Phytosterol accumulation in canola, sunflower, and soybean oils: Effects of genetics, planting location, and temperature

To assess the potential of traditional selection breeding to develop varieties with increased phytosterol content, we determined concentrations of those sterols in canola, sunflower, and soybean seed oils produced from breeding lines of diverse genetic backgrounds. Seed oils were extracted and saponified, and the nonsaponifiable fractions were subjected to silylation. The major phytosterols brassicasterol, campesterol, stigmasterol and β-sitosterol, were quantified by capillary gas chromatography with flame-ionization detection. Canola contained approximately twice the amount of total phytosterols (4590–8070 μg g⁻¹) as sunflower (2100–4540 μg g⁻¹) or soybean (2340–4660 μg g⁻¹) oils. Phytosterol composition varied among crops as expected, as well as within a crop. Both genetic background and planting location significantly affected total phytosterol concentrations. Soybean plants were maintained from flower initiation to seed maturity under three temperature regimes in growth chambers to determine the effect of temperature during this period on seed oil phytosterol levels. A 2.5-fold variability in total phytosterol content was measured in these oils (3210–7920 μg g⁻¹). Total phytosterol levels increased with higher temperatures. Composition also changed, with greater percent campesterol and lower percent stigmasterol and β-sitosterol at higher temperatures. In these soybean oils, total phytosterol accumulation was correlated inversely with total tocopherol levels. Owing to the relatively limited variability in phytosterol levels in seed oils produced under field conditions, it is unlikely that a traditional breeding approach would lead to a dramatic increase in phytosterol content or modified phytosterol composition.     

Temperature effects on fatty acid composition during development of low-linolenic oilseed rape (Brassica napus L.)

The influence of temperature during seed development on the fatty acid composition of oilseed rape (Brassica napus L.) was studied in one low-linolenic and one conventional canola cultivar. The cultivar Regent produces seed oil with ∼20% linoleic acid (C18:2) and ∼8% linolenic acid (C18:3), whereas Stellar is relatively high in C18:2 (∼25%) and low in C18:3 (∼2.5%). Both cultivars were grown in the field, and the fatty acid compositions of the seed oils were monitored throughout the period of seed development. In the field, the content of saturated (C16:0+C18:0) and monounsaturated (C18:1) fatty acids in the seed oil increased when seed developed under high temperatures. C18:3 levels were higher in seed harvested at sites with lower average daily temperatures. The low C18:3 trait of the cultivar Stellar was relatively stable over environments. Both temperature and duration of exposure to the temperature during seed development affected the fatty acid composition of the seed in a controlled environment study. Plants subjected to a high-temperature treatment (30/25°C day/night) for 40 d produced seed with the lowest C18:3 content and the highest levels of C16:0+C18:0 and C18:1. This was observed in both cultivars.     

A multivariate study of the correlation between tocopherol content and fatty acid composition in vegetable oils

The main biochemical function of the tocopherols is believed to be the protection of polyunsaturated fatty acids (PUFA) against peroxidation. A critical question that must be asked in reference to this is whether there is a biochemical link between the tocopherol levels and the degree of unsaturation in vegetable oils, the main source of dietary PUFA and vitamin E. We used a mathematical approach in an effort to highlight some facts that might help address this question. Literature data on the relative composition of fatty acids (16:0, 16:1, 18:0, 18:1, 18:2, and 18:3) and the contents of tocopherols (α-, β-, δ-, and γ-tocopherol) in 101 oil samples, including 14 different botanical species, were analyzed by principal-component analysis and linear regression. There was a negative correlation between α- and γ-tocopherols (r=0.633, P<0.05). Results also showed a positive correlation between linoleic acid (18:2) and α-tocopherol (r=0.549, P<0.05) and suggested a positive correlation between linolenic acid (18:3) and γ-tocopherol.     

Fatty acid composition of oil from exotic corn breeding materials

The fatty acid composition of corn oil can be altered to meet consumer demand for “healthful” fats. The first step in altering the oils is to survey existing corn breeding materials for fatty acid composition. The Latin American Maize Project (LAMP), an international program designed to evaluate the agronomic characteristics of maize accessions in Latin American and U.S. germplasm banks for future use, provides useful starting materials. LAMP was based on the cooperative efforts of 12 countries. In a two-stage evaluation, the project identified the highest-yielding open-pollinated top 20% of populations, then approximately the top 5% of those 20%. Twenty of the populations from four countries with temperate climates were randomly selected for fatty acid analysis. The populations were from United States, Chile, Argentina, and Uruguay. Fifty S₁ lines from each population were randomly chosen for analysis for a total of 1,000 genotypes sampled. Statistical differences in fatty acid composition were computed among the 20 populations and among the four countries. The findings showed a wide range of fatty acid profiles present in unadapted, elite corn breeding materials with ranges for each fatty acid as follows: palmitic acid, 6.3–18.2%; stearic acid, 0.9–4.5%; oleic acid, 18.5–46.1%; linoleic acid, 36.6–66.8%; linolenic acid, 0.0–2.0%; and arachidic acid, 0.0–1.4%. Several populations were significantly different from the others. Some lines had unusual fatty acid compositions, including one with 8.3% total saturates and another with 20.2% total saturates. This study shows that existing corn breeding materials could be used to produce high- and low-saturate oils, but other methods would probably be required to produce a high-oleic corn oil.     

Predicting temperature-dependence viscosity of vegetable oils from fatty acid composition

The viscosities of 12 vegetable oils were experimentally determined as a function of temperature (5 to 95°C) by means of a temperature-controlled rheometer. Viscosities of the oil samples decreased exponentially with temperature. Of the three models [modified Williams-Landel-Ferry (WLF), power law and Arrhenius] that were used to describe the effects of temperature on viscosity, the modified WLF model gave the best fit. The amounts of monounsaturated FA or polyunsaturated fatty acids (PUFA) highly correlated (R ²>0.82) with the viscosities of the oil samples whereas and the amounts of saturated or unsaturated FA. An exponential equation was therefore used to relate the viscosity of these vegetable oil samples to the amounts of monounsaturated FA or PUFA. The models developed are valuable for designing or evaluating systems and equipment that are involved in the storage, handling, and processing of vegetable oils.     

Definite influence of location and climatic conditions on the fatty acid composition of sunflower seed oil

Percentages of linoleic, oleic and stearic acids present significant differences between growing areas, whereas palmitic acid content remains practically constant, or at least presents no significant relation to the growing area. Nevertheless, palmitic acid appears to follow a pattern that relates its content to the total content of the other three major fatty acids. Seeds grown in the northern part of Spain presented a higher linoleic content than seeds grown in the South, which is in agreement with the general theory found in prior studies. Although there is an inverse correlation between oleic and linoleic content, we have found that the total content of both is neither constant nor independent of temperature, and increases when temperature and oleic acid increase. However, stearic content increases when the combination of linoleic and oleic acid decreases, suggesting a total constant value for the combination of these three acids. The average temperature of the are during development of the seed and the local climatic conditions have the greatest influence over fatty acid composition, while the seed variety presents limited influence.     

Fatty acid composition of oil from adapted,elite corn breeding materials

The fatty acid composition of corn oil can be altered to meet consumer demands for “healthful” fats (i.e., lower saturates and higher monounsaturates). To this end, a survey of 418 corn hybrids and 98 corn inbreds grown in Iowa was done to determine the fatty acid composition of readily-available, adapted, elite corn breeding materials. These materials are those used in commercial hybrid production. Eighty-seven hybrids grown in France (18 of which also were grown in lowa) were analyzed to determine environmental influence on fatty acid content. The parents of the hybrids and the inbreds were classified in one of four heterotic groups: Lancaster, Stiff Stalk, non-Lancaster/non-Stiff Stalk, and Other.t-Tests and correlation analyses were performed with statistical significance accepted at a level ofP≤0.05. The findings showed a wide range of fatty acid profiles present in adapted, elite corn breeding materials with ranges for each fatty acid as follows: palmitic acid, 6.7–16.5%; palmitoleic acid, 0.0–1.2%; stearic acid, 0.7–6.6%; oleic acid, 16.2–43.8%; linoleic acid, 39.5–69.5%; linolenic acid, 0.0–3.1%; and arachidic acid, 0.0–1.0%. Small amounts of myristic acid, margaric acid, and gadoleic acid also were found. Three lines had total saturates of 9.1% or less. Thirty-six of thet-tests involving hybrids showed significant differences among heterotic groups. There were small but significant correlations among protein, starch and oil content and the amounts of several fatty acids. Results from the corn grown in France vs. lowa demonstrated a large environmental effect that overwhelmed the genetic differences among lines. This study shows that for some attributes, a breeding program involving adapted corn breeding materials might produce the desired oil. Other types of oil (such as high-oleic) would have to be produced in a different manner, for example, by a breeding program with exotic breeding materials.     

Triacylglycerol composition and structure in genetically modified sunflower and soybean oils

Changes in composition were examined in oils extracted from genetically modified sunflower and soybean seeds. Improvements were made to the analytical methods to accomplish these analyses successfully. Triacylglycerols (TAG) were separated on two 300 mm × 3.9 mm 4μ Novapak C18 high-performance liquid chromatography (HPLC) columns and detected with a Varex MKIII evaporative light-scattering detector. Peaks were identified by coelution with known standards or by determining fatty acid composition of eluted TAG by capillary gas chromatography (GC). Stereospecific analysis (fatty acid position) was accomplished by partially hydrolyzing TAG with ethyl magnesium bromide and immediately derivatizing the resulting diacylglycerols (DAG) with (S)-(+)-1-(1-naphthyl)ethyl isocyanate. The derivatized sn-1,2-DAG were completely resolved from the sn-2,3-DAG on two 25 mm × 4.6 mm 3 μ silica HPLC columns. The columns were chilled to −20°C to obtain baseline resolution of collected peaks. The distribution of fatty acids on each position of the glycerol backbone was derived from the fatty acid compositions of the two DAG groups and the unhydrolyzed oil. Results for the sn-2 position were verified by hydrolyzing oils with porcine pancreatic lipase, isolating the resulting sn-2 monoacylglycerols by TLC, and determining the fatty acid compositions by GC. Results demonstrated that alterations in the total fatty acid composition of these seed oils are determined by the concentration of TAG species that contain at least one of the modified acyl groups. As expected, no differences were found in TAG with fatty acid quantities unaffected by the specific mutation. In lieu of direct metabolic or enzymatic assay evidence, the authors’ positional data are nevertheless consistent with TAG biosynthesis in these lines being driven by the mass action of available acyl groups and not by altered specificity of the acyltransferases, the compounds responsible for incorporating fatty acids into TAG.     

Density estimation for fatty acids and vegetable oils based on their fatty acid composition

The liquid density of fatty acids can be accurately estimated by the modified Rackett equation over a wide range of temperatures. The modified Rackett equation requires the critical properties and an empirical parameter,Z _RA , for each acid as the basis for computing density as a function of temperature. The liquid density of vegetable oils can be estimated by using mixture properties corresponding to the fatty acid composition and a correction for the triglyceride form. The density prediction is explicitly temperature-dependent.     

Impact of development periods on chemical properties and bioactive components of safflower (Carthamus tinctorius L.) varieties

This study aimed to determine the chemical properties (fatty acid composition, oil content, sterol and tocopherol compositions) of the oils extracted from the seeds of safflower (Dinçer, Remzibey, Balci, Linas, Yenice, Olas) varieties harvested in different periods from flowering to ripening period. In parallel with the increase of harvest time, the humidity rate decreased, while the oil ratios increased. It was determined that palmitic (16:0) and stearic (18:0) acids, which are significant saturated fatty acids, and oleic (18:1) and linoleic (18:2) acids, which are unsaturated fatty acids, are quite high in the oils of all safflower varieties. These fatty acids showed significant changes from the first harvest to the last harvest. The total saturated fatty acid ratios decreased, while the amount of unsaturated fatty acids increased as the maturation progressed. The first and latest harvest samples of Dinçer, Remzibey, Balcı, Linas, Yenice, Olas cultivars were selected and their sterol and tocopherol compositions were examined. The highest level of sterol in all cultivars was β-sitosterol and the amount of sterols decreased towards full maturity. It was determined that α-tocopherol was the dominant tocopherol found in the safflower oils and the amount of tocopherol increased towards full maturity.     

Study on the composition of rice bran oil and its higher free fatty acids value

The compositions of rice bran oils (RBO) and three commercial vegetable oils were investigated. For refined groundnut oil, refined sunflower oil, and refined safflower oil, color values were 1.5–2.0 Lovibond units, unsaponifiable matter contents were 0.15–1.40%, tocopherol contents were 30–60 mg%, and FFA levels were 0.05–0.10%, whereas refined RBO samples showed higher values of 7.6–15.5 Lovibond units for color, 2.5–3.2% for unsaponifiable matter, 48–70 mg% for tocopherols content, and 0.14–0.55% for FFA levels. Of the four oils, only RBO contained oryzanol, ranging from 0.14 to 1.39%. Highoryzanol RBO also showed higher FFA values compared with the other vegetable oils studied. The analyses of FA and glyceride compositions showed higher palmitic, oleic, and linoleic acid contents than reported values in some cases and higher partial glycerides content in RBO than the commonly used vegetable oils. Consequently, the TG level was 79.9–92% in RBO whereas it was >95% in the other oils studied. Thus, refined RBO showed higher FFA values, variable oryzanol contents, and higher partial acylglycerol contents than commercial vegetable oils having lower FFA values and higher TG levels. The higher oryzanol levels in RBO may contribute to the higher FFA values in this oil.     

Environmental effects on fatty acid levels in soybean seed oil

FA composition determines the quality of vegetable oil. Soybean breeders have generated and used mutations in FA genes to develop altered FA profiles in the seed. However, the expression of the alleles and the relative activity of the gene products are often dependent on the environment, and these facts have hampered the breeding efforts. To investigate the environmental effect on FA composition of soybean seed oil in specific mutant material developed at the University of Guelph, a recombinant inbred line (RIL) population was developed from a cross between a low palmitate (16∶0) line and a high-stearate (18∶0) parent. The RIL population was field-tested across three environments over 2 yr. A combined ANOVA for FA composition was conducted to determine the year and location effects on the expression of FA alleles in this material. The results indicated that linolenic (18∶3) level was most vulnerable to the environmental changes. Year effects accounted for a greater amount of variance than location effects for 16∶0, 18∶0, and 18∶1, whereas location effects were more important than year effects for the relative amounts of 18∶2 and 18∶3. Genotype × environment (year, location) interaction effects were significant for the relative amounts of all five FA according to the combined ANOVA. Our results indicated that the extreme minimum daily temperatures during September seed fill period, rather than the means or the maximum temperature, may be responsible for the ratio of saturated vs. unsaturated FA in soybean oil.     

Determination of trans fatty acids and fatty acid profiles in margarines marketed in spain

Two gas chromatography (GC) procedures were compared for routine analysis of trans fatty acids (TFA) of vegetable margarines, one direct with a 100-m high-polarity column and the other using argentation thin-layer chromatography and GC. There was no difference (P>0.05) in the total trans 18∶1 percentage of margarines with a medium level of TFA (∼18%) made using either of the procedures. Both methods offer good repeatability for determination of total trans 18∶1 percentage. The recoveries of total trans isomers of 18∶1 were not influenced (P>0.1) by the method used. Fatty acid composition of 12 Spanish margarines was determined by the direct GC method. The total contents of trans isomers of oleic, linoleic, and linolenic acids ranged from 0.15 to 20.21, from 0.24 to 0.99, and from 0 to 0.47%, respectively, and the mean values were 8.18, 0.49, and 0.21%. The mean values for the ratios [cis-polyunsaturated/(saturated +TFA)] and [(cis-polyunsaturated + cis-monounsaturated)/(saturated +TFA)] were 1.25±0.39 and 1.92±0.43, respectively. Taking into account the annual per capita consumption of vegetable margarine, the mean fat content of the margarines (63.5%), and the mean total TFA content (8.87%), the daily per capita consumption of TFA from vegetable margarines by Spaniards was estimated at about 0.2 g/person/d.     

Determination of the fatty acid composition of canola,flax, and solin by near-infrared spectroscopy

The ability to rapidly measure key FA in oilseed crops would assist in the administration of identity-preserved systems in the grain-handling system or in selection systems in plant-breeding programs. This study shows near-infrared reflectance (NIR) spectroscopy to be a reliable method of determining FA composition in canola, flax, and solin (low-linolenic flax), for oleic acid, linoleic acid, linolenic acid, and iodine value, and to a limited extent for saturated fat. Samples from cultivar trials, harvest surveys, and export shipments were scanned on a NIRSystems 6500 spectrometer (Silver Spring, MD), and calibrations were developed and optimized using modified partial least squares. SE of prediction results for prediction sets of canola, flax, and solin, were, respectively: oleic acid (0.77, 1.03, 0.62%); linoleic acid (0.71, 1.20, 0.37%); linolenic acid (0.42, 0.62, 0.08%); saturated FA (0.23, 0.39, 0.31%); and iodine value (0.63, 0.95, 0.43 units). This paper was previously presented at the 93rd AOCS Annual Meeting & Expo in Montréal, Québec, Canada, May 5–8, 2002, as part of the symposium entitled Use of Spectroscopic Methods to Determine the Fatty Acid Composition of Oils and Oilseeds.     

Fatty acid composition and contents of trans monounsaturated fatty acids in frying fats, and in margarines and shortenings marketed in Denmark

This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the fast-food restaurants Burger King and McDonald’s. Trans C_18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines of 0.4±0.8%. Shortenings had an even higher content of trans C_18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20% total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C_18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C_18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C_18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day.     

Fatty acid composition and contents of trans monounsaturated fatty acids in frying fats, and in margarines and shortenings marketed in Denmark

This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the fast-food restaurants Burger King and McDonald’s. Trans C_18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines of 0.4±0.8%. Shortenings had an even higher content of trans C_18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20% total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C_18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C_18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C_18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day.     

Phospholipid fatty acid composition and stereospecific distribution of soybeans with a wide range of fatty acid composition

Phospholipid (PL) fatty acid composition and stereospecific distribution of 25 genetically modified soybean lines with a wide range of compositions were determined by gas chromatography and phospholipase A₂ hydrolysis. Pl contained an average of 55.3% phosphatidylcholine, 26.3% phosphatidylethanolamine, and 18.4% phosphatidylinositol. PL class proportions were affected by changes in overall fatty acid composition. PL fatty acid composition changed with oil fatty acid modification, especially for palmitate, stearate, and linolenate. Stereospecific analysis showed that saturated fatty acids were primarily located at the sn-1 position of all PL, and changes of the saturates in PL were largely reflected on this position. Oleate was distributed relatively equally between the sn-1 and sn-2 positions. Linoleate was much more concentrated on sn-2 than on sn-1 position for all PL. Linolenate was distributed relatively equally at low concentration but preferred sn-2 position at high concentration.     

Microwave roasting effects on the physico-chemical composition and oxidative stability of sunflower seed oil

The purpose of the present study was to explore the influences of microwave heating on the composition of sunflower seeds and to extend our knowledge concerning the changes in oxidative stability, distribution of FA, and contents of tocopherols of sunflower seed oil. Microwaved sunflower seeds (Helianthus annuus L.) of two varieties, KL-39 and FH-330, were extracted using n-hexane. Roasting decreased the oil content of the seeds significantly (P<0.05). The oilseed residue analysis revealed no changes in the contents of fiber, ash, and protein that were attributable to the roasting. Analysis of the extracted oils demonstrated a significant increase in FFA, p-anisidine, saponification, conjugated diene, conjugated triene, density, and color values for roasting periods of 10 and 15 min. The iodine values of the oils were remarkably decreased. A significant (P<0.05) decrease in the amounts of tocopherol constituents of the microwaved sunflower oils also was found. However, after 15 min of roasting, the amount of α-tocopherol homologs was still over 76 and 81% of the original levels for the KL-39 and FH-330 varieties, respectively. In the same time period, the level of σ-tocopherol fell to zero. Regarding the FA composition of the extracted oils, microwave heating increased oleic acid 16–42% and decreased linoleic acid 17–19%, but palmitic and stearic acid contents were not affected significantly (P<0.05).     

Fatty acid and 3‐hydroxy fatty acid composition of two Hypericum species from Turkey

The fatty acid compositions of flowering tops of Hypericum perforatum L. and Hypericum retusum Aucher (Guttiferae) were analyzed by gas chromatography and gas chromatography‐mass spectrometry. The major components were C16:0 (24.87%), C18:3 n‐3 (21.94%), 3‐OH‐C18:0 (18.46%) and 3‐OH‐C14:0 (14.22%) for H. perforatumL. and 3‐OH‐C14:0 (28.29%), C18:0 (16.47%) and C16:0 (14.17%) for H. retusum Aucher. Besides widespread plant fatty acids, 3‐hydroxy fatty acids, namely 3‐hydroxytetradecanoic acid (3‐OH‐C14:0) and 3‐hydroxyoctadecanoic acid (3‐OH‐C18:0) were also obtained.