The content and composition of sterols and sterol esters in sunflower and poppy seed oils

The composition and proportion of free sterols and sterol esters in crude sunflower and poppy seed oils were determined, using preparative thin layer chromatography followed by gas chromatography with cholesterol as an internal standard. Free sterols and sterol esters were also isolated in a liquid fraction obtained by low temperature crystallization (−80 C) of the oils and enriched with minor lipid classes. This enrichment procedure provided a liquid fraction suitable for studies of minor components in the oils. However, selectivity towards sterol esters was observed since sterols esterified to very long chain fatty acids (C₂₀–C₂₄) were preferentially retained in the precipitate. The proportions of free and esterified sterols were found to be 0.34 and 0.28%, respectively, in the sunflower oil, whereas the corresponding figures for poppy seed oil were 0.33% and 0.05%. Sunflower oil was characterized by a relatively high percentage of Δ7-sterols, preferentially obtained in the esterified fraction, and by very long chain saturated fatty acids of sterol esters. The sterols in poppy seed oil were composed almost entirely of campesterol, stigmasterol, sitosterol and Δ5-avenasterol, although their percentage distributions were remarkably different in the free and esterified fraction.     

Sterol composition inCoincya (Brassicaceae)

Sterol composition was determined for seed oils and leaf waxes in eleven taxa belonging to the genusCoincya (Brassicaceae) on the Iberian Peninsula (Spain and Portugal). Seed sterols ranged from 1.2 to 6.7%. The major components were sitosterol (42.6–54.6%), campesterol (20.4–33.2%), and brassicasterol (10.8–23.5%). In leaf waxes, the major free sterols were sitosterol (40.9–74.2%), campesterol (9.6–17.0%), and cholesterol (4.6–17.0%). In leaf wax esters, the major sterols were sitosterol (22.2–56.5%), cholesterol (7.3–32.8%), and campesterol (5.8–25.6%). An apparent substitution of brassicasterol in free sterols from the seeds by cholesterol in free sterols from the leaves was observed. There was an increase of cholesterol in sterols from leaf wax esters with respect to free sterols from leaves and seeds. InC. monensis subsp.nevadensis, the composition in sterols from leaf waxes may be an adaptation to low temperatures.     

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.     

Distribution of free and conjugated sterols in orange and tangor juice sacs

Comparative studies of the sterol composition of four sterol fractions, vis., free sterols, sterol esters, sterol glucosides and esterified sterol glucosides, were conducted on the juice sacs of six varieties of oranges and two tangor varieties. The sterols quantified in each fraction were β-sitosterol, campesterol, stigmasterol, cholesterol, 24-ethylidene cholesterol, brassicasterol and 24-methylene cholesterol. Each variety showed its own intrinsic composition for these sterols in the four sterol fractions. So. Market. Nutr. Res. Div., ARS, USDA.     

Free sterols,steryl esters,and lipid phosphorus in needles of scot's pine (Pinus sylvestris L.)

Free sterols, steryl esters, and lipid phosphorus were measured in new (current year) needles of Scot's pine during an annual cycle, and also in one-, two-, and three-year-old needles collected shortly after bud break. Sterols were identified and quantified by capillary gas chromatography and gas chromatography/mass spectrometry. Steryl esters were hydrolyzed enzymatically. Newly emerged needles contained highest amounts of free sterols and lipid phosphorus, probably reflecting increased membrane and organelle production, but low levels of steryl esters. Mature needles contained approximately equal amounts of free and esterified sterols. The molar phospholipid/free sterol ratio was 3∶1 at all the time periods studied. A dramatic increase of steryl esters was observed in the one-, two-, and three-year-old needles at times when new needles emerged. The individual free and esterified sterols were sitosterol, campesterol (presumably together with its C-24 epimer), and cholesterol, at approximately 88, 10, and 2%, respectively. Isofucosterol, an intermediate in sitosterol biosynthesis, was present almost exclusively in newly emerged needles. Esterified sterols contained only trace amounts of isofucosterol. Shifts in favor of cholesterol and 24ζ-methyl cholesterol occurred in the steryl esters during needle differentiation, and saturation grade of esterified fatty acids decreased. In mature needles, the composition of free sterols and steryl esters remained constant throughout the year.     

The Content and Composition of Total,Free, and Esterified Sterols of Lotus Plumule Oil by GC–MS/FID

This study investigated the content and composition of total, free, and esterified sterols of three varieties of lotus plumule oil (Hunan lotus, Jiangxi lotus, and Fujian lotus) using GC–MS/FID. The fatty acid composition of sterol fatty acid esters (SFAE) was also analyzed and compared with that of triglycerides. Results showed that total sterol of lotus plumule oil (12.10–14.21 g/100 g) was higher than that of other plant oils (corn germ oil, 1.11 g/100 g; rapeseed oil, 0.78 g/100 g). No significant difference was found among the total sterol contents of the three types of lotus plumule oils (p > 0.05). Most sterol existed in ester forms (81.8–89.1%) rather than in free forms (8.4–10.1%). β‐Sitosterol (71.4–73.4%), and campesterol (6.2–7.5%) were the predominant fractions of free sterols. β‐Sitosterol (41.3–53.7%) and ?5‐avenasterol (27.1–31.1%) were the predominant fractions of esterified sterols, followed by campesterol (12.1–13.0%) and ?7‐avenasterol (3.4–3.7%). Linoleic acid (63.6–65.8%), oleic acid (8.3–10.4%), and behenic acid (9.0–9.9%) were the main fatty acids of SFAE, which were different from those of triglycerides. The results from this study suggest that lotus plumule oil may be a good resource of SFAE and can be used as a supplemental ingredient in functional foods.     

The Effect of processing on the content and composition of free sterols and sterol esters in soybean oil

The content and composition of free sterols and sterol esters in crude soybean oil and in oils from different stages of two continuous refining systems were determined. The sterols were isolated by preparative thin layer chromatography and analyzed by gas chromatography with cholesterol as an internal standard. The free sterols in one of the degummed oils amounted to 3.1 mg/g and were diminished to 1.8 mg/g oil by the De Laval Short-Mix refining process. The content of free sterols of the other degummed oil was reduced from 3.4 to 1.6 mg/g oil by the Zenith process. The greatest reduction of sterol content was caused by the treatment with bleaching earth. The sterol esters accounted for 0.6 mg/g of the degummed oil, and only very small changes were observed during the processes. However, changes in the composition of fatty acids of the sterol esters were found. These changes might indicate a selective deacylation of sterol esters or an interesterification during the refining processes. The composition of sterols in free and esterified form were different. Campesterol, stigmasterol and sitosterol were obtained in both free and esterified form, but Δ7 stigmasterol was only found in esterified form. Only small changes in the percentage distribution of the sterols occurred during the processes. Present adress Food Technology Division, ALFA-LAVAL,S-14700 Tumba, Sweden     

Camelina oil and its unusual cholesterol content

The oil in Camelina sativa L. Crantz has a combined linolenic and linoleic acid content that is greater than 50% and a relatively low saturated FA content (∼10%). Although the FA composition has been reported, no information is available on the sterol composition of camelina oil. The derivatized plant sterols were separated and quantified with capillary GC and their identity confirmed with GC-MS. The refined camelina oil sample contained approximately 0.54 wt% unsaponifiables, and over 80% of the unsaponifiables were desmethylsterols. Perhaps the most unusual characteristic of camelina oil is its relatively high content of cholesterol, particularly for a vegetable oil, since it contains several times the cholesterol found in other “high-cholesterol” vegetable oils. Camelina oil also contains relatively large amounts of another unusual sterol, brassicasterol. The major sterols identified in the camelina oil included cholesterol (188 ppm), brassicasterol (133 ppm), campesterol (893 ppm), stigmasterol (103 ppm), sitosterol (1,884 ppm), and Δ⁵-avenasterol (393 ppm).     

Composition of seeds of cruciferous oil crops

Several species of the Cruciferae family are presently used as oilseed crops, viz.,Brassica campestris (turnip rape and sarson),B. juncea (brown or yellow mustard),B. napus (rape),Crambe abyssinica (crambe), andSinapis alba (white or yellow mustard). Seed oils of these species are characterized by variable but generally large amounts of erucic acid (22:1) in the triacylglycerols, which make up 95–98% of the total lipids of high quality, viable seeds. In addition to erucic acid, the major fatty acids are oleic (typically 10–25%), linoleic (10–20%), linolenic (7–11%) and eicosenoic (5–10%). However cultivars of rapeseed lacking erucic acid and having about 55–60% oleic, 20–25% linoleic and ca. 10% linolenic acid have been developed. The eicosenoic and erucic acids are located exclusively at the 1 and 3 positions of the triacylglycerol. As a consequence, major triacylglycerol types have carbon numbers 54, 56, 58, 60 and 62. The phospholipids of rapeseed are essentially devoid of erucic acid and have palmitic, oleic and linoleic acids as major fatty acids. Sterols generally amount to about 0.5% of the oil with β-sitosterol, campesterol and brassicasterol as major constituents (about 55%, 25% and 15%, respectively, of the total sterols). A few per cent of the total sterol fractions is cholesterol. The tocopherol content of rapeseed oil is about 800 ppm with α- and γ-tocopherol as major components. Cruciferous seeds contain a fairly large number of storage proteins. Thus approximately 50 components have been detected in alkaline extracts ofBrassica napus, a major portion of which are in the molecular weight range 120–150,000. The protein spectrum ofB. napus (rape) is more complex than that ofB. campestris (turnip rape) since the former species is an allotetraploid withB. oleracea (kale, cabbage, etc.) andB. campestris as parents. Approximately 5% of the fat free seed meal is composed of glucosinolates, which are split upon enzymatic hydrolysis to antinutritional factors: isothiocyanates, oxazolidinethiones and nitriles. The different crucifers discussed have both qualitative and quantitative differences with respect to glucosinolate content. One of nine papers presented at the Symposium, “Cruciferous Oilseeds,” ISF-AOCS World Congress, Chicago, September 1970.     

Fatty acids and sterols in oils from canola screenings

One sample of canola seed (variety Tower) and five samples of screenings were commercially processed to yield first an “expeller oil” and subsequently an “extractor oil” by the hexane extraction of the residue. The screening samples contained 25–50% intact or broken canola seed. The balance included 21–31% weed seeds (especially lambsquarter and stinkweed), hulls, fragments of the embryo, and chaff. All the oil samples were analyzed for sterol and fatty acid composition. The extractor screening samples had slightly higher sterol contents than the corresponding expeller samples, while the Tower samples gave the lowest values. The averages (in mg/g oil or extract) for the extractor screening samples were: brassicasterol, 1.0; campesterol, 4.1; and β-sitosterol, 7.3. For expeller screening samples the average were: 0.9, 3.6 and 6.2 and for the Tower oils they were, respectively, 0.9, 3.8, 5.3 and 0.9, 3.5, 4.7. The fatty acid compositions of the screening samples for both extractor and expeller oils were similar to that of the Tower oil except for the higher proportions of docosenoic acid (22:1) and eicosenoic acid (20:1) and the more obvious presence of three C₁₈ conjugated dienes totalling up to 0.6% of one screening oil sample. The docosenoic acid level (mainly erucic acid) ranged from 3.0 to 7.0% for the extractor oils and from 2.5 to 8.0% for the expeller samples, compared to 0.1% for the two Tower oils. The oil contents of the screenings ranged from 20 to 30%, and the fatty acids and sterols appear to be nutritionally useful and innocuous in all respects. Presented in part at the ISF/AOCS World Congress, New York, April–May 1980.     

Free and esterified sterols of cotton buds and anthers

Capillary gas liquid chromatography analyses were conducted on free and esterified sterol fractions of cotton (Gossypium hirsutum cv. Stoneville 213) floral buds and anthers. The free sterols of both cotton buds and anthers consist mainly of the common plant sterols sitosterol, stigmasterol and 24ζ-methylcholest-5-en-3β-ol. The composition of esterified sterols of cotton buds and anthers were similar, and consisted of pollinastanol, 31-norcycloartanol, cycloartenol, 31-norcycloartenol, 24-dehydropolinastanol and sitosterol. Desmosterol was also present in both the free and esterified sterols of anthers. The identities of the sterols were confirmed by gas chromatography-mass spectrometry analyses. Esterified sterols accounted for 46.7 and 88.7% of total sterols of cotton bud and anthers, respectively. The ratio of esterified sterol to free sterol per gram of tissue is about 8∶1 in anthers. The Δ⁵-sterols of the esterified sterols of cotton buds and anthers account for only 17 and 9.2% of the total sterols, respectively.     

The lipids of slugs and snails: Evolution,diet and biosynthesis

There is a considerable gap in current knowledge of the lipid composition of snails and slugs, both of which belong to the phylum Mollusca. We have therefore analyzed the sterol and fatty acid compositions of three species of slugs and three species of snails. The sterols of slugs included eight different sterols: cholesterol contributed 76–85% of the total sterols, brassicasterol accounted for 4–13%; other sterols we identified were lathosterol, 24-methylene cholesterol, campesterol, stigmasterol, sitosterol and sitostanol. In contrast, snails contained two additional sterols, desmosterol and cholestanol. Of the polyunsaturated fatty acids in slugs, linoleic (18∶2n−6) and arachidonic acids (20∶4n−6) were the major n−6 fatty acids, while linolenic (18∶3n−3) and eicosapentaenoic acids (20∶5n−3) were the predominant n−3 fatty acids. Docosahexaenoic acid (22∶6n−3), the end product in the n−3 fatty acid synthetic pathway and an important membrane fatty acid of mammals, fish and birds, was absent in both slugs and snails. However, the analogous product of n−6 fatty acid synthesis, 22∶5n−6, was found in both snails and slugs. This raises speculation about preference for n−6 fatty acid synthesis in these species. Our data show the unique sterol and fatty acid compositions of slugs and snails, as well as similarities and differences in sterol composition between the two. The results between the two land mollusks are contrasted with those of marine mollusks, such as oysters, clams and scallops.     

Fatty acid composition of individual plasma steryl esters in phytosterolemia and xanthomatosis

The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins. We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis. For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids. The saturated and unsaturated sterols esterified to saturated, monoenoic, dienoic and tetraenoic fatty acids were identified by GLC analysis of the sterol moieties of the corresponding AgNO₃-TLC fractions of the steryl esters. The GLC results were confirmed by reversed phase high performance liquid chromatography combined with mass spectrometry via direct liquid inlet interface. It was found that, in general, each fatty acid was esterified to the same complement of sterols, and that the esterified sterols possessed a composition comparable to that of the free plasma sterols, which was comprised of about 75% cholesterol, 6% campesterol, 4% 22,23-dihydrobrassicasterol and 15% β-sitosterol. The fatty acid composition of the steryl esters differed from that of the 2-position of the plasma phosphatidylcholines, which contained significantly less palmitic and oleic and more linoleic acid. On the basis of these results and a review of the literature it is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin-cholesterol acyltransferase and synthesis in tissues via the acylCoA-cholesterol acyltransferase.     

A method for the separation of seed oil steryl esters and free sterols: Application to peanut and corn oils

A method for separating and quantitating seed oil steryl esters and free sterols was developed using a combination of preparative column, thin layer (TLC), and gas liquid chromatography (GLC). Cholesteryl heneicosanoate and cholesterol served as internal standards. The method was applied to corn-oil samples (Mazola, Kroger) obtained from the local market and peanut-oil samples prepared in the laboratory from commercial varieties of peanuts (Florunner, Starr). Concentration (mg/100 g oil; mean ± SD) of steryl esters and free sterols in the 4 oils were: Mazola, 1420±40 and 370±8; Kroger, 950±40 and 320±4; Florunner, 74±0.5 and 150±3; and Starr, 51±0.5 and 130±2. Sitosterol was the major sterol in both the free sterol and steryl ester fractions of all oils and together with campesterol, stigmasterol and Δ⁵-avenasterol made up 90–95% of all sterols. Steryl esters of peanut oil contained higher proportions of linoleic acid and long-chain acids (C₂₀–C₂₄) than did whole oil. Corn-oil steryl esters also contained a higher proportion of linoleic acid than did whole oil. Squalene was the major hydrocarbon of all oils with the remaining hydrocarbon fraction consisting of a mixture of compounds. Presented at the AOCS meeting, Toronto, May 1982.     

Quantitative analysis of fatty acids and sterols in Malagasy rice bran oils

The fatty acid and sterol compositions of six Malagasy rice bran oils were evaluated. Investigation by gas liquid chromatography (GLC) using Carbowax 20 M revealed 10 fatty acids, mainly palmitic (16–20%) oleic (41–44%) and linolenic (31–37%) acids. An OV 17 column was used to separate eight sterols, mainly Β-sitosterol (53–59%), campesterol (16–26%) and stigmasterol (10–13%). No significant variation for the fatty acid and sterol contents was observed among the rice varieties studied.     

Triterpene alcohols and sterols of vegetable oils

Triterpene alcohols and sterols were separated by thin-layer chromatography and gas-liquid chromatography from the unsaponifiable fractions of the following 18 vegetable oils: linseed, peanut, olive, rice bran, palm kernel, corn, sesame, oiticica, palm, coconut, rapeseed, grape seed, sunflower, poppy seed, castor, tea seed, cocoa butter and soybean. Two triterpene alcohols, cycloartenol and 24-methylene cycloartanol, were found in all of the oils except soybean oil, which contained only cycloartenol. Triterpene alcohols such as α- and β-amyrin, euphorbol, butyrospermol and cyclolaudenol also were encountered occasionally. Three sterols, β-sitosterol, stigmasterol and campesterol were present in all of the oils. In addition a fourth sterol, not yet idenfified, was found in oils of palm, palm kernel and sunflower in varying amounts. This unknown sterol and brassicasterol were found in rapeseed oil in addition to the three sterols that were common to all of the oils studied. Experiment Station for Fats and Oils, National Center for Lipochemistry of National Research Council, Milan, Italy.     

The effect of dietary erucic acid on cardiac triglycerides and free fatty acid levels in rats

Male Sprague-Dawley rats, 3 weeks of age, were fed semisynthetic diets containing test oils at 20% by weight for 3 days, 1 week, and 16 weeks. The test oils contained up to 22.3% erucic acid. Growth retardation was evident in rats fed rapeseed oil high in erucic acid, and soybean oil and Tower rapeseed oil diets containing about 5% erucic acid. Cardiac triglyceride accumulation was found in rats fed diets containing about 5% erucic acid but not in rats fed Tower rapeseed oil which contains 0.2% of this acid. The cardiac free fatty acid levels were low, 50–100 μg/g of wet heart tissue, and were not affected by feeding diets containing about 5% erucic acid. Feeding a diet containing a high erucic acid rapeseed oil did result in higher free fatty acid levels but only at 3 days and 1 week; the level at 16 weeks was similar to the other oils. The fatty acid analysis of cardiac triglycerides and free fatty acids showed high percentages of erucic acid at 3 days and 1 week; at 16 weeks these levels had declined significantly. The results indicate that the accumulated erucic and eicosenoic acids, at 3 days and 1 week, accounted for the increase in cardiac free fatty acids when rats were fed the high erucic acid rapeseed oil. There appears to be no evidence that the early cardiac triglyceride or free fatty acid accumulation is related to the formation of the long term myocardial lesions. Contribution No. 739 Animal Research Institute.     

Changes in fatty acid composition of cardiac mitochondrial phospholipids in rats fed rapeseed oil

Male Wistar rats were fed rapeseed oil containing high or low levels or erucic acid for 20 weeks, and changes in the fatty acid composition of cardiac mitochondrial phospholipids were studied. Treatment with rapeseed oil containing 46.2% erucic acid showed incorporation of 22∶1 (5.6%) into isolated cardiolipin from heart mitochondria. After high or low (3.7%) erucic rapeseed oil feeding, linoleic acid was slightly incorporated into cardiolipin. Moreover, both of these rapeseed oils induced a significant increase of linoleate-arachidonate ratio in phosphatidylethanolamine and phosphatidylcholine. This ratio was also significantly increased in fatty acids esterified to the β-position of these phospholipids. On the basis of such results, we have to consider the role of linolenic acid which is present at a high level in the different rapeseed oils used, as a possible inhibitor of heart microsomal enzymes involved in linoleate arachidonate conversion. Such alterations might account for mitochondrial fragility and myocardial lesions obtained in long term rapeseed oil feeding experiments. ERA-CNRS n^o 070497     

The Detection of Adulteration with Desterolized Oils

Edible oils are desterolized in order to render them “undetectable” when admixed to other oils. Such frauds remain, however, detectable by the olefinic degradation products of the sterols: the degradation products approximately have the composition of the sterols they originate from. Presence of campestatriene (degraded brassicasterol) reveals the presence of desterolized rapeseed oil. The ratio of the degradation products of sitosterol and campesterol is a sensitive indicator for desterolized sunflower, soybean, palm, or grapeseed oil in oils of low campesterol content, such as olive and walnut oil. Analyses were performed by on-line coupled LC-GC.     

The sterol composition of freshly harvested compared to stored seeds of rape,sunflower and poppy

The composition of the free sterols and the sterol esters of freshly harvested seeds of rape, sunflower and poppy was compared to that of stored seeds. The sterol composition of rapeseed was not changed during storage, whereas in sunflower seed the free sterols had less of Δ5-avenasterol and Δ7-stigmastenol in ten-month-old seeds compared to fresh seeds. The greatest relative changes were observed for esterified sterols in poppy seed, with a drop in the percentage of Δ5-avenasterol from 25.3% in freshly harvested to 16.9% in seeds stored for 10 months.