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.     

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.     

Fractional vacuum distillation of herring oil methyl esters

Methyl esters of a Canadian Atlantic herring oil containing 62% monoethylenic fatty acids were subjected to batch fractional distillation under vacuum on a pilot plant scale, to study the feasibility of fractionating fatty acid esters of marine oils of low iodine value into monounsaturated fractions with increased commercial value for industrial chemical uses. A total of 64 methyl ester fractions were collected and analyzed by gas liquid chromatography. Recoveries of the major saturated and monounsaturated acids were close to 100%, and some fractions contained over 90% of the desired 22:1 long chain monounsaturated acids. The short chain polyunsaturated acids were recovered in good yields, but the long chain highly unsaturated acids were recovered in yields of 60% or less due to oxidative and thermal decomposition in the particular apparatus employed. If small amounts of unsaturated acids are acceptable, fractional distillation of low iodine value marine oils could inexpensively supply fractions with high concentrations of methyl esters of longer chain (C₂₀ and C₂₂) monounsaturated and shorter chain (C₁₄) saturated acid or (C₁₆) saturated-monounsaturated acid mixture.     

Effect of Different Frying Methods on the Total <Emphasis Type="Italic">trans</Emphasis> Fatty Acid Content and Oxidative Stability of Oils

The main objective of this study was to determine the effect of different frying oils and frying methods on the formation of trans fatty acids and the oxidative stability of oils. Sunflower, canola and commercial frying oils, the most commonly used oils for frying potatoes in the fast food industry, were used as the frying medium. The value for total polar compounds was highest when commercial frying oil was used in the microwave oven (22.5 ± 1.1). The peroxide value, as an indicator of oil oxidation, was lowest for microwave oven frying (2.53 ± 0.03). The K₂₃₂ and K₂₇₀ values were 0.41 ± 0.04 and 0.18 ± 0.02, respectively, for commercial frying oil in the microwave oven. The lowest free fatty acid content was recorded for the commercial frying oil used in the deep‐fat fryer at 190 °C. The highest iodine value was measured for sunflower oil used in the deep‐fat fryer (148.14 ± 0.07), indicating a greater degree of unsaturation. The lowest trans fatty acid value was recorded for sunflower oil in the microwave oven (0.17 ± 0.05), with a higher overall amount of total trans fatty acids observed for oils after frying in the electrical deep‐fat fryer compared to the microwave. Sunflower oil was favourable for both frying methods in terms of the trans fatty acid content.     

Chloramine T with iodine: A new reagent to determine the iodine value of edible oils

Chloramine T (N-chloro-p-toluenesulfonamide sodium salt) and iodine (2:1, w/w) in carbon tetrachloride and acetic acid (1:1, vol/vol), referred to as reagent (I) was found to be effective for the determination of Iodine value of edible oils. Reagent (I) reacted quantitatively with the double bonds of oils of known weight. The reagent left unreacted after 20–25 min was titrated against standard sodium thiosulfate solution (0.04 M) in presence of potassium iodide (10%, 5 mL). The difference in volume of sodium thiosulfate solution consumed by reagent (I) without and with oil was a basis to calculate the iodine value of oils used. The iodine values of different oils were also determined separately following the standard procedure of Wijs, and calculated iodine value was obtained from the gas chromatographic profile of fatty acids. The iodine value obtained by the new method was in agreement with the results of the standard methods. The results obtained indicate that the method could be a complementary or an alternative to the Wijs method.     

Chloramine T with iodine: A new reagent to determine the iodine value fo edible oils

Chloramine T (N-chloro-p-toluenesulfonamide sodium salt) and iodine (2:1, w/w) in carbon tetrachloride and acetic acid (1:1, vol/vol), referred to as reagent (I) was found to be effective for the determination of Iodine value of edible oils. Reagent (I) reacted quantitatively with the double bonds of oils of known weight. The reagent left unreacted after 20–25 min was titrated against standard sodium thiosulfate solution (0.04 M) in presence of potassium iodide (10%, 5 mL). The difference in volume of sodium thiosulfate solution consumed by reagent (I) without and with oil was a basis to calculate the iodine value of oils used. The iodine values of different oils were also determined separately following the standard procedure of Wijs, and calculated iodine value was obtained from the gas chromatographic profile of fatty acids. The iodine value obtained by the new method was in agreement with the results of the standard methods. The results obtained indicate that the method could be a complementary or an alternative to the Wijs method.     

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.     

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.     

The question of differences between iodine numbers of coconut oil and of the corresponding soapstock fatty acids

Summary Experiments have been made on coconut oil from pure endosperm, pure testa, and normal mixtures of the two. These experiments have shown that the spread in iodine value between refined coconut oil and the fatty acids found on the corresponding soapstock are greater than can be accounted for by the proportion of testa oil present in extracted whole crude oils. Furthermore the iodine value of the free fatty acid fraction of pure endosperm oils was found to be higher than that of the combined fatty acids in the same oils by an amount which varied inversely as the degree of hydrolysis which had occurred in the oil. From this it appears that preferential hydrolysis plays an important part in the production of coconut oil soapstock having higher iodine values than those of the corresponding refined oils. Attention is also called to some European publications which deal with this question and to the possibility that molds may be involved through their ability to decompose short chain acids to ketones.     

Effects of processing on oxidative stability of sesame oil extracted from intact and dehulled seeds

Oxidative stability of oils extracted from intact and dehulled sesame seeds was determined by monitoring changes in fatty acid composition, iodine value (IV), peroxide value (PV), conjugated diene (CD), para-anisidine value (p-AV), and 2-thiobarbituric acid (TBA) value and by nuclear magnetic resonance spectroscopy after storage under Schaal oven conditions at 65°C for up to 35 d. The oils from coated seeds were more stable, as reflected in PV, CD, p-AV and TBA values, than those extracted from dehulled seeds after roasting at 200°C, steaming at 100°C, roasting at 200°C plus steaming, or microwaving at 2450 MHz, except for TBA values of oil from microwaved seeds. After 35 d of storage at 65°C, the CD, p-AV, and TBA values of extracted oil from dehulled microwaved seeds were 17.72, 10.20, and 1.22, respectively, while those of their coated counterparts were significantly (P<0.05) different at 14.20, 16.47, and 1.26, respectively. Few significant changes were evident in the fatty acid composition of oil obtained from either coated and dehulled seeds subjected to different treatments. Nuclear magnetic resonance analyses found that R_ao (aliphatic to olefinic protons) and R_ad (aliphatic to diallylmethylene protons) ratios increased steadily over the entire storage period, which indicated progressive oxidation of unsaturated fatty acids.     

Characterization of Aromatherapy Massage Oils Prepared from Virgin Coconut Oil and Some Essential Oils

The aim of this study was to characterize aromatherapy massage oils prepared from virgin coconut oil (VCO) and some essential oils. VCO extracted from fresh coconut endosperm by a centrifugation method, which was the most effective method to prepare VCO, was composed mainly of saturated fatty acids, in particular myristic acid. Three essential oils (lemon, eucalyptus and lavender oils) at concentrations of 1, 3 and 5% w/w were blended with the VCO to prepare massage oils. Physical and chemical properties as well as microbial analysis of the massage oils were assessed to evaluate quality characteristics of the preparations. Results showed that types and concentrations of essential oils used somewhat affected viscosity, refractive index and three chemical characteristics (acid, peroxide, and iodine values) associated with oxidative stability of the massage oils. Generally the rank order of acid, peroxide and iodine values of the freshly prepared massage oils appeared to be lemon oil > lavender oil > eucalyptus oil. The results of a accelerated storage stability study (45 °C, 4 months) clearly showed a dramatic increase in both acid and peroxide values of VCO and the blended massage oils compared to initial values, whereas the iodine values of these preparations decreased slightly. The plain VCO and the blended massage oils did not exhibit antimicrobial activity on the test microorganisms and were free from microbial contamination.     

Seed oils from cassia fistula,C. Occidentalis,and C. Tora (Indian varieties)

Summary Fatty acids from oils of Indian varieties ofC. fistula, C. occidentalis, andC. tora were fractionated by the lead salt-alcohol and methyl ester distillation methods. Compositions were calculated from the iodine values and saponification equivalents of the ester fractions. Identities of saturated acids were established by determining the properties of the recrystallized acids. Unsaturated acids were identified as the bromo-and hydroxy-derivatives. Cassia fistula, C. occidentalis, andC. tora oils were found to contain the following percentages of fatty acids, respectively: palmitic, 16.0, 19.7, 23.5; lignoceric, 5.2, 4.3, 3.4; oleic, 30.7, 31.6, 28.1; and linoleic, 48.1, 38.1, 45.0. In addition,C. occidentialis oil contained 6.3% of linolenic acid. Chrysophanic acid was isolated in yield of 0.6% fromC. tora oil, but only traces were obtained fromC. occidentalis oil.     

Electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. Sensory and compositional characteristics of low Trans soybean oils

Soybean oils were hydrogenated either electrochemically with Pd at 50 or 60°C to iodine values (IV) of 104 and 90 or commercially with Ni to iodine values of 94 and 68. To determine the composition and sensory characteristics, oils were evaluated for triacylglycerol (TAG) structure, stereospecific analysis, fatty acids, solid fat index, and odor attributes in room odor tests. Trans fatty acid contents were 17 and 43.5% for the commercially hydrogenated oils and 9.8% for both electrochemically hydrogenated products. Compositional analysis of the oils showed higher levels of stearic and linoleic acids in the electrochemically hydrogenated oils and higher oleic acid levels in the chemically hydrogenated products. TAG analysis confirmed these findings. Monoenes were the predominant species in the commercial oils, whereas dienes and saturates were predominant components of the electrochemically processed samples. Free fatty acid values and peroxide values were low in electrochemically hydrogenated oils, indicating no problems from hydrolysis or oxidation during hydrogenation. The solid fat index profile of a 15∶85 blend of electrochemically hydrogenated soybean oil (IV=90) with a liquid soybean oil was equivalent to that of a commercial stick margarine. In room odor evaluations of oils heated at frying temperature (190°C), chemically hydrogenated soybean oils showed strong intensities of an undesirable characteristic hydrogenation aroma (waxy, sweet, flowery, fruity, and/or crayon-like odors). However, the electrochemically hydrogenated samples showed only weak intensities of this odor, indicating that the hydrogenation aroma/flavor would be much less detectable in foods fried in the electrochemically hydrogenated soybean oils than in chemically hydrogenated soybean oils. Electrochemical hydrogenation produced deodorized oils with lower levels of trans fatty acids, compositions suitable for margarines, and lower intensity levels of off-odors, including hydrogenation aroma, when heated to 190°C than did commercially hydrogenated oil.     

Cyclopropenoid fatty acid content and fatty acid composition of crude oils from twenty-five varieties of cottonseed

The cyclopropenoid acid content of oils extracted from 22 commercial varieties and 3 botanical species of cottonseed have been determined. The malvalic acid content determined by HBr titration varied from a low of 0.56% to a high of 1.17%. Iodine values of the oils ranged from 96.8 to 111.6 No definite correlation could be established between iodine value and malvalic acid content. Equations for regression lines for the major acids have been calculated from plots of fatty acid composition vs. iodine value. The high degree or correlation suggests that for commercial oils the fatty acid composition can be estimated from the iodine value. Oils of the 3 experimental types of different species showed wide variations in fatty acid composition and represented many of the maximum and minimum values reported. So. Utiliz. Res. Dev. Div., ARS, USDA. ARS, USDA.     

Chemical studies on corn embryos infected by various fungi

The occurrence of various fungi in corn kernels obtained from eight localities in Egypt in two successive years was studied. Values for refractive index, color, acid value, saponification value, iodine value, peroxide value and unsaponifiable matter content of oils extracted from corn embryos that were deliberately infected by various fungi were compared to those for oil extracted from healthy embryos. Spectrometric analyses (UV, visible and IR) were done to deduce differences in the functional groups of the oils. Corn oil extracted from embryos infected with various fungi contained the same lipid classes as the oil extracted from healthy embryos. Contents of mono- and diglycerides and free fatty acids were much smaller for the oil extracted from healthy embryos. The fatty acid and unsaponifiable compositions of oils were studied by gas liquid chromatography. The fatty acid composition of corn oil extracted from infected embryos showed that some new and short-chain fatty acids had appeared and that some of the 18:2 was converted to 18:0. Analysis of the hydrocarbon fraction of the unsaponifiables showed also that some new compounds had appeared and others disappeared. The sterols were greatly influenced by the fungi and the ratio between different sterols might be used to characterize the effect of fungi. Aflatoxin B₁ content of oil extracted from corn embryos infected byA. flavus was 300 μg/kg.     

Fatty acid methodology for heated oils

Criticisms have been voiced concerning the methods employed for determining the fatty acid composition of vegetable oils used in processing of fried foods. In the present study seveveral different vegetable oils were heated under standardized conditions, at frying temperatures and under air, for various periods of time, and then subjected to analyses for fatty acid composition. The methods employed were: UV spectrophotometry; gas-liquid chromatography (GLC) employing either normalization of the peak areas, direct standards or internal standards; and the enzymic, lipoxidase procedure. The present findings confirm that the drop in iodine value is a good approximation of the reduction of polyunsaturated fatty acids in heated oils. In evaluating liquid nonhydrogenated vegetable oils that had been subjected to heat abuse under standard conditions, all of the analytical methods for the estimation of fatty acid composition, with the exception of normalization of GLC peak areas, give substantially the same results. With hydrogenated vegetable oils, the analytical methods provide values which differ significantly among themselves. Evidence was also presented to show that the quantity of material retained on the gas chromatographic column is directly related to the loss of polyunsaturates for oils heated under controlled conditions. For evaluation of oils from frying operations, the preferred method is the GLC method utilizing internal standards if the purpose is the determination of total polyunsaturated fatty acids. However, if the study being made involves a question of nutritional value, then the measurement of the essential fatty acids by the lipoxidase enzymic procedure is the more valid method for evaluation, of heated oils. Presented at the AOCS Meeting, New Orleans, April 1970.     

Comparison of Soybean and Cottonseed Oils upon Hydrogenation with Nickel,Palladium and Platinum Catalysts

There is current interest in reducing the trans fatty acids (TFA) in hydrogenated vegetable oils because consumption of foods high in TFA has been linked to increased serum cholesterol content. In the interest of understanding the TFA levels, hydrogenation was carried out in this work on soybean oil and cottonseed oil at two pressures (2 and 5 bar) and 100 °C using commercially available Ni, Pd, and Pt catalysts. The TFA levels and the fatty acid profiles were analyzed by gas chromatography. The iodine value of interest is ~70 for all-purpose shortening and 95–110 for pourable oil applications. In all cases, higher hydrogen pressures produced lower levels of TFA. In the range of 70–95 iodine values for the hydrogenated products, the Pt catalyst gave the least TFA, followed closely by Ni, and then Pd, for both oils. For all three catalysts at 2- and 5-bar pressures and 70–95 iodine values, cottonseed oil contained noticeably less TFA than soybean oil; this is probably because cottonseed oil contains a lower total amount of olefin-containing fatty acids relative to soybean oil. Approximate kinetic modeling was also done on the hydrogenation data that provided additional confirmation of data consistency.     

Estimation of cetane index for esters of fatty acids

Cetane indexes have been calculated for the esters of the individual saturated fatty acids in the C₈-C₂₄ range plus palmitoleic, oleic, linoleic, and linolenic acids. Two methods were used for these calculations: ASTM 976 and a method involving simultaneous equations relating the experimentally determined cetane numbers for several transesterified oils and the fatty acid compositions of the oils. Cetane indexes calculated according to ASTM 976 produced values which were too low for ester mixtures high in saturated acids and low in polyunsaturated acids, and were somewhat high for ester mixtures high in polyunsaturated acids. When cetane indexes calculated according to the simultaneous equation method were applied to the fatty acid mixtures, the agreement with those experimentally determined was approximately the error of determination of the cetane number.     

Preparation of Omega-3 PUFA Concentrates from Fish Oils via Urea Complexation

The effect of weight ratio of urea to fatty acids and the urea-fatty acid adduct crystallization temperature on the enrichment of eicosapentaenoic acid from marine oil fatty acids was studied. The optimum ratio of urea to fatty acids was found to be 3 : 1 for laboratory scale preparations and the optimum temperature for the formation of urea-fatty acid adduct was 1°C. At very low temperatures (?12, ?18, ?35°C) the recovery efficiency for EPA was reduced. Using these optimum values, enrichment of EPA and other n-3 polyunsaturated fatty acids via urea complexation was carried out on a pilot plant scale in a variety of North Atlantic and North Pacific fist oils and a seal oil. Irrespective of hte type of starting oil, all the oils gave a concentrate with 69–85% total n-3 PUFA with an overall yield of 17–20%. Menhaden is clearly an ideal oil for preparation of EPA concentrate, as the starting oil usually has a higher proportion of EPA to DHA than most of the other commercial fish oils.     

Evaluation of physicochemical changes in cooking oil during heating

Rice bran oil and double fractionated palm olein (DF palm olein) were heated at 180 C for 50 hr to measure lipid deterioration in the oils. Free fatty acid content of both oils increased during heating; however, iodine value and smoke point decreased. Solid fat contents of both oils were unaffected by heating time. Cloud point of rice bran oil was much lower than that of palm olein. Color of oils changed gradually to dark brown from light yellow with increased heating time. Absolute content of polyunsaturated fatty acid, such as linoleic acid, reduced more than that of monounsaturated fatty acid, such as oleic acid, in both oils. In both oils, iodine value correlated very well with linoleic acid content, with correlation coefficient higher than 0.96.