsaturated, or the n−3 classes of fatty acids. Moreover, characterization of these TAG fractions by reversed-phase HPLC gives insight into the compositional nature of the TAG that are concentrated into the various fractions produced by these fractionation processes. Finally, the DSC crystallization patterns for the fractions in conjunction with their fatty acid compositional data allow for the optimization of the fractionation schemes developed in this study. This information allows for the production of specific TAG fractions from MO and PHMO that are potentially useful as functional lipid products.     

Cyclic fatty acids: Separation from straight-chain fatty acids by urea adducting

A mixture containing 37% cyclic and 63% straight-chain fatty acids, made by high-temperature treatment of linseed oil fatty acids with alkali, was separated by the urea adduct method to give unsaturated cyclic fatty acids (nonadduct) in 95% purity and 90–95% yeild. Previous reports from this Laboratory describe a process for separating cyclic fatty acids from stearic acid by hydrogenation followed by crystallization at −40C. The urea adduct method avoids hydrogenation and low-temperature crystallization, and furthermore, unsaturated cyclic and unsaturated straight-chain products can be recovered as individual fractions. Then, by readducting the unsaturated straight-chain fatty acid fraction, the small amounts of palmitic and stearic acids are removed leaving an unsaturated fraction containing oleic, nonconjugated and conjugated linoleic and some unsaturated cyclic fatty acids. Presented at AOCS Meeting, Los Angeles, April 1966. No. Utiliz. Res. Dev. Div., ARS, USDA.     

The n−3 polyunsaturated fatty acid levels in rat tissue lipids increase in response to dietary olive oil relative to sunflower oil

In the present study, changes in phospholipid compositions of liver microsomes, erythrocyte membranes, platelets, aorta, cardiac muscle and brain of rats fed olive oil were compared with those of rats fed sunflower oil. Four groups of rats starting at weaning were fed for four weeks a basal diet containing 5 or 25% olive oil or sunflower oil. We found that oleic acid was higher and linoleic acid was lower in membrane phospholipids of olive oil fed rats compared to sunflower oil fed rats. Polyunsaturated fatty acids of the n−3 series were markedly elevated in all tissues of rats on the olive oil diets relative to those on the sunflower oil diets. The results are consistent with a lower linoleic/linolenic acid ratio induced by the olive oil diets, suggesting a positive correlation between olive oil ingestion and n−3 polyunsaturated fatty acid levels in cell and tissue lipids. The study suggests that an adequate intake of olive oil may enhance the conversion of n−3 fatty acids.     

Effect of free carboxylic groups on the course of sulfur trioxide sulfonation of unsaturated fatty acids

Summary The direct action of one mole of sulfur trioxide in liquid sulfur dioxide at atmospheric pressure at −10 to −9°C. on one mole of unsaturated fatty acids such as oleic acid, undecylenic acid, and crotonic acid yielded 85–90% of sulfonated products in which a monosulfonated derivative, rich in residual carbon to carbon unsaturation, predominates. Hydroxy sulfonates and sulfonated-sulfated products, postulated to form from carbyl sulfate intermediates, are present in lesser amounts. Esters of unsaturated fatty acids, such as n-propyl oleate, require at least two moles of sulfur trioxide for 80–90% yields of sulfonated product. These sulfonated products are postulated to form almost exclusively through the carbyl sulfate intermediate. The free carboxyl group apparently determines the course of sulfonation. Its action is believed to be that of first forming an acyl sulfate or mixed anhydride with sulfur trioxide, followed by hydrogen replacement in a methylene group, probably in an allyl position to the double bond, with a sulfonic acid group. The mechanism and nature of products resemble those previously observed by Suter in the dioxane-sulfur trioxide sulfonation of methallyl chloride (6). The sulfonated unsaturated reaction products from oleic and undecylenic acids exhibit lower double bond reactivity toward hydrogen and halogen addition than the unsulfonated starting materials. The monosulfonated oleic acid, because of its stability toward hydrolysis, holds promise as an important surface-active agent, particularly under acidic conditions. Patent covering the reaction products and their preparation has been applied for.     

Oxidative Evolution of Virgin and Flavored Olive Oils Under Thermo-oxidation Processes

Changes in the oxidative status of Chétoui olive oil were monitored to attest the efficiency of some bioactive compounds from aromatic plants to improve the stability of olive oils after a maceration process at different concentrations. Aromatized olive oils were prepared by addition of lemon and thyme extracts at four different concentrations (20–80 g kg⁻¹ of oils) to virgin olive oils. The following parameters were monitored: free fatty acids, peroxide value, ultra violet absorption characteristics at 232 and 270 nm, fatty acid composition and aromatic profiles. After thermo-oxidation processes, the oleic/linoleic acid ratio remained stable (4.5). Oxidative stability slightly decreased during thermo-oxidation processes. The heating of the oils changed their volatile profile and led to the formation of new volatile compounds, such as the two isomers of 2,4-heptadienal after heating at 100 °C or (E,Z)-2,4-decadienal and (E,E)-2,4-decadienal after thermo-oxidation at 200 °C. The use of lemon and thyme extracts modified the aromatic and the nutritional value of the olive oil by the transfer of some bioactive compounds, such as limonene and carvacrol. In contrast, the oxidative stability of the product did not change. Furthermore, the aromatized oils may be employed in seasoning and cooking of some foods.     

The effect of positional and geometrical isomerism on the dilatometric properties of some octadecenoic acids

Summary Four isomeric octadecenoic acids, oleic, elaidic, petroselinic, and petroselaidic, were prepared and their expansibility determined. The melting dilation of each acid was calculated and found to increase in the order oleic, petroselinic, petroselaidic, and elaidic. In each instance the melting dilation of the trans acid was greater than that of its cis isomer. Of the two cis acids studied, the melting dilation was less for the acid with the double bond farther from the carboxyl end of the carbon chain. The trans acids did not follow this pattern. At temperatures above 52°C., at which all acids were liquid, the absolute specific volumes of the acids were very nearly equal whereas at temperatures below −7°C, at which all were in the solid state, the specific volumes of petroselinic and elaidic acids were at variance with the specific volumes of oleic and petroselaidic acids. This variance must be attributed to differences in crystal packing. Oleic acid clearly showed the two polymorphic forms previously recognized and, in addition, apparently reversibly transformed at about −5°C., indicating the possible existence of a third polymorphic form. These transformations of oleic acid occurred regardless of tempering, and without visual melting. The other three acids did not exhibit polymorphism under the conditions employed in the dilatometric measurements. Presented at the 44th Annual Meeting of the American Oil Chemists' Society New Orleans, La., May 4–6, 1953. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Increase in the γ-linolenic acid content by solvent winterization of fungal oil extracted fromMortierella genus

The fungal oil extracted fromMortierella ramanniana var.angulispora (IFO 8187) was solvent winterized in order to raise the content of γ-linolenic acid (GLA). Effects of winterization conditions (solvent, oil concentration in the solvent and temperature) and changes of glyceride compositions were discussed. The fungal oil was separated into four diglycerides and 17 triglycerides (TG) with high performance liquid chromatography. The predominant species were POO, POP and LOP, whose contents were 24.4, 22.9 and 9.4% of the total TG, respectively. Ethanol at 4°C gave the highest GLA content of 10.5% in spite of lower yield than with acetone at −20°C. The highest separation efficiency for GLA (η_GLA) was 0.27 with acetone at −20°C and 10% oil concentration, resulting in 8.3% of GLA from the fungal oil at 5.7% LGA. In case of lower oil concentration at 5–20%, η_GLA showed higher in the following order: acetone (−20°C)>n-hexane (−20°C)>acetone (4°C)>petroleum ether (−20°C). The winterization process also proved to be effective for the separation of TG type, Sa₂U (Sa; saturated fatty acid; U, unsaturated fatty acid) into the crystallized fraction and SaU₂ into the liquid fraction. Acetone at −20°C showed higher separation efficiency for triunsaturated TG than the other solvents.     

Synthesis of δ-stearolactone from oleic acid

δ-Stearolactone was prepared from oleic acid using concentrated sulfuric acid under various conditions in the presence of polar, nonparticipating solvents. δ-Stearolactone was formed in as high as 15∶1 ratios over the thermodynamic product, ψ-lactone, in the presence of methylene chloride, 100% wt/vol, at room temperature with two equivalents of sulfuric acid for 24 h. This procedure is applicable to other olefinic fatty acids such as estolides and fatty acid methyl esters. Temperature plays a role in the regioselectivity of the cyclization for δ-lactone, as lower temperatures (20°C) gave higher σ/ψ ratios. At higher temperatures (50°C) in the presence of sulfuric acid and methylene chloride the yield of lactone was 75% but with a σ/ψ ratio of only 0.3∶1. Cyclization of oleic acid to lactone also occurred with other acids. Oleic acid underwent reaction with perchloric acid, one equivalent, in the absence of solvent at 50°C, which yielded σ-lactone in a modest yield with a 3.1 σ/ψ ratio. The same temperature effect was observed with perchloric acid that was observed in the case of sulfiric acid. Because σ-stearolactone is much more reactive than the corresponding fatty acid, fatty acid ester, or ψ-lactone, we believe that it will be a useful synthon for many new industrial products including new biodegradable detergents.     

Liquid to Semisolid Rheological Transitions of Normal and High-oleic Peanut Oils upon Cooling to Refrigeration Temperatures

Rheological transitions of peanut oils cooled from 20 to 3 °C at 0.5 °C/min were monitored via small strain oscillatory measurements at 0.1 Hz and 1 Pa. Oils were from nine different cultivars of peanut, and three oils were classified as high-oleic (approximately 80% oleic acid). High-oleic oils maintained an overall liquid-like character at 3 °C for 2 h. In contrast, several normal (non high-oleic) peanut oils displayed a predominantly elastic (solid-like) response after 2 h at 3 °C. Increases in viscoelasticity were associated with lipid crystallization events as confirmed by DSC. The higher (p < 0.001) liquid viscosities and increased (p < 0.001) contents of oleic acid, which has a more non-linear structure as compared to other fatty acids typical in these oils, were hypothesized to hinder crystallization in high-oleic oils. Changes in viscoelasticity at 3 °C were greatest for three normal oils that had the significantly (p < 0.001) highest content of C20:0 and/or C22:0 fatty acids, and these long, saturated hydrocarbon chains are hypothesized to promote crystallization. No peanut oil maintained clarity after 5.5 h at 0 °C (modified cold test used to screen salad oils); however, these data as a whole suggest strategies for breeding and/or processing peanut oils for enhanced resistance to crystallization. The use of trade names in this publication does not imply endorsement by the United States Department of Agriculture: Agricultural Research Service.     

Modification of vegetable oils. XIV. Properties of aceto-oleins

Summary Pure 1,2-diaceto-3-olein was prepared by acetylating mono-olein. A mixture of aceto-oleins was prepared by acetylating a mixture of mono-, di-, and trioleins derived from commercial oleic acid. Several natural oils were acetylated either by ester-ester interchange with triacetin or by glycerolysis followed by acetylation. The various products were examined for cloud and solid points, point of complete melting, and consistency. The 1,2-diaceto-3-olein, which contains 19.5% of acetyl group on a weight basis, has a melting point of −18.3°C. while the mixture of aceto-oleins, which contained 14.3% of acetyl on a weight basis, melted at −24°C. Acetylation of the natural oils raises in most instances their cloud and solid points and point of complete melting, but it also greatly increases their plasticity at lower temperatures. Aceto-compounds were used to plasticize highly hydrogenated cottonseed oil. These mixtures were prepared so that they possessed the consistency of margarine oil at room temperature. These mixtures, when compared with partially hydrogenated oil, butterfat, or a mixture of cottonseed oil and hydrogenated cottonseed oil, were softer below room temperature and firmer above room temperature. A margarine-like product containing 79% of aceto-olein and 18.5% of highly hydrogenated cottonseed oil had a practically constant consistency over the temperature range of −15° to 49°C. (5° to 120°F.). Presented at the 26th Fall Meeting of the American Oil Chemists' Society, Cincinnati, O., Oct. 20–22, 1952. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Lipase-catalyzed acidolysis of tristearin with oleic or caprylic acids to produce structured lipids

Two different structured lipids (SL) were synthesized by transesterifying tristearin with caprylic acid (C8∶0) or oleic acid (C18∶1). The objective was to synthesize SL containing stearic acid (C18∶0) at the sn-2 position as possible nutritional and low-calorie fats. The reaction was catalyzed by IM60 lipase from Rhizomucor miehei in the presence of n-hexane. The effects of reaction parameters affecting the incorporation of caprylic acid into tristearin were compared with those for incorporating oleic acid into tristearin. For all parameters studied, oleic acid incorporation was higher than caprylic acid. The range of conditions favorable for synthesizing high yields of C8∶0-containing SL was narrower than for oleic acid. An incubation time of 12–24 h and an enzyme content of 5% (w/w total substrates) favored C8∶0 incorporation. The mole percentage of incorporated C18∶1 did not increase further at enzyme additions greater than 10%. C18∶1 incorporation decreased with the addition of more than 10% water (w/w total substrates) to the tristearin-oleic acid reaction mixture. Increasing the mole ratio of fatty acid (FA) to triacylglycerol increased oleic acid incorporation. The highest C8∶0 incorporation was obtained at a 1∶6 mole ratio of tristearin to FA. Positional analysis confirmed that C18∶0 remained at the sn-2 position of the synthesized SL. The melting profiles of tristearin-caprylic acid and tristearin-oleic acid SL displayed peaks between −20 to 30°C and −20 to 40°C, respectively. Their solid fat contents (∼25%) at 25°C suggest possible use in spreads or for inclusion with other fats in specialized blends.     

Triglyceride composition of olive oil,cottonseed oil and their mixtures by low temperature crystallization and gas liquid chromatography

Crystallization and gas liquid chromatography (GLC) have been used to characterize the triglyceride composition of olive and cottonseed oil and their precipitates from acetone or methanol/acetone (10:90, v/v) at −2 C. The precipitate obtained after a 24 hr crystallization of a 5% (w/v) solution of the sample in acetone or methanol/acetone (10:90, v/v) at −2 C was named Precipitate I (P-I); that isolated after 2 successive crystallizations under identical conditions was named Precipitate II (P-II). In each case, the ratio of oleic to linoleic acid (O/L) was calculated and proved to be a useful index for detecting adulteration of olive oil with cottonseed oil. In olive oil, the ratio O/L increased from the original sample to its precipitates, whereas in cottonseed oil and the adulterated samples the ratio O/L was lower in the precipitates than in the original sample. For olive oil P-II, the lowest value of the ratio O/L was 8.4; for the adulterated samples it was 7.6. On the basis of this index, adulteration of olive with cottonseed oil as low as 10% can be detected. Hydrolysis of P-1 by porcine pancreatic lipase and analysis of the fatty acids of the sn-2 position showed that the enrichment factor of linoleic acid varied between 1.11–1.30 for olive oil and between 1.55–1.90 for the adulterated samples. Even for adulteration with 5% cottonseed oil, the enrichment factor appears to increase (1.55–1.57) and can be used as a criterion for adulteration.