NIR reflectance spectroscopic analysis of the FA composition in sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) seeds

The feasibility of using NIR reflectance spectroscopy to estimate the FA composition of sesame seed (Sesamum indicum L.) samples from the National Institute of Crop Science of Japan and from Myanmar was examined. Multiple linear-regression analyses of NIR sepctral data and chemical data for whole seeds were carried out to develop calibration equations for predicting the proportion of each of the four major FA in sesame seeds from the total FA composition. The SE of prediction (SEP) was 0.616% for palmitic acid, 0.348% for stearic acid, 1.051% for oleic acid, and 0.826% for linoleic acid. This NIR method provides a simple, rapid, and nondestructive means of estimating the FA composition of sesame seeds for breeding selection, regardless of the color of the sesame seed coats. However, the proportions of palmitic and stearic acids could not be reliably measured because their SEP were almost as great as the SD of their concentrations in the set of prediction samples. The relationship between NIR spectral patterns and the FA composition of sesame seeds also was examined. The correlation coefficient calculated for the standardized second-derivative NIR spectral readings at 1708 nm and the percentages of linoleic acid was −0.830. A rough estimate of the proportion of linoleic acid in the total FA composition of sesame seeds could be obtained even with single sesame seeds, except for those with a black coat, based on NIR spectral pattern analysis using the wavelength assignments of linoleic acid.     

Genetic diversity for lipid content and fatty acid profile in rice bran

Rice (Oryza sativa L.) bran contains valuable nutritional constituents, which include lipids with health benefits. A germplasm collection consisting of 204 genetically diverse rice accessions was grown under field conditions and evaluated for total oil content and fatty acid (FA) composition. Genotype effects were highly statistically significant for lipid content and FA profile (P<0.001). Environment (year) significantly affected oil content (P<0.05), as well as stearic, oleic, linoleic, and linolenic acids (all with P<0.01 or lower), but not palmitic acid. The oil content in rice bran varied relatively strongly, ranging from 17.3 to 27.4% (w/w). The major FA in bran oil were palmitic, oleic, and linoleic acids, which were in the ranges of 13.9–22.1, 35.9–49.2, and 27.3–41.0%, respectively. The ratio of saturated to unsaturated FA (S/U ratio) was highly related to the palmitic acid content (r ²=0.97). Japonica lines were characterized by a low palmitic acid content and S/U ratio, whereas Indica lines showed a high palmitic acid content and a high S/U ratio. The variation found suggests it is possible to select for both oil content and FA profile in rice bran.     

Chemical composition and physicochemical and hydrogenation characteristics of high-palmitic acid solin (low-linolenic acid flaxseed) oil

The physicochemical characteristics and FA compositions were determined for refined-bleached-deodorized (RBD) high-palmitic acid solin (HPS) oil, RBD solin oil, and degummed linseed oil. The predominant FA in HPS oil were palmitic (16.6%), palmitoleic (1.4%), stearic (2.5%), oleic (11.3%), linoleic (63.7%), and linolenic (3.4%). HPS oil was substantially higher in palmitic acid than either solin oil or linseed oil, and similar to solin oil in linolenic acid content. HPS, solin, and linseed oils exhibited similar sterol and tocopherol profiles. The physicochemical characteristics of the three oils (iodine value, saponification value, m.p., density, specific gravity, viscosity, PV, FFA content, color) reflected their FA profiles and degree of refinement. During hydrogenation of HPS oil, the proportion of saturated FA (palmitic and stearic) increased, and that of unsaturated FA (oleic, linoleic, and linolenic) decreased as the iodine value declined. This resulted in an inverse linear relationship between m.p. and iodine value. Hydrogenation also generated trans FA. The proportion of trans FA was inversely related to iodine value in partially hydrogenated samples. Fully hydrogenated HPS oil (i.e., HPS stearine, iodine value <5) was devoid of trans FA.     

Lipid characterization of seed oils from high-palmitic,low-palmitoleic,and very high-stearic acid sunflower lines

Information obtained in recent years regarding the enzymes involved in FA synthesis can now be applied to develop novel sunflower lines by incorporating enzymes with specific characteristics into lines with a defined background. We have generated three highly saturated mutant lines in this way and characterized their FA content. The new high-palmitic, low-palmitoleic lines CAS-18 and CAS-25, the latter on a high-oleic background, have been selected from the high-stearic mutant CAS-3 by introducing a deficient stearic acid desaturase in a high-palmitic background from the previously developed mutant lines CAS-5 and CAS-12, respectively. As such, the desaturation of palmitic acid and the synthesis of palmitoleic acid and its derivatives (asclepic and palmitolinoleic acids) were reduced in these high-palmitic lines, increasing the stearic acid content. Likewise, introducing a FA thioesterase from a high-palmitic line (e.g., CAS-5) into the high-stearic CAS-3 increased the stearic acid content from 27 to 32% in the new high-stearic line CAS-31. As previously described in high-palmitic lines, high growth temperatures did not reduce the linoleic acid content of the oil. Furthermore, the FA composition of TAG, DAG, and phospholipids was modified in these lines. Besides a high degree of saturation, the TAG from these new vegetable oils have a low content of saturated FA in the sn-2 position. The α asymmetric coefficient obtained also indicates that the saturated FA are asymmetrically distributed within the TAG molecules. Indeed, the disaturated TAG content rose from 31.8 to 48.2%. These values of disaturated TAG are the highest to date in a temperate oilseed.     

Effects of stearic acid on plasma lipid and lipoproteins in humans

More than 40 years ago, saturated FA with 12, 14, and 16 carbon atoms (lauric acid, myristic acid, and palmitic acid) were demonstrated to be “hypercholesterolemic saturated FA.” It was further concluded that the serum total cholesterol level would hardly be changed by isocaloric replacement of stearic acid (18∶0) by oleic acid (cis-18∶1n−9) or carbohydrates. These earlier studies did not address the effects of the various FA on the serum lipoprotein profile. Later studies found that the hypercholesterolemic saturated FA increase serum total cholesterol levels by raising concentrations of both the atherogenic LDL and the antiatherogenic HDL. Consequently, the ratio of total to HDL cholesterol will hardly change when carbohydrates replace these saturated FA. Compared with other saturated FA, stearic acid lowers LDL cholesterol. Studies on the effects on HDL cholesterol are less conclusive. In some, the effects on HDL cholesterol were comparable to those of palmitic acid, oleic acid, and linoleic acid, whereas in others a decrease was observed. This may suggest that in this respect the source of stearic acid is of importance, which needs however further study. From all these studies, however, it can be concluded that stearic acid may decrease the ratio of total to HDL cholesterol slightly when compared with palmitic or myristic acid. Without doubt, the effects of stearic acid are more favorable than those of trans monounsaturated FA.     

Relation of days after flowering to chemical composition and physiological maturity of sunflower seed

Hybrid sunflower seed (achene) were collected from plants at 7-day intervals after the initiation of flowering which occurred 58 days after planting. The seed were analyzed for moisture, total oil, free fatty acids, lipid classes, and fatty acid composition. Seed dry weight, oil and triglyceride contents were maximum 35 days after the initiation of flowering (DAF) when the seed moisture content was about 36%. This point was defined as “physiological maturity” for sunflowers. The fatty acid composition of the oil extracted from the seed was determined at each stage of maturity. Total saturated fatty acids were 27% at 7 DAF and then decreased to a constant 9% by 35 DAF. At 7 DAF, linolenic acid content was 10.7% then decreased to less than 0.1% by 28 DAF. Oleic acid was about 12% at 7 DAF, increased to 59.6% at 14 DAF, and then gradually decreased to 31.4% by 56 DAF. On the other hand, linoleic acid was about 48% at 7 DAF, decreased to 23% by 14 DAF, but then gradually increased to 59.2% by 56 DAF. An analysis of variance of linoleic and oleic acid contents from 21 DAF to 70 DAF showed a highly significant change in composition with maturation time. The changes in the composition of these fatty acids from 21 DAF to 70 DAF appeared to be related to the environmental temperature which gradually decreased until 56 DAF. Increase in free fatty acids after physiological maturity indicated that deterioration of seed oil was beginning to occur.     

Characterization of polar and nonpolar seed lipid classes from highly saturated fatty acid sunflower mutants

The seed lipids from five sunflower mutants, two with high palmitic acid contents, one of them in high oleic background, and three with high stearic acid contents, have been characterized. All lipid classes of these mutant seeds have increased saturated fatty acid content although triacylglycerols had the highest levels. The increase in saturated fatty acids was mainly at the expense of oleic acid while linoleic acid levels remained unchanged. No difference between mutants and standard sunflower lines used as controls was found in minor fatty acids: linolenic, arachidic, and behenic. In the high-palmitic mutants palmitoleic acid (16∶1n−7) and some palmitolinoleic acid (16∶2n−7, 16∶2n−4) also appeared. Phosphatidylinositol, the lipid with the highest palmitic acid content in controls, also had the highest content of palmitic or stearic acids, depending on the mutant type, suggesting that saturated fatty acids are needed for its physiological function. Positional analysis showed that mutant oils have very low content of saturated fatty acids in the sn-2 position of triacylglycerols, between the content of olive oil and cocoa butter.     

Variation in composition of sunflower oil from composite samples and single seeds of varieties and inbred lines

The seed oil of eight sunflower varieties grown at 10 locations in 1964 and 14 locations in 1964 showed highly significant differences between varieties and between stations in mean values for percentage of stearic, oleic and linoleic acids but no significant difference for palmitic acid. The same observations held for oleic and linoleic acids in three varieties common to eight stations in the two years. The only significant interaction appearing in these studies was between years and stations. Varieties requiring the same time to mature differed significantly. Oil from composite samples of inbred lines showed large differences in composition, e.g., the ranges in 56 lines grown in one season at one location were: palmitic 4.7–8.2%; stearic 1.7–9.1%; oleic 13.9–40.3%; and linoleic 47.9–76.4%. Single seeds within inbred lines also showed striking variation. The greatest variation occurred in lines inbred for one to three generations and the least in lines inbred for eight to nine generations. Pairs of lines with identical or similar flowering date differed significantly in mean values of all four acids. Variation between seeds within varieties were relatively narrow in Armavirec and Advent, but wide in Peredovik where the range was: palmitic 4.5–9.4%; stearic 2.5–12.4%; oleic 14.8–46.4%; and linoleic 34.3–75.5%. The results show that genetic control of oil quality, independent of flowering or maturity date, exists in sunflowers. The wide range in composition suggests that altering oil quality in the crop by breeding is a practical objective. Contribution No. 73, Research Station, Research Branch, Canada Department of Agriculture, Morden, Manitoba and contribution No. 97, Analytical Chemistry Research Service, Ottawa. Presented at the AOCS Meeting, Chicago, October 1967.     

Oil, Fatty Acid Profile and Karanjin Content in Developing Pongamia pinnata (L.) Pierre Seeds

Oil content, fatty acid composition and karanjin content were studied in developing pongamia seeds, at intervals of 3?weeks from 30?weeks after flowering up to 42?weeks. Three marked stages in seed development were observed at the early green pod stage, the middle half brown stage and the late dark brown stage. Significant variation in seed biomass, pod and seed characteristics were observed. A significant (P?<?0.01) decrease in the moisture content of the seeds was observed during seed development. The oil content gradually increased from 32.06 to 36.53?% as the seed matured. A significant variation in fatty acid composition was detected across all stages of seed development. Palmitic acid (16:0) content marginally decreased from 11.81 to 10.18?%, while stearic acid (18:0) and linolenic acid (18:3) remained constant at all stages of seed maturity. A steady increase in oleic acid (18:1) content from 38.11 to 49.11?% was observed, while the linoleic acid (18:2) content decreased from 30.14 to 18.85?%. The iodine value increased, while the saponification number of oil decreased during seed development. The increase in karanjin content was steady. Seeds harvested after 42?week after flowering yielded the maximum oil with high oleic acid content which could be suitable for biodiesel production.     

Influence of stearic acid on hemostatic risk factors in humans

Stearic acid has been claimed to be prothrombotic. Elevated plasma factor VII coagulant activity (FVIIc) may raise the risk of coronary thrombosis in the event of plaque rupture. Fibrinogen, an acute-phase protein, is necessary for normal blood clotting; however, elevated levels of fibrinogen increase the risk of coronary heart disease (CHD). Here I report the results of three controlled, human dietary intervention studies, which used a randomized crossover design to investigate the hemostatic effects of stearic acid-rich test diets in healthy young men. A diet high in stearic acid (shea butter) resulted in a 13% lower fasting plasma FVIIc than a high palmitic acid diet, and was 18% lower than a diet high in myristic and lauric acids (P=0.001) after 3 wk of intervention. The stearic acid-rich test fat increased plasma fibrinogen concentrations slightly compared with the myristic-lauric acid diet (P<0.01). When investigating the acute effects of fatty meals, those high in stearic acid (synthesized test fat) resulted in a smaller postprandial increase in FVII than those high in trans and oleic FA, indicating a smaller increase in activated FVII after ingesting stearic acid compared with fats high in monounsaturated FA, probably caused by lower postprandial lipemia. Thus, the present investigations did not find dietary stearic acid to be more thrombogenic, in either fasting effects compared with other longchain FA, or in acute effects compared with dietary unsaturated FA, including trans monounsaturated FA. The slightly increased effect on fasting plasma fibrinogen may be biologically insignificant, but it should be investigated further.     

Fatty acid composition of oil from soybean seeds grown at extreme temperatures

Temperature during seed development is known to influence the level of the various fatty acids in soybean [Glycine max (L.) Merr.] oil. In order to determine the range of values that can be obtained for each fatty acid, five lines (A5, C1640, N78-2245, PI 123440 and PI 361088B) known to possess low linolenic acid (18:3) levels, one line (A6) known to possess a high stearic acid (18:0) level, and two cultivars (Century and Maple Arrow) were grown at 40/30, 28/22, and 15/12°C day/night. At 40/30°C, high oleic acid (18:1), low linoleic acid (18:2), and low linolenic acid levels were obtained that were beyond the range of levels reported for the soybean germplasm. The linolenic acid levels for A5, C1640 and N78-2245 grown at 40/30°C were below 2.0%, and are the lowest values reported for soybean oil. A6 displayed a high level of stearic acid at 28/22 and 40/30°C but displayed a relatively low level at 15/12°C. This indicates that temperature may affect the expression of thefas ^a allele, which is responsible for high stearic acid levels in A6. The linolenic acid levels of PI 361088B and C1640, both possessing thefan allele, were the lowest for all lines grown at 15/12°C. Therefore, thefan allele is an appropriate source for the development of low linolenic acid lines adapted to cool areas.     

Non-destructive Determination of High Oleic Acid Content in Single Soybean Seeds by Near Infrared Reflectance Spectroscopy

Soybean [Glycine max (L.) Merr] with increased oleic acid is desirable to improve oxidative stability and functionality of soybean seed oil. Recently, soybean genotypes with high oleic acid (≥70 %) were developed by breeding programs. Efficient and effective identification of high oleic acid soybean genotypes using non-destructive near infrared reflectance (NIR) on whole seeds would greatly enhance progress in breeding programs. The objective of this study was to develop a calibration equation for NIR determination of high oleic acid from single soybean seeds. A total of 600 intact, single F₂ seeds were scanned by NIR. Spectral data were collected between 400 and 2,500 nm at 2 nm intervals. The relationship between NIR spectral patterns of each soybean seed and its oleic acid content was examined. The best predicted equations for oleic acid were selected on the basis of minimizing the standard error of cross-validation and increasing the coefficient of determination. Validation demonstrated that the equations for determining total oleic acid and over 50 % oleic acid content had high predictive ability (r ² = 0.91 and r ² = 0.99, respectively). To validate the newly developed equation, F₂ seeds from a different genetic background were tested. Again, high oleic acid from single soybean seeds was accurately predicted from various genetic backgrounds. Therefore, applying the calibration equations to NIR will be useful to rapidly and efficiently select high oleic acid soybean genotypes in breeding programs.     

Fatty acid composition of oil from soybean leaves grown at extreme temperatures

Leaves from soybean (Glycine max (L.) Merr.) plants were assayed to determine if the relationship between temperature and relative fatty acid composition observed in the seed oil also existed for the triglycerides in the leaf oil. Leaf samples were harvested from eight soybean lines (A5, A6, C1640, Century, Maple Arrow, N78-2245, PI 123440 and PI 361088B) grown at 40/30,28/22 and 15/ 12°C day/night. At 40/30 and 28/22°C, seven fatty acids were observed at a level greater than 1.0%. These included the five major fatty acids found in the seed oil: palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2) and linolenic (18:3) acid; plus two fatty acids that had retention times the same as palmitoleic (16:1) and γ-linolenic (18:3 g) acid. In addition, an eighth fatty acid that had a retention time the same as behenic (22:0) acid was found in the leaves of all lines at 15/12°C. Palmitic, palmitoleic and stearic acid content did not differ significantly over temperatures. The oleic and linoleic acid content were each highest at 15/12°C, while the γ-linolenic and the linolenic acid content were each highest at 40/30°C. The fatty acid composition of the triglyceride portion of the leaf oil did not display the same pattern over temperatures as that observed for seed oil.     

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).     

Lipid synthesis and acyl-CoA synthetase in developing rice seeds

Developing rice seeds rapidly accumulated storage lipids between 5 and 12 d after flowering. The contents of palmitic, oleic, and linoleic acids increased throughout seed development, while the alpha-linolenic acid content remained low. The activity of acyl-CoA synthetase varied coincidentally during the period of lipid accumulation, and rice seeds had a sufficient capacity to supply acyl-CoA substrates for TAG synthesis. Acyl-CoA synthetase showed a broad specificity for native FA of rice seeds except for stearic acid, and pi electrons of a delta9-delta11 double bond in the C16-C18 acyl chains were required for its maximal activity.     

Influence of Temperature on the Fatty Acid Composition of the Oil From Sunflower Genotypes Grown in Tropical Regions

The influence of temperature on the fatty acid composition of the oils from conventional and high oleic sunflower genotypes grown in tropical regions was evaluated under various environmental conditions in Brazil (from 0° S to 23° S). The amounts of the oleic, linoleic, palmitic and stearic fatty acids from the sunflower oil were determined using gas chromatography (GC). The environment exhibited little influence on the amounts of oleic and linoleic fatty acids in high oleic genotypes of sunflower. In conventional genotypes, there was broad variation in the average amounts of these two fatty acids, mainly as a function of the minimum temperature. Depending on the temperature, especially during the maturation of the seeds, the amount of oleic acid in the oil of conventional sunflower genotypes could exceed 70 %. Higher temperatures led to average increases of up to 35 % for this fatty acid. Although the minimum temperature had the strongest effect on the fatty acid composition, locations at the same latitude with different minimum temperatures displayed similar values for both oleic acid and linoleic acid. Furthermore, minimum temperature had little influence on the amounts of palmitic and stearic fatty acids in the oil.     

Inhibition of desaturation of stearic acid in livers of rats fed ethionine

The effect of ethionine on the conversion of stearic acid to oleic acid was studied. Rats were fed essential fatty acid (EFA) deficient diet for three weeks, after which time half the animals were fed 0.25% DL-ethionine for nine additional days. Seventeen hours prior to killing, they were fed a slurry of the diet containing 18-¹⁴C-stearic acid. Liver triglycerides and phospholipids were extracted and separated and their fatty acid composition and the distribution of radioactivity between stearic and oleic acid was determined. In the tissues studied, oleic acid was maintained at control levels in ethionine-fed rats, but eicosatrienoic acid was significantly depressed. Distribution of radioactivity and specific activity of oleic acid in the triglycerides and phospholipids were significantly reduced by the analogue. In vitro studies of desaturation and chain elongation reactions, with liver microsomes, using 18-¹⁴C-stearic and 1-¹⁴C-linoleic acids as substrates, showed that ethionine depressed the synthesis of oleic acid from stearic and γ-linolenic from linoleic acid. Elongation of linoleic adie to a 20∶2 fatty acid was unaffected by ethionine. Therefore, the results showed that ethionine inhibited desaturation of stearic to oleic acid in vivo and in vitro and probably also impaired the desaturation of oleic to octadeca-6, 9-dienoic acid. Maintenance of control levels of oleic acid in the tissues of ethionine-fed, EFA deficient rats suggested the presence of synthetic pathways for oleic acid other than via desaturation of stearic acid. Presented in part at the AOCS Meeting, San Francisco, April 1969.     

Electrochemical reduction of rubber seed oil to stearic acid

The reduction of rubber seed oil to stearic acid was investigated under potentiostatic conditions in a medium of isopropanol and hydrochloric acid at a pH of 2.0–2.2. The efficiency of reduction was studied on various cathode materials. No reduction was observed on low-hydrogen-overvoltage materials such as platinum and nickel. However, rubber seed oil underwent successful reduction to stearic acid at a monel gauze cathode, which showed high hydrogen overvoltage. The yield was in the region of 70% at a current efficiency of 65%. The final crystalline product showed the presence of 81.5% stearic and oleic acids in contrast to the original oil which contained only 39.3% of these two acids, thus showing the almost complete reduction of linolenic and linoleic acids to stearic acid. The cathode material, the porosity of the ceramic diaphragm, the cathode potential and the pH of the medium were found to be the most critical parameters controlling this reduction process. Studies are now in progress to look into the industrial and economic viability of this conversion.