High-temperature stabilities of oils from soybeans that lack lipoxygenases

Oils from normal or low-linolenic acid (18:3) soybeans that lack lipoxygenase (LOX) 2 or LOX 2 plus LOX 3 activities were evaluated for their stability during frying and for oxidative stability in bread cubes stored after frying. Soybean oils were extracted by a pilot-plant system and were refined, bleached, and deodorized in the laboratory. Citric acid was added to oils during the cool-down stage of deodorization. Two replications, separated at the point of conditioning, were evaluated for each genotype. Each sample (250 g) was heated to 180±5°C in a minifryer. Bread cubes were fried at the beginning of heating and after 20 h of heating. Heating of the oils was continued for 10 h each day for three consecutive days. Soybean oils with low 18:3 contents were significantly (P ≤ 0.05) more stable, as measured by conjugated dienoic acids and polymer values, than were oils with normal 18:3 contents. Low-LOX 2 or low-LOX 2 + 3 activity had no effect on peroxide values of soybean oils extracted from bread cubes. Sensory evaluation did not differentiate between oils that contained low or high 18:3 amounts or among oils from beans that lacked different LOX enzymes.     

Factors affecting the content of tocopherol in soybean oil

The state of soybeans prior to extraction affected the tocopherol content of crude soybean oils. Soybean flakes with a thickness of 0.16–0.33 mm had higher extracted oil yield but a slightly lower tocopherol content of the oils than did cracked beans and thicker bean flakes. Highmoisture content and long storage of soybeans resulted in lower tocopherol content in the crude oils, with moisture content being more important than storage time at decreasing the tocopherol content of oils. Soybean oil from stored beans with 15±1% moisture content led to a more significant decrease in the tocopherol content than did oil from stored beans with low (12%) or high (18%) moisture contents. Soybean flakes contaminated with oxidized oil had a significant effect on the decrease of the tocopherol content in crude oils. The high amount of phospholipids in crude soybean oil might result in a smaller decrease in the tocopherol content of oil during heating.     

Low-linolenic acid soybean oil—Alternatives to frying oils

Oil was hexane-extracted from soybeans that had been modified by hybridization breeding for low-linolenic acid (18∶3) content. Extracted crude oils were processed to finished edible oils by laboratory simulations of commercial oil processing procedures. Oils from three germplasm lines N83-375 (5.5% 18∶3), N89-2009 (2.9% 18∶3) and N85-2176 (1.9% 18∶3) were compared to commercial unhydrogenated soybean salad oil with 6.2% 18∶3 and two hydrogenated soybean frying oils, HSBOI (4.1% 18∶3) and HSBOII (<0.2% 18∶3). Low-18∶3 oils produced by hybridization showed significantly lower room odor intensity scores than the commercial soybean salad oil and the commercial frying oils. The N85-2176 oil with an 18∶3 content below 2.0% showed no fishy odor after 10 h at 190°C and lower burnt and acrid odors after 20 h of use when compared to the commercial oils. Flavor quality of potatoes fried with the N85-2176 oil at 190°C after 10 and 20 h was good, and significantly better at both time periods than that of potatoes fried in the unhydrogenated oil or in the hydrogenated oils. Flavor quality scores of potatoes fried in the N89-2009 oil (2.9% 18∶3) after 10 and 20 h was good and equal to that of potatoes fried in the HSBOI oil (4.1% 18∶3). Fishy flavors, perceived with potatoes fried in the low-18∶3 oils, were significantly lower than those reported for potatoes fried in the unhydrogenated control oil, and the potatoes lacked the hydrogenated flavors of potatoes fried in hydrogenated oils. These results indicate that oils with lowered linolenic acid content produced by hybridization breeding of soybeans are potential alternatives to hydrogenated frying oils.     

Oxidative and flavor stabilities of soybean oils with low-and ultra-low-linolenic acid composition

The effects of linolenic acid (18∶3) concentration, combined with TBHQ addition, temperature, and storage time, on the oxidative and flavor stabilities of soybean oils (SBO) were evaluated. During storage under fluorescent light at both 21 and 32°C, the SBO with ultra-low-18∶3 concentration (1.0%, ULSBO) generally had greater oxidative stability than did SBO with low-18∶3 concentration (2.2%, LLSBO). The ULSBO had about half the p-anisidine value of LLSBO throughout storage. Although the ULSBO initially had significantly greater PV and poorer (lower) sensory scores for overall flavor quality than did LLSBO, significant differences disappeared with storage. The ULSBO had a lower content of polar compounds and greater oil stability indices than did LLSBO when TBHQ was present. All oils were more oxidatively stable with TBHQ addition, but the TBHQ addition did not result in improved flavor stability early in storage. In all tests, oils stored at 32°C were less stable than oils stored at 21°C. The TBHQ had a better antioxidant capacity when the 18∶3 concentration was lower. The retardation effect of TBHQ on lipid oxidation and the improved stability of ULSBO over LLSBO were more easily detected when the storage temperature was higher.     

The effect of dietary fatty acid balance on myocardial lesions in male rats

Three hundred (experiment I) and 350 (experiment II) weanling, 3-week-old male Sprague-Dawley rats weighing between 40–50 g were randomly assigned two per cage and 50 per dietary treatment to study the effect of dietary fatty acid balance on myocardial lesions. The following oils were tested: Experiment I.Brassica napus var. Tower rapeseed oil [Tower RSO, 1974 cultivar and 1975 cultivar, each containing 0.3% erucic (22∶1) acid];B. napus var. Zephyr RSO containing 0.9% 22∶1; corn oil; olive oil; and soybean oil. Experiment II.B. napus var. Tower RSO (1974 cultivar), olive oil, soybean oil, and the following oils to which was added the indicated level of free 22∶1; Tower +0.5% 22∶1; Tower +5.6% 22∶1; olive oil +4.4% 22∶1; soybean oil +5.7% 22∶1. In each case the oils were incorporated in a semisynthetic diet at a level of 20% by weight. Heart and heart lipid weights of rats fed the different oils did not differ statistically from each other. Fatty acid analyses of heart lipids revealed that the fatty acid composition of the cardiac lipids reflected that of the diet fed. In experiment I, there was a definite but significantly lower incidence (P<0.01) and severity (P<0.01) of heart lesions in rats fed control oils (corn, olive, soybean) than in rats fed rapeseed oils. Also, in experiment II, a definite but lower incidence and severity of heart lesions occurred in rats fed control oils (soybean, olive) compared to rats fed Tower RSO or this oil with added free 22∶1. Adding 22∶1 to an oil naturally high in 18∶3 (soybean) did not alter the incidence of heart lesions, whereas adding 22∶1 to an oil naturally high in 18∶1 (olive) increased significantly (P<0.01) both the incidence and severity of heart lesions. Thus, it appears that the background incidence of heart lesions that are found in the rat in any case, and which are increased by rapeseed oil feeding, is caused by the imbalanced fatty acid composition of the oil for the growing rat, i.e. high monoenes (18∶1, 20∶1, and 22∶1) and high 18∶3 and is not only due to the presence of excess 18∶3. Contribution No. 706, Animal Research Institute.     

Hematological and lipid changes in newborn piglets fed milk replacer diets containing vegetable oils with different levels of n−3 fatty acids

To test if linolenic acid (18∶3n−3) from vegetable oils would affect bleeding times and platelet counts in new-borns, piglets were used as a model fed milk replacer diets containing 25% (by wt) vegetable oils or oil mixtures for 28 d and compared to sow-reared piglets. The oils tested included soybean, canola, olive, high oleic sunflower (HOAS), a canola/coconut mixture and a mixture of oils mimicking canola in fatty acid composition. All piglets fed the milk replacer diets showed normal growth. Bleeding times increased after birth from 4–6 min to 7–10 min by week 4 (P<0.001), and were higher in pigs fed diets containing 18∶3n−3, as well as in sowreared piglets receiving n−3 polyunsaturated fatty acids (PUFA) in the milk, as compared to diets low in 18∶3n−3. Platelet numbers increased within the first week in newborn piglets from 300 to 550×10⁹/L, and remained high thereafter. Milk replacer diets, containing vegetable oils, generally showed a transient delay in the rise of platelet numbers, which was partially associated with an increased platelet volume. The oils showed differences in the length of delay, but by the third week of age, all platelet counts were >500×10⁹/L. The delay in rise in platelet counts appeared to be related to the fatty acid composition of the oil, as the effect was reproduced by a mixture of oils with a certain fatty acid profile, and disappeared upon the addition of saturated fatty acids to the vegetable oil. There were no alterations in the coagulation factors due to the dietary oils. Blood plasma, platelets and red blood cell membranes showed increased levels of 18∶3n−3 and long-chain n−3 PUFA in response to dietary 18∶3n−3. The level of saturated fatty acids in blood lipids was generally lower in canola and HOAS oil-fed piglets as compared to piglets fed soybean oil or reared with the sow. The results suggest that consumption of milk replacer diets containing vegetable oils rich in 18∶3n−3 does not represent a bleeding risk, and that the transient lower platelet count can be counterbalanced by the addition of saturated fatty acids to the vegetable oils.     

Influence of partially hydrogenated vegetable and marine oils on lipid metabolism in rat liver and heart

Partially hydrogenated marine oils containing 18∶1-, 20∶1- and 22∶1-isomers and partially hydrogenated peanut oil containing 18∶1-isomers were fed as 24–28 wt % of the diet with or without supplement of linoleic acid. Reference groups were fed peanut, soybean, or rapeseed oils with low or high erucic acid content. Dietary monoene isomers reduced the conversion of linoleic acid into arachidonic acid and the deposition of the latter in liver and heart phosphatidylcholine. This effect was more pronounced for the partially hydrogenated marine oils than for the partially hydrogenated peanut oil. The content oftrans fatty acids in liver phospholipids was similar in groups fed partially hydrogenated fats. The distribution of various phospholipids in heart and liver was unaffected by the dietary fat. The decrease in deposition of arachidonic acid in rats fed partially hydrogenated marine oils was shown in vitro to be a consequence of lower Δ6-desaturase activity rather than an increase in the peroxisomal β-oxidation of arachidonic acid. The lower amounts of arachidonic acid deposited may be a result of competition in the Δ6-desaturation not only from the C22-and C20-monoenoic fatty acids originally present in the partially hydrogenated marine oil, but also from C18- and C16-monoenes produced by peroxisomal β-oxidation of the long-chain fatty acids. Part of this work was presented at the ISF-AOCS Congress, New York City, 1980.     

Oxidative stabilities of soybean oils with elevated palmitate and reduced linolenate contents

Oils from soybean lines, developed to contain different amounts of palmitate (16:0) and linolenate (18:3), were evaluated for oxidative stability. Oils were extracted in the laboratory from the soybean seeds and refined, bleached, and deodorized. Two replications, separated at the point of conditioning, were evaluated for each genotype, including Hardin 91 (normal beans), P9322 (10.6% 16:0 and <2.6% 18:3), A91-282036 (26.3% 16:0 and 9.8% 18:3), and HPLL (23.2% 16:0 and 3.5 % 18:3). Elevating 16:0 and/or lowering 18:3 increased the oxidative stability of soybean oils as measured by peroxide values. Soybean oils with elevated 16:0 had higher solidification temperatures than did oils with normal 16:0 content, and soybean oils with low 18:3 content had higher solidification temperatures than did oils with normal 18:3 contents.     

Fatty acids and oil content in white lupin seed as affected by production practices

Characteristics of the seed oil of white lupin (Lupinus albus L.), a potential alternative winter crop in the mid-Atlantic region of the United States, are not well established. Replicated experiments were conducted during the 1998–1999 and 1999–2000 growing seasons with a determinate and an indeterminate cultivar to characterize oil and FA in lupin seed in relation to production practices. The experiments were planted in early October, late October, and mid-November using row spacings of 0.3, 0.6, and 0.9 m at each planting time. Seeds from the planting date of early October had significantly (P<0.05) higher oil content than the later plantings (late October and mid-November). A closer row spacing (0.3 m) also had significantly (P<0.05) higher oil content than the wider row spacing (0.9 m). Planting data effects on FA content were significant for some FA, but row spacing did not affect FA contents. Oil content in the seed varied from 7.2 to 8.2% (w/w). The oil from white lupin seed contained FA in the order of 18∶1>18∶2> 18∶3>16∶0>20∶1>22∶1>22∶0>18∶0>24∶0>20∶0. The saturated FA/unsaturated FA ratio in lupin oil was 0.14. White lupin seed contained higher contents of oil and FA than literature values for seed of navy, kidney, and pinto beans.     

Effects of soybean pretreatments on crude oil quality

The effects of soybean pretreatments, including infrared (IR) radiation, oven toasting, microwave heating and live steam treatment on crude oil quality were investigated. Free fatty acid, oxidation value, carbonyl value and tocopherol content were used to monitor crude soybean oil quality. All soybean pretreatments were effective in improving the quality of oils from 15 and 18% moisture beans. Based on the analyses, recommended treatments are 3–4 min for IR at 220V–250W; 1 min for microwave heating at 650 W–2450 mHz; 1–1.5 min for steam heating; and 100–120°C, 30 min for oven toasting. Heat treatment of high-moisture soybeans before extraction yielded crude oil with a lower content of phosphatidic acid as compared to that of the untreated beans.     

Molecular markers associated with linolenic acid content in soybean

An altered FA profile with decreased linolenic (18∶3) acid in soybean germplasm was developed by crossing N97-3708-13, a soybean line with reduced 18∶3 (<5.4%) and ‘Anand’, a normal soybean cultivar (9.7% 18∶3). The resulting recombinant inbred lines are promising because they may promote healthier oil with improved oxidative stability and flavor. The objective of this study was to utilize the population N97-3708-13 × Anand to identify simple sequence repeat (SSR) markers associated with 18∶3 content. Two markers, Satt534 and Satt560, which are located approximately 10 cM apart from each other, near the Fan locus on linkage group B2, were identified as quantitative trait loci significantly associated with 18∶3 content (P=0.001, R ²=0.59, individually). The SSR markers identified in this study should be useful for implementation of marker-assisted selection for low-18∶3 genotypes in soybean breeding programs.     

HPLC analysis of phospholipids in crude oil for evaluation of soybean deterioration

Damage to soybeans due to pre-harvest stress, storage, and export shipment has been related to an increase in the nonhydratable phospholipid content of crude oil. Phospholipids in crude soybean oil extracted from such distressed soybeans have been analyzed by gradient high-performance liquid chromatography. Crude oil was fractionated by solid phase extraction using sequential elution for recovery of phosphatides. High-performance liquid chromatography of the concentrated phospholipids was accomplished on a Lichrosorb Si-60 10 μ column, 250×4.6 mm with ultraviolet detection at 206 nm. A 20-min solvent gradient of 2-propanol/hexane/water (42∶56∶2, 51∶38∶11) gave retention profiles of phospholipid distribution (major subclasses) that changed with impact of stress applied to plant or seed. Soybeans stored at high moisture levels (16% and 20% moisture) for up to 28 days yielded oils having phosphorus contents which decreased in direct relationship to days of storage. Retention profiles were unusable for fractions isolated from oils with phosphorus content below 100 ppm. Data show that during progressive damage, the content of phosphatidylcholine and phosphatidylinositol decreased while the phosphatidic acid content increased. Presented at the Annual American Oil Chemists' Society meeting, May 8–12, 1988, Phoenix, AZ.     

Conifer seeds: Oil content and fatty acid composition

The seed oils from twenty-five Conifer species (from four families—Pinaceae, Cupressaceae, Taxodiaceae, and Taxaceae) have been analyzed, and their fatty acid compositions were established by capillary gas-liquid chromatography on two columns with different polarities. The oil content of the seeds varied from less than 1% up to 50%. Conifer seed oils were characterized by the presence of several Δ5-unsaturated polymethylene-interrupted polyunsaturated fatty acids (Δ5-acids) with either 18 (cis-5,cis-9, 18∶2,cis-5,cis-9,cis-12 18∶3, andcis-5,cis-9,cis-12,cis-15 18∶4 acids) or 20 carbon atoms (cis-5,cis-11 20∶2,cis-5,cis-11,cis-14, 20∶3, andcis-5,cis-11,cis-14,cis-17 20∶4 acids). Pinaceae seed oils contained 17–31% of Δ5-acids, mainly with 18 carbon atoms. The 20-carbon acids present were structurally derived from 20∶1n-9 and 20∶2n-6 acids. Pinaceae seed oils were practically devoid of 18∶3n-3 acid and did not contain either Δ5-18∶4 or Δ5-20∶4 acids. Several Pinaceae seeds had a Δ5-acid content higher than 50 mg/g of seed. The only Taxaceae seed oil studied (Taxus baccata) had a fatty acid composition related to those of Pinaceae seed oils. Cupressaceae seed oils differed from Pinaceae seed oils by the absence of Δ5-acids with 18 carbon atoms and high concentrations in 18∶3n-3 acid and in Δ5-acids with 20 carbon atoms (Δ5-20∶3 and Δ5-20∶4 acids). Δ5-18∶4 Acid was present in minute amounts. The highest level of Δ5-20∶4 acid was found inJuniperus communis seed oil, but the best source of Δ5-acids among Cupressaceae wasThuja occidentalis. Taxodiaceae seed oils had more heterogeneous fatty acid compositions, but the distribution of Δ5-acids resembled that found in Cupressaceae seed oils. Except forSciadopytis verticillata, other Taxodiaceae species are not interesting sources of Δ5-acids. The distribution profile of Δ5-acids among different Conifer families appeared to be linked to the occurrence of 18∶3n-3 acid in the seed oils.     

Occurrence of mixtures of geometrical isomers of conjugated octadecatrienoic acids in some seed oils: Analysis by open-tubular gas liquid chromatography and high performance liquid chromatography

Analytical methods to obtain the detailed compositions of the fatty acids in oils containing more than one conjugated octadecatrienoic acid by open-tubular gas liquid chromatography (GLC) and by reversed-phase high performance liquid chromatography (HPLC) were established. Effective GLC separations ofcis,trans,trans-9,11,13-octadecatrienoic acid (ctt-9,11,13–18∶3),ctc-9,11,13–18∶3,ttc-9,11,13–18∶3,ttt-9,11,13–18∶3,ttc-8,10,12–18∶3, andttt-8,10,12–18∶3 were obtained with an opentubular column coated with the nonpolar liquid phase OV-1 using an instrument having all-glass carrier gas pathways. The HPLC method also gave satisfactory separations for the isomeric conjugated octadecatrienoates on the basis of number of thecis andtrans double bonds. Two or three minor conjugated trienoic acids were found along with the principal conjugated trienoic acid in tung oil, and seed oils of cherry,Prunus sp., Momordica charantia, Trichosanthes anguina, Punica granatum, Catalpa ovata, andCalendula officinalis. The mechanism for the formation of the conjugated trienoic acid mixtures in the seed oils is discussed. TheC. ovata seed oil also containedct andtt-9,12-octadecadienoic acids. Thett isomer is presumed to be a precursor ofttc-9,11,13–18∶3, the main conjugated trienoic acid in this oil.     

Analysis of free and esterified sterols in vegetable oils

In vegetable oils, phytosterols occur as free sterols or as steryl esters. Few analytical methods report the quantification of esterified and free sterols in vegetable oils. In this study, esterified and free sterols were separated by silica gel column chromatography upon elution with n-hexane/ethyl acetate (90∶10 vol/vol) followed by n-hexane/diethyl ether/ethanol (25∶25∶50 by vol). Both fractions were saponified separately and the phytosterol content was quantified by GC. The analytical method for the analysis of esterified and free sterols had a relative standard deviation of 1.16% and an accuracy of 93.6–94.1%, which was comparable to the reference method for the total sterol analysis. A large variation in the content and distribution of the sterol fraction between different vegetable oils can be observed. Corn and rapeseed oils were very rich in phytosterols, which mainly occurred as steryl esters (56–60%), whereas the majority of the other vegetable oils (soybean, sunflower, palm oil, etc.) contained a much lower esterified sterol content (25–40%). No difference in the relative proportion of the individual sterols among crude and refined vegetable oils was observed.     

An investivation of the extraction,refining and composition of oil from winged bean (Psophocarpus tetragonolobus [L.] D.C.)

Eleven winged bean accessions from Thailand were analyzed. Oil content ranged between 15 and 18%. Oleic and linoleic acids were the major fatty acids (62.5–64.5%) together with behenic (12.6–14.4%) and lignoceric acid (2.4–2.8%). Linolenic acid level was low and traces of 15-, 17- and 21-carbon acids (saturated and unsaturated) were found. No parinaric acid was detected. Campesterol, stigmasterol and β-sitosterol were the principal components of the unsaponifiable fraction. The extracted oil had a very low free fatty acid (FFA) content but was not completely liquid below 35 C. The refining of crude winged bean oil is reported. Oil produced by expeller had a strong, beany aroma but a negligible level of gums and a low level of FFA. Degumming and neutralizing were unnecessary; bleaching produced an attractive colored oil free from beany aroma. Crude solvent-extracted oils from whole and decorticated winged beans had appreciable contents of gums and higher FFA contents than expeller-produced oil. Laboratory refining demonstrated the strong interference on bleaching exerted by gums and FFA. Conventional refining by degumming, neutralizing, bleaching and deodorizing, and by physical refining produced high-quality oils having a good color, low FFA level and no taste or smell. The solid/liquid ratio of refined winged bean oil as a function of temperature was found to be unusual. Oil was extracted from whole and decorticated winged beans in a pilot solvent extraction plant designed to simulate a Rotocei. Winged bean flakes were not as mechanically strong as those from soybean but good oil extraction yields were obtained and a meal was produced having an oil content of less than 1% at 10% moisture. Whole winged beans were expelled in a small expeller (throughput 16.8 kg/hr). Cake was produced with a residual oil content of 3.3–5% in a single pass through the expeller.     

Low-palmitic,low-linolenic soybean development

Plant breeding research efforts are currently focused on developing breeding procedures to decrease the saturated FA palmitic acid (16∶0) and the PUFA linolenic acid (18∶3) in U.S. soybean cultivars. Soybean oil with lower 16∶0 may provide cardiovascular benefits to health-conscious consumers, and lower 18∶3 could contribute to better flavor and stability of the oil. The purpose of this study was to determine genetic parameters that indicate the potential for breeding success and to characterize the correlated effect of the incorporation of the modified oil traits on the agronomic and seed quality traits of a soybean breeding population formed from a cross between the soybean cultivar Anand (normal) and germplasm N97-3708-13 (low 16∶0, low 18∶3). Although lines with only one modified oil quality trait (low 16∶0 or 18∶3) are useful as parents, commercial utilization requires productive cultivars with the combination of both oil traits. This paper shows the ease with which they may be combined with seed yield and other traits. Measurements were obtained from 179 F₂ single plants grown in 1999 and 121 F_2∶4 lines grown in replicated plots in 2000. Modified FA lines were developed with ca. 4% 16∶0 and 18∶3, respectively. Very weak positive correlations were found between 16∶0 concentration and seed yield (r=0.12) and between 16∶0 and seed oil concentration (r=0.13). No correlation was found between 18∶3 levels and seed yield, or between 18∶3 levels and seed oil concentration. These results indicate that breeding for reduced 16∶0 and 18∶3 should not have a negative impact on seed yield or oil concentration. 16∶0 and 18∶3 had moderately high heritabilities of 0.65 and 0.73, respectively. This indicates that breeders using low 16∶0, low 18∶3 germplasm in crosses with normal, elite lines can expect to recover low 16∶0 and low 18∶3 in pure line progenies via selection and generation advancement of F₂ individuals that express low levels of these FA.     

Effect of moisture,microwave heating,and live steam treatment on phospholipase D activity in soybeans and soy flakes

The impact of enzyme activity on the nonhydratable phospholipid content of crude soybean oil has been evaluated. A radiochemical method was used to assay phospholipase D activity in whole and flaked soybeans stored under a variety of storage and enzyme inactivating conditions. The crude enzyme was isolated and incubated with a mixture of¹⁴C-labeled and unlabeled phosphatidylcholine. The amount of liberated radioactive choline was used as a measure of enzyme activity. whole soybeans with moisture contents of 8–18% were stored at 40°C and sampled weekly for up to four weeks. Although the enzyme was active in all samples, the optimum moisture content for enzyme activity was about 14%. Flaking and flake thickness were shown to increase phospholipas D activity. At moisture levels above 10%, flakes at .012″ showed about twice the activity of whole beans. As flake thickness was increased, enzyme activity decreased. Whole soybeans with moisture contents of 12–18% were treated by microwave heating under controlled conditions. During the early stages of heating, the enzyme was activated, and then was gradually destroyed by the time the temperature of the beans reached 115–120°C. Approximately 8–10 min of microwave heating was required to completely destroy enzymatic activity. The inactivation of phospholipase D in soyflakes treated with live steam was also evaluated. The enzyme is rapidly destroyed at temperatures of about 110°C. Evaluations of flakes subjected to live steam and whole beans treated by microwave heating to inactivate phospholipase D suggest that heat, moisture and enzyme activity are important factors contributing to the formation of nonhydratable phospholipid in extracted crude oils. Presented at Annual Meeting of the American Oil Chemists' Society, May 3–7, 1989.     

<Emphasis Type="Italic">Trans</Emphasis> FA in sunflower oil at different steps of refining

The contents of total trans FA of sunflower oils at different stages of refining processes were determined by capillary GLC. The contents of 18∶1, 18∶2, and 18∶3 trans acids were 0.22±0.03, 2.31±0.23, and 0.03±0.01%, respectively, in physically refined sunflower oils, and 0.05±0.01, 0.69±0.26, and 0.02±0.01%, respectively, in chemically refined sunflower oils. The total trans FA contents drastically increased at the end of the physical refining process. The total trans FA contents of chemically refined sunflower oils were <1%. Because of the high temperature applied in the last stage of physical refining, the content of total trans FA was higher than in chemically refined sunflower oils. The last-stage conditions should be carefully evaluated to reduce the formation of trans FA during physical refining.