Solvent-Assisted Crystallization of Fatty Acid Alkyl Esters from Animal Fat

An easy and efficient method for the separation of saturated and unsaturated fatty acid mono alkyl esters, prepared from animal fat, was developed. The most efficient separation was achieved by the use of solvents such as methanol and acetone at low temperatures. The dilution of the alkyl esters with 10 times the amount of solvent (10:1 v/w) and storage of the mixture for 4 h at ?22 °C could be defined as optimum conditions. After filtration of the saturated fraction at the corresponding temperature very pure fractions were obtained. For fatty acid methyl esters deriving from tallow, with an initial content of saturated fatty acids of almost 50 %, a saturated ester fraction with only 5 % unsaturated fatty acids and an unsaturated ester fraction with about 9 % of saturated fatty acids could be obtained. The solvent easily could be recovered by distillation. In addition fatty acid ethyl, 1‐propyl, 2‐propyl, 1‐butyl, tert‐butyl and 3‐methyl‐1‐butyl esters were prepared and separated into saturated and unsaturated fractions. All fractions were analyzed according to the fatty acid compositions and showed similar or slightly worse results compared to the methyl esters. The cold filter plugging points of the unsaturated fractions were measured, showing the lowest value for the unsaturated methyl ester fraction at ?26 °C. The fractionation with the use of solvents is an easy tool in order to obtain fatty acid alkyl esters with excellent cold temperature behavior out of animal fat.     

Chemical Properties and Fatty Acid Composition of Thunbergia fragrans Roxb. Seed Oil

The physicochemical and fatty acid compositions of seed oil extracted from Thunbergia fragrans were determined. The oil content, free fatty acids, peroxide value, saponification value and iodine value were 21.70 %, 2.25 % (as oleic acid), 9.6 (mequiv. O₂/kg), 191.71 (mg KOH/g) and 127.84 (g/100 g oil) respectively. The fatty acid profiles of the methyl esters showed the presence of 90.16 % unsaturated fatty acids and 9.84 % saturated fatty acids. Palmitoleic acid, which is usually found in marine foods and is unique in seed oils of botanical origin, was the major component (79.24 %). The oil can also be used in industries for the preparation of liquid soaps, shampoos and alkyd resin.     

Supercritical Carbon Dioxide Fractionation of Anhydrous Milk Fat

Supercritical carbon dioxide was used to fractionate anhydrous milk fat. Six fractions were produced at 40, 50 and 60 °C using pressure values of 10, 20, 25, 30, 33 and 36 MPa. The fractions were analyzed for fatty acids, thermal behavior, iodine and color values. Composition and yield of fatty acid methyl esters were evaluated at different fractionation conditions in relation to the original milk fat values. Short chain fatty acids (C₄–C₈), medium chain fatty acids (C₁₀–C₁₄) and total saturated fatty acids were decreased from fraction obtained in the order of 10–36 MPa, while long chain fatty acids (C₁₆–C_18:2) and total unsaturated fatty acids were increased. Fractions obtained in the raffinate stage of the fractionation exhibited higher melting behavior that obtained at the low CO₂ pressures. The higher iodine value of raffinate fraction indicated that fraction was richer in oleic acid. Fractions produced at low pressures had lower melting behavior than those obtained at high pressures. Yellowness Index and b* values increased in raffinate fraction due to concentration of carotenoids.     

Empirical relationships between iodine value and polyunsaturated fatty acid content in marine oils and lipids

From data obtained in this laboratory two empirical formulas have been developed which correlate polyunsaturated fatty acids indicated by GLC analyses with iodine values of marine oils or their fatty acid methyl esters. These formulas have been applied to data from the literature with good agreement. It is suggested that these formulas function only with fats having the basic composition of marine lipids, which consist principally of saturated, monounsaturated and very highly unsaturated fatty acids. The presence of modest amounts of dienoic and trienoic fatty acids such as are found in freshwater aquatic life and in land animals makes the formulas inapplicable, suggesting their use to distinguish marine fish oils and lipids from other types. The formulas could be particularly useful in technological applications of marine oils where a rapid and approximate knowledge of amount of polyunsaturated fatty acids is desirable.     

Direct determination of saturated fatty acids in fats,oils, and methyl esters

Summary A direct gravimetric method has been developed for the determination of saturated fatty acids in fats, oils, and methyl esters. The procedure involves methanolysis of the triglycerides to produce methyl esters, followed by oxidation of the unsaturated methyl esters by potassium permanganate. The undesired, acidic oxidation products are removed by alkaline washing and the saturated methyl esters thus isolated are weighed directly. The method is intended for the determination of saturated fatty acids having C₁₆ or longer carbon chains. Small quantities of C₁₄ saturated acids will be included in the determination if present with other higher saturated acids. The method is applicable to both natural and hydrogenated vegetable oils. It is not applicable to oils containing large amounts of C₁₄ and lower saturated acids. Concentrations of saturated acids ranging from 3 to 90% in known glyceride mixtures and from 0.3 to 95% in mixtures of methyl esters were determined with an average difference from the calculated value of 0.8%. Replicate determinations on samples in the 10 to 30% saturates range gave a standard deviation of 0.3 to 0.4%. Presented at the spring meeting, American Oil Chemists’ Society, New Orleans, La., April 28 to May 1, 1957     

The fungicidal activity of the unsaturated fatty acids and quaternary salts prepared from fish oils

Summary Saturated and unsaturated fatty acids and 10 unsaturated fatty acid fractions and ethyl esters of unsaturated fatty acid fractions prepared from fish oils were tested on their inhibitory activity againstCandida albicans. Oxidation of highly unsaturated fractions from fish oil and ethyl esters of unsaturated fatty acid fractions of menhaden, pilchard, and cod liver oils increases their antifungal activity. Saturated and unsaturated quaternaries were tested for their antifungal activity. Hexadecyltriethylammonium bromide and hexadecylpyridinium bromide showed the highest activity againstCandida albicans, Aspergillus niger, andRhyzopus nigricans. Any lengthening of the carbon chain more than C₁₆ weakened the activity of both saturated triethylammonium bromide and pyridinium bromide. An increase of unsaturation enhanced it. The antifungal activity of quaternaries prepared from fish oils was about 4,000 times stronger than that of oxidized highly unsaturated fatty acid fractions prepared from fish oils. The decisive factor in the highly inhibitory activity of quaternaries against fungi might depend on their positively charged portion since the surface of microorganisms is, as a rule, negatively charged. Aided by a grant from the Collett-Week Company, Ossining, N. Y.     

A quantitation problem in the open tubular gas chromatography of fatty acid esters from cod liver lipids

Methyl esters of fatty acids of marine origin contain large amounts of highly unsaturated long-chain fatty acids. It is shown that, although esters of saturated and monounsaturated fatty acids can be quantitatively analyzed on open tubular columns with a flame ionization detector there are serious losses of the long-chain highly unsaturated fatty acids of marine oils on the column. Through comparison of chain-length composition and iidine value some correction factors are suggested for the highly unsaturated fatty acids which permit reasonably accurate analyses.     

Application of methoxy-bromomercuri-adduct fractionation to the analysis of fatty acids of partially hydrogenated marine oils

The fatty acids of a refined and of a partially hydrogenated menhaden oil, iodine value (IV) 84.5, were separated into different classes (e.g., monoene, diene, including pentaene and hexaene) by thin layer chromatography (TLC) of their methoxy-bromomercuri-adducts (MBM). In the solvent system hexane: dioxane, the separation of fatty acids occurred according to the degree of unsaturation. No influence was exerted by either the geometry or the position of the ethylenic bonds. The effect of the various chain lengths (C₁₄−C₂₂) was to broaden the bands, but no overlap occurred among the chain lengths. A wide range of C₂₀ unsaturated fatty acids were prepared by the hydrazine reduction of 20∶5-Δ5,8,11,14,17. These were separated into groups as MBM adducts and identified by comparison of their experimental and calculated equivalent chain lengths (ECL) in gas liquid chromatography (GLC) on SILAR-5CP and SILAR-7CP columns. This confirmed that GLC did not totally separate all groups of isomers of different degrees of unsaturation. The quantitative analysis of both refined and partially hydrogenated (IV-84.5) menhaden oils by GLC was effected by the recovery of the fatty acid methyl esters from the MBM adduct TLC bands with the addition of methyl heptadecanoate (17∶0) as an internal standard, followed by analysis of the different fractions on open-tubular columns coated with SILAR-5CP. For methylene- and nonmethylene-interrupted unsaturated acids, 100% recovery from the MBM adducts was achieved, but in the case of the conjugated dienes the maximal recovery was 70%.     

Enzymatic epoxidation of soybean oil methyl esters in the presence of free fatty acids

Epoxides of soybean oil methyl esters (SMEs) are biodegradable, non‐toxic, and renewable epoxy plasticizers. The objective of the present work was to investigate the effects of free fatty acids on the enzymatic epoxidation of SMEs. The results showed that the epoxidation of SMEs depended on the type of the added free fatty acid. For saturated (≤C_18:0) and monounsaturated free fatty acids, the epoxy oxygen group content (EOC) of SMEs increased with increasing carbon chain length of free fatty acids; for branched‐chain unsaturated free fatty acids, the EOC of SMEs decreased in the presence of hydroxyl group (OH) and hydroperoxide (OOH) of free fatty acids; the EOC of SMEs decreased with increasing number of double bonds of free fatty acids. The maximum EOC and the initial epoxidization rate (V₀) linearly decreased with increasing peroxide value of SMEs. The highest EOC (6.87 ± 0.3%) of SMEs was obtained using behenic acid as reaction material, which was similar with that of stearic acid (EOC 6.75 ± 0.2%).     

Highly unsaturated fatty acids. II. Fractionation by urea inclusion compounds

Summary 1. Urea segregation has been found to be a useful tool in concentration of highly unsaturated acids and esters. Fatty acids and esters derived from fish oils and methyl esters of hog adrenal fatty acids have been fractionated, and the polyunsaturated acids have been enriched. 2. The tendency for fatty acids and esters to combine with urea decreases with increasing unsaturation. Combination is favored by lowered temperature. Polyunsaturated acids are concentrated in the final filtrate whereas esters of these acids appear in the final inclusion compound fractions. Fatty acid concentrates have been obtained with iodine values ranging from 294 to 356. Bound esters exhibited iodine values as high as 338. 3. The increased chain length brought about by esterification has a minor role in increasing the yield of inclusion compounds. Likewise, shifting of the terminal polar group in an acid toward the center of the molecule by esterification does not explain the higher yield of inclusion compound from esters. 4. The improved tendency of esterified acids to form urea inclusion compounds is probably due to blocking of association of acid groups. This effect is found in unsaturated acids and in short chain saturated acids. In long chain saturated acids and esters this effect is not noticed. Both give high yields of inclusion compounds because the effect of the carboxyl group is overshadowed by the high energy of formation contributed by the long carbon chain. Taken from a dissertation presented by A. M. Abu-Nasr to the Graduate School of Texas Agricultural and Mechanical College in partial fulfillment for the requirements of the Ph.D. degree, May, 1953. Supported in part by contract N8onr-66218 of the Office of Naval Research. Hormel Institute publication No. 93.     

Distribution of individual fatty acids in the crystallization fractions of lard

Distribution of the individual fatty acids in the triglycerides of lard was determined by fractional crystallization, partial enzymatic hydrolysis with steapsin, and fatty acid analyses by GLC. It was found that none of the individual fatty acids corresponded to a random distribution in the crystallization fractions, but that the distribution of the total saturated and total unsaturated acids was very nearly random. The short chain fatty acids, C₁₄ and C₁₆, both saturated and unsaturated, were found to be more predominant in the 2-position than in the 1- and 3-positions of the lard triglycerides. All of the C₁₈ fatty acids were found to be more predominant in the 1- and 3-positions.     

Fatty acid compositions of corn oils in relation to oil contents of the kernels

Summary The fatty acid compositions of 13 oils from corns having oil contents over the range of 1.6 to 11.5% oil, d.b., were determined either by a spectrophotometric technique applied to the whole oil or by the methyl ester fractional distillation technique. Linear relationships between iodine values and fatty acid compositions, between oil contents of the corns and iodine values, and between oil contents and fatty acid compositions were determined. An increase in oil content of the corn is accompanied by a decrease in iodine value and linoleic acid content of the oil and by an increase in oleic acid and saturated acids.     

A rapid method for concentrating highly unsaturated fatty acid methyl esters in marine lipids as an aid in their identification by GLC

The selective solubility of unsaturated fatty acid methyl esters in nitromethane at temperatures down to −20C can be used to concentrate highly unsaturated methyl esters. With a typical sample of marine oils methyl esters having an iodine value of 110–190, a concentrate can be ready for GLC analysis in an hour or less and the nitromethane layer can be injected directly for analysis in GLC apparatus with ionization detectors. Examples of the use of the method in the identification of component fatty acids in herring oil are given.     

Studies on characterization and variation in triglyceride fatty acids from punt/us sarana body lipids

Body lipids of P. sarana of four different sizes were fractionated into phospholipids, neutral lipids, nonsaponifiables, total fatty acids, polyunsaturated, monounsaturated and saturated fatty acid fractions. Percentage composition of each fraction was determined. The triglyceride fatty acids were identified by thin layer and gas liquid chromatography. C₈ to C₂₃ fatty acids including both odd numbered and branched chain acids were detected. The major constituents were C₁₄, C₁₅, C₁₆, C_16:1, C₁₈ C_18:1, C_18:2, C_18:3; forty-three other acids were detected in lower proportions. Composition of each fatty acids and their variation with size have been discussed.tP. sarana body lipids in general showed a behavior typical of fresh water fish by having a higher percentage of saturated C₁₆ and unsaturated C₁₈ acids and a lower percentage of unsaturated C₂₀ acid.     

Production of branched-chain fatty acids from sterculia oil

Methyl sterculate was rearranged by use of 0.5% of rhodium catalyst to isomeric conjugated diene fatty acid methyl esters containing both methylene-and methyl-branched isomers. The rearanged products were hydrogenated directly to saturated, methyl-substituted, branched-chain fatty acid methyl esters with the methyl substituent at one of the positions formerly occupied by the cyclopropenoid ring. The crude branched-chain fatty acids from these esters were purified by recrystallization from a mixed solvent of ethanol and water (80:20, v/v) and flash distillation; the product contained about 90% of branched-chain fatty acids (C₁₉:80%, C₁₈:10%). Esters of the branched-chain fatty acid were prepared with 2-ethylhexyl alcohol or trimethylolpropane, and the characteristic properties of these esters were investigated. The branched-chain fatty esters appear to have potential utility in lubricants; other uses may be possible. Presented at the AOCS meeting in New Orleans, May 1981.     

Synthesis and Surface Active Properties of Sulfonated Acrylate Esters Based on Al‐Cedre Oil

Sulfonated acrylate esters have been synthesized by using renewable raw materials such as fatty alcohols of Al‐Ceder oil. Mixed fatty acids were isolated from Al‐Ceder oil by hydrolysis; both saturated and unsaturated fatty acids were isolated from the mixed fatty acids. The methyl esters of mixed fatty acid, saturated and unsaturated acids of Al‐Cedre oil were subjected to reduction with (LiAlH4) to give the corresponding fatty alcohols. The products of the reduction process were saponified and the hydroxyl values were estimated to further confirm the reduction occurrence. The acrylate esters were synthesized by esterification of acrylic acid with fatty alcohols of C_16:0, C_18:0, C_18:1, and C_18:2 mixed saturated, mixed unsaturated and mixed fatty acids of Al‐Cedre oil, respectively. This esterification was followed by addition of NaHSO₃ to form bisulfite adducts. The structures of the prepared surfactants were characterized by IR and ¹HNMR spectroscopy. A series of useful surface parameters, stability towards acids and base hydrolysis and calcium stability have been determined.     

High performance liquid chromatography and glass capillary gas chromatography of geometric and positional isomers of long chain monounsaturated fatty acids

Positional and geometrical isomers of monounsaturated long chain fatty acids were analyzed by the combination of high performance liquid chromatography (HPLC) and glass capillary gas chromatography (GC). A preparative group separation ofcis andtrans isomers of the monounsaturated fatty acid methyl esters was achieved according to chain length by reversed-phase HPLC, and using a highly sensitive interference refractive index detector. After collection of the different fractions containingcis andtrans forms of the monounsaturated fatty acid methyl esters, the fractions were analyzed for their content of positional isomers using glass capillary GC with Silar-5 CP as stationary phase. The preparative step in the HPLC was also used analytically for the determination of the ratio between thecis andtrans monounsaturated fatty acids. A comparison was made between the results obtained with the HPLC technique and the results of a GLC technique with a packed OV-275 column. There was a good correlation between the 2 techniques with a tendency to highertrans values with the HPLC technique (4%). It was shown with reference substances that 18∶1ω6-cis to ω11-cis and 18∶1ω5-trans to ω12-trans, the most common monounsaturated fatty acid isomers in partially hydrogenated vegetable oils, could be almost quantitatively recovered in the HPLC step. Most of the individual positional isomers of monounsaturated fatty acids of varying chain length could be separated and determined in the glass capillary GC step with the exception of those isomers containing the double bond in a relatively high ω-position. The relative standard deviation of the technique as determined with reference substances was better than 4%. The described technique was applied to the analysis of the isomeric monounsaturated fatty acid content in partially hydrogenated vegetable and marine oils, and about 5 samples a day could be executed. Part of this work has been presented at the ISF/AOCS World Congress, New York (1980)JAOCS 58, (4), 1981, abstr. no. 184.     

Purification of oleic acid,methyl oleate,and oleyl alcohol for use as chemical intermediates

Summary 1. Oleic acid, methyl oleate, and oleyl alcohol of high purity (93 to 96%) were prepared from readily available and inexpensive commercial materials in 65 to 70% yields by fractional distillation and a single low-temperature fractional crystallization. 2. In the fractional distillation of red oil and its methyl esters, lower fractions amounting to about 20% of the starting material were obtained. These are suggested for use in soap manufacture. 3. A fraction containing more than 50% linoleic acid was obtained from the C-18 fraction of red oil by fractional crystallization. This fraction amounted to about 20% of the total starting material and had approximately the same percentage composition of fatty acids as several important semi-drying oils. This paper was presented at the meeting of the American Oil Chemists Society, held in Chicago, on October 7, 1943.     

Fatty Acid Specificity of Candida cylindracea Lipase

Candida cylindracea lipase (SIGMA) was tested against triglycerides (TG) and wax esters (WE) of marine origin as substrates. Under the same conditions, wax esters were hydrolysed at a lower rate than the triglycerides. The C₁₄ to C₁₈ saturated and monounsaturated fatty acids were preferentially hydrolysed whereas the longer chain monoenes (20:1 and 22:1) and particularly the polyunsaturated fatty acids (18:4,20:5 and 22:6) were resistant to the hydrolysis in triglycerides as well as in wax esters. No specificity was demonstrated for the fatty alcohols in the wax esters.     

Fatty acids of cows' milk. A. Techniques employed in supplementing gas-liquid chromatography for identification of fatty acids

Milk fat methyl esters were subjected to distillation and silicic acid column chromatography to provide fractions of less complexity for gas-liquid chromatographic analysis. It was still necessary however to employ supplemental techniques for identification. Chromatograms were obtained with polyester columns of different polarity on all the fractions and necessary reference samples. While many of the components were identified in the usual way by plots of relative retention time versus number of carbon atoms, iodine values for total unsaturation and ultraviolet spectrophotometry for conjugated and nonconjugated polyunsaturated acids were essential for positive identification of some components. Similarly, examination by infrared spectrophotometry confirmed the presence or absence of conjugated diene ascis-trans, trans-trans or both. Isolatedtrans or terminal double bonds were also determined in this way. Gas-liquid chromatograms of some fractions showed incompletely resolved peaks attributable to the presence of methyl esters of odd-carbon atom, branched-chain, and unsaturated acids. Hydrogenation and rechromatographing provided more positive determination of the structure of these components. Further confirmation of identity of some peaks on the chromatogram was achieved by collection of the appropriate fractions and examination of the collected material. At least 60 fatty acids were identified, including several not previously reported, such as odd-numbered carbon chain length monoethenoid acids from C₁₅ to C₂₃. Presented at the 53rd Meeting of the American Oil Chemists' Society, October 17–19, 1960, New York. Eastern Utilization Research and Development Division, Agricultural Research Service, United States Department of Agriculture.