Preparation of stearidonic acid‐enriched triacylglycerols from Echium plantagineum seed oil

HPLC analysis of Echium plantagineum seed oil shows a complex triacylglycerol (TAG) profile. TAG species were separated on an analytical scale by HPLC and their fatty acid (FA) composition is reported. GLC analyses showed that some TAG fractions reached a stearidonic acid (SDA, 18:4n‐3) percentage significantly higher than that in the original oil. TAG separation on a bigger scale was also essayed, by means of a gravimetric normal‐phase chromatographic column, using silver ion‐silica gel as stationary phase. Gradient elution with solvents of increasing polarity was applied, allowing the separation of valuable TAG species containing γ‐linolenic acid (GLA, 18:3n‐6), α‐linolenic acid (ALA, 18:3n‐3) and SDA as the main constituents (more than 85% of the total FA). An enzymatic hydrolysis reaction showed the distribution of FA in the isolated species of TAG. SDA was the major FA in the sn‐2 position (more than 50% of total FA), followed by ALA (19%) and GLA (18.5%).     

Lipid classes,fatty acid composition and triacylglycerol molecular species of kidney beans (Phaseolus vulgaris L.)

Seed oils from five legume cultivars of Phaseolus vulgaris, grown in Japan, were extracted and classified by thin‐layer chromatography (TLC) into seven fractions: hydrocarbons (HC; 0.7–1.4 wt‐%), steryl esters (SE; 1.7–3.3 wt‐%), triacylglycerols (TAG; 33.8–45.9 wt‐%), free fatty acids (FFA; 0.6–1.5 wt‐%), sn‐1,3‐diacylglycerols (1,3‐DAG; 0.3–1.0 wt‐%), sn‐1,2‐diacylglycerols (1,2‐DAG; 0.4–1.2 wt‐%) and phospholipids (PL; 49.4–58.8 wt‐%). Fatty acids derivatized as methyl esters were analyzed by gas chromatography (GC) and a flame ionization detector. Molecular species and the fatty acid distribution of TAG isolated from the total lipids in the beans were analyzed by a combination of argentation‐TLC and GC. A modified argentation‐TLC procedure, developed to optimize the separation of the complex mixture of total TAG, provided 18 different groups of TAG, based on both the degree of unsaturation and the total length of the three acyl chains of fatty acid groups. SDT (3.2–4.2 wt‐%), M₂T (3.8–5.0 wt‐%), D₃ (4.8–5.9 wt‐%), MDT (8.0–13.9 wt‐%), D₂T (12.5–15.8 wt‐%), MT₂ (19.4–22.7 wt‐%), DT₂ (17.8–23.5 wt‐%) and T₃ (9.2–13.0 wt‐%) were the main TAG components. The dominant fatty acids of TAG were α‐linolenic (48.5–57.8 wt‐%) and linoleic (16.7–25.8 wt‐%) acids, with appreciable amounts of palmitic (8.3–13.2 wt‐%) and oleic (7.8–13.8 wt‐%) acids. The high content of α‐linolenic acid in the cultivars of P. vulgaris could very likely play a beneficial role in reducing the risk of coronary heart disease among the large populations consuming them in Japan.     

Virgin hemp seed oil: An interesting niche product

Virgin hemp seed oil is not widespread on the market, although it is characterised by an interesting fatty acid composition with a high content of polyunsaturated fatty acids. Linoleic acid is the predominant fatty acid, which comes, together with α‐linolenic acid (18:3n‐3), to approximately 80% of the total fatty acids. From a nutritional point of view, up to 7% γ‐linolenic acid (18:3n‐6) and 2.5% stearidonic acid (18:4n‐3) are very interesting. The total amount of tocopherols is high between 80 and 110 mg/100 g, with γ‐tocopherol as the main tocopherol (85%). Due to the high amount of unsaturated fatty acids, hemp seed oil is very susceptible to oxidative deterioration, which results in a fast impairment of the oil during storage. In addition, the high amounts of chlorophyll in the oil due to harvesting of high amounts of immature seeds require light protection, which is often neglected because of merchandising purposes. The virgin oil is characterised by a nutty taste with a slightly bitter aftertaste. The use of virgin hemp seed oil is recommended during mild processing of food without heat.     

Oxidative stability of natural and randomized high-palmitic-and high-stearic-acid oils from genetically modified soybean varieties

The oxidative stability of soybean oil triacylglycerols (TAG) obtained from genetically modified soybeans was determined before and after chemical randomization. Soybean oil oxidative studies were carried out under static oxygen headspace at 60°C in the dark and oxidative deterioration was monitored by peroxide value, monometric and oligomeric oxidation products, and volatile compounds. Randomization of the soybean oil TAG improved the oxidative stability compared to the natural soybean oil TAG. Oxidative stability was improved by three factors. Factor one was the genetic modification of the fatty acid composition in which polyunsaturated acids (such as linolenic and linoleic acids) were decreased and in which monounsaturated fatty acids (such as oleic) and saturated acids (palmitic and stearic) were increased. Factor two was the TAG compositional modification with a decrease in linolenic and linoleic-containing TAG and an increase in TAG with stearic and palmitic acids in combination with oleic acid. Factor three was the TAG structure modification accomplished by an increase in saturated fatty acids and a decrease in linoleic and linolenic acids at the glycerol moiety carbon 2. Presented at the AOCS Annual Meeting & Expo, Chicago, IL, May 10–13, 1998.     

Analysis of Fatty Acid and Lignan Composition of Indian Germplasm of Sesame to Evaluate Their Nutritional Merits

An attempt was made to individually analyze a germplasm collection of 54 indigenous Indian sesame cultivars for fatty acid and lignan composition of their seed oil by gas chromatography and high performance liquid chromatography, respectively. The entries varied in their fatty acid and lignan composition. The mean percentage contents of palmitic, stearic, oleic, linoleic and α‐linolenic acids ranged between 10–22, 5–10, 38–50, 18–43 and less than 1 whereas sesamol, sesamin and sesamolin scored between 3–37, 27–67, 20–59 of the total percentage of lignan, respectively. The highest percentage of α‐linolenic acid (ALA) was obtained in Var‐9 (1.3 % of the total fatty acids). Among the lignans, high sesamin content is considered to be significant, particularly in terms of long shelf life and nutraceutical value of sesame seed oil. The study has broadened our understanding related to differential biochemical composition of the rich sesame germplasms, thereby providing us with a useful groundwork for identifying potential targets and suitable cultivars for genetic engineering approaches to be undertaken in order to improve the nutritional quality of sesame oil, which in turn would be beneficial towards human health.     

Chemical Compositions of Walnut (Juglans regia L.) Oils from Different Cultivated Regions in China

This study is a comprehensive report on the quality of Chinese walnut oil, which enriches the research of oil resources. A total of 16 walnut samples from China were selected, and walnut oils were obtained using the pressing process. The lipid compositions and micronutrient contents were analyzed. The fatty acids corresponded to palmitic acid (3.05–8.25%), oleic acid (12.56–26.03%), linoleic acid (51.21–68.97%), and linolenic acid (6.83–15.01%), and the main triacylglycerols were trilinolein (27.87–39.47%), followed by oleoyl‐linoleoyl‐linolenoyl‐glycerol (17.07–24.18%), dilinoleoyl‐oleoyl‐glycerol (9.65–15.46%), palmitoyl‐dilinoleoyl‐glycerol (5.96–14.98%), and dilinoleoyl‐linolenoyl‐glycerol (6.42–12.43%). In addition, high amounts of micronutrients, including phytosterol, squalene, tocopherol, and total phenolic content, were found in walnut oils ranging from 540 to 1594, 17 to 131, 345 to 1280, and 1.04 to 20.39 mg kg^?1 among different samples, respectively. The differences in the geographical location and climate caused different regions of cultivation, which resulted in the differences in the chemical composition of walnut oil. Further multiple linear regression analyses between oxidative stability indices, fatty‐acid compositions, and micronutrients revealed that linoleic acid (R = ?0.891; P < 0.05), α‐tocopherol (R = 0.713; P < 0.05), and total phenolic content (R = 0.369; P < 0.05) were the main factors that affect the oxidative stability of the walnut oil.     

Effects of conjugated linolenic acid and conjugated linoleic acid on lipid metabolism in mice

The effects of two isomers of conjugated linolenic acid (CLnA), α‐eleostearic acid (α‐ESA) and punicic acid (PA), on body fat and lipid metabolism were investigated, compared with a conjugated linoleic acid (CLA) mixture (primarily cis9,trans11‐ and trans10,cis12‐18:2) and α‐linolenic acid (ALA), a non‐conjugated octadecatrienoic acid, in the present study. ICR mice were fed either a control diet or one of four experimental diets supplemented with 1% α‐ESA, 1% PA, 1% CLA mixture and 1% ALA in the form of triacylglycerols (TAG) for 6 weeks. The weights of perirenal and epididymal adipose tissues were significantly decreased while the liver weight was significantly increased in mice fed CLA, compared with the control. In contrast to CLA, the tissue weights in α—ESA‐, PA‐ and ALA‐fed mice were not affected. No significant differences were observed in TAG, total cholesterol, high‐density lipoprotein and low‐density lipoprotein cholesterol levels among the five groups. The liver TAG level was significantly decreased in mice fed α‐ESA and PA while it was significantly increased in mice fed the CLA mixture. These results indicate that CLnA and CLA have differential effects on body fat mass and liver TAG levels in mice.     

Lipase‐mediated hydrolysis of flax seed oil for selective enrichment of α‐linolenic acid

Polyunsaturated fatty acids (PUFA) are important ingredients of human diet because of their prominent role in the function of human brain, eye and kidney. α‐Linolenic acid (ALA), a C18, n‐3 PUFA is a precursor of long chain PUFA in humans. Commercial lipases of Candida rugosa, Pseudomonas cepacea, Pseudomonas fluorescens, and Rhizomucor miehei were used for hydrolysis of flax seed oil. Reversed phase high performance liquid chromatography followed by gas chromatography showed that the purified oil contained 12 triacylglycerols (TAGs) with differences in fatty acid compositions. Flax seed oil TAGs contained α‐linolenic acid (50%) as a major fatty acid while palmitic, oleic, linoleic made up rest of the portion. Among the four commercial lipases C. rugosa has preference for ALA, and that ALA was enriched in free fatty acids. C. rugosa lipase mediated hydrolysis of the TAGs resulted in a fatty acid mixture that was enriched in α‐linolenic to about 72% yield that could be further enriched to 80% yield by selective removal of saturated fatty acids by urea complexation. Such purified ALA can be used for preparation of ALA‐enriched glycerides. Practical applications : This methodology allows purifying ALA from fatty acid mixture obtained from flax seed oil by urea complexation.     

Oxidative stability of Echium plantagineum seed oil bodies

Echium plantagineum seed contains a highly polyunsaturated oil (approximately 14% linoleic acid, 10% γ‐linolenic acid, 33% α‐linolenic acid and 14% stearidonic acid); almost half of the fatty acids are omega‐3 fatty acids, so there is an interest in the possible health benefits of this oil, which, once extracted, is prone to oxidation. For the first time in reported literature, oil bodies (OBs), the organelles that store the oil in mature seed, were recovered from E. plantagineum seeds. The oxidative stability of these organelles ex vivo, dispersed in an aqueous continuous phase, was tested against processed E. plantagineum oil emulsions stabilised with either SDS or Tween 20. For both primary and secondary oxidation products the OBs were the most stable form of dispersed oil, and the dispersed systems were all more stable than bulk E. plantagineum oil after incubating at 40°C for 7 days. The possible reasons for the enhanced chemical stability of E. plantagineum OBs are explored in this paper. Practical applications: OBs, the natural store of oil in oilseeds, can be recovered from seeds intact and are relatively stable to oxidation ex vivo. Echium seed OBs, enriched in physiologically active omega‐3 fatty acids, therefore offer an attractive alternative to traditional oil extraction methods and overcome the need to encapsulate the omega‐3 rich oil.     

Effects of Vegetable Oil Composition on Epoxidation Kinetics and Physical Properties

In this article, we investigate the role of triacylglycerol composition on the properties of epoxidized vegetable oils and the kinetics of the epoxidation process under conditions comparable to commercial epoxidation. Commodity soybean oil (24% oleic acid, 50% linoleic acid, and 7% linolenic acid), high‐oleic soybean oil (75% oleic acid, 8% linoleic acid, and 2.5% linolenic acid), and linseed oil (11% oleic acid, 15% linoleic acid, and 64% linolenic acid) were each epoxidized to various extents. Epoxidation rate, viscosity, differential calorimetry, and X‐ray diffraction data are presented for these oils and interpreted in the context of their fatty acid profile (mostly oleic, linoleic, or linolenic). While fully epoxidized soybean oil is widely commercially available and used in an increasing array of industrial applications, information relating to partially epoxidized oils and epoxidized oils of other cultivars is less well known.     

Triacylglycerols of Apiaceae seed oils: Composition and regiodistribution of fatty acids

Oils from the seeds of caraway (Carum carvi), carrot (Daucus carota), celery (Apium graveolens) and parsley (Petroselinum crispum), all from the Apiaceae family, were analyzed by gas chromatography for their triacylglycerol (TAG) composition and fatty acid (FA) distribution between the sn‐1(3) and sn‐2 positions of TAG. Twenty‐two TAG species were quantified. Glyceryl tripetroselinate was the major TAG species in seed oils of carrot, celery and parsley, with levels ranging from 38.7 to 55.3%. In caraway seed oil, dipetroselinoyllinoleoylglycerol was the major TAG species at 21.2%, while the glyceryl tripetroselinate content was 11.4%. Other TAG species were linoleoyloleoylpetroselinoylglycerol and dipetroselinoyloleoylglycerol. Predominantly, TAG were triunsaturated (72.2–84.0%) with diunsaturates at 14.4–25.9%, and small amounts of monounsaturated TAG. Results for regiospecific analysis showed a non‐random FA distribution in Apiaceae for palmitic, petroselinic, linoleic and oleic acids. Petroselinic acid was predominantly located at the sn‐1(3) position in carrot, celery and parsley seed oils, while it was mainly at the sn‐2 position in caraway seed oil. The distribution of linoleic acid was opposite to that of petroselinic acid. Oleic acid was mostly located at the sn‐2 position, except for caraway, where it was evenly distributed between the sn‐1(3) and sn‐2 positions. Both the saturated FA, palmitic and stearic acid, were located mainly at the sn‐1(3) position. The presence of a high level of tripetroselinin in parsley seed oil (55.3%) makes it a potential source for the production of petroselinic acid.     

Dietary trans α‐linolenic acid does not inhibit Δ5‐ and Δ6‐desaturation of linoleic acid in man

Dietary trans monoenes have been associated with an increased risk of heart disease in some studies and this has caused much concern. Trans polyenes are also present in the diet, for example, trans α‐linolenic acid is formed during the deodorisation of α‐linolenic acid‐rich oils such as rapeseed oil. One would expect the intake of trans α‐linolenic acid to be on the increase since the consumption of rapeseed oil in the western diet is increasing. There are no data on trans α‐linolenic acid consumption and its effects. We therefore carried out a comprehensive study to examine whether trans isomers of this polyunsaturated fatty acid increased the risk of coronary heart disease. Since inhibition of Δ6‐desaturase had also been linked to heart disease, the effect of trans α‐linolenic acid on the conversion of [U‐¹³C]‐labelled linoleic acid to dihomo‐γ‐linolenic and arachidonic acid was studied in 7 healthy men recruited from the staff and students of the University of Edinburgh. Thirty percent of the habitual fat was replaced using a trans ‘free’‐ or ‘high’ trans α‐linolenic acid fat. After at least 6 weeks on the experimental diets, the men received 3‐oleyl, 1,2‐[U‐¹³C]‐linoleyl glycerol (15 mg twice daily for ten days). The fatty acid composition of plasma phospholipids and the incorporation of ¹³C‐label into n‐6 fatty acids were determined at day 8, 9 and 10 and after a 6‐week washout period by gas chromatography‐combustion‐isotope ratio mass spectrometry. Trans α‐linolenic acid of plasma phospholipids increased from 0.04 ? 0.01 to 0.17 ? 0.02 and cis ? ‐linolenic acid decreased from 0.42 ? 0.07 to 0.29 ? 0.08 g/100 g of fatty acids on the high trans diet. The composition of the other plasma phospholipid fatty acids did not change. The enrichment of phosphatidyl ¹³C‐linoleic acid reached a plateau at day 10 and the average of the last 3 days did not differ between the low and high trans period. Both dihomo‐γ‐linolenic and arachidonic acid in phospholipids were enriched in ¹³C, both in absolute and relative terms (with respect to ¹³C‐linoleic acid). The enrichment was slightly and significantly higher during the high trans period (P<0.05). Our data suggest that a diet rich in trans α‐linolenic acid (0.6% of energy) does not inhibit the conversion of linoleic acid to dihomo‐γ‐linolenic and arachidonic acid in healthy middle‐aged men consuming a diet rich in linoleic acid.     

Borage and evening primrose oil

The paper gives a short overview about the production and composition of borage (Borago officinalis) and evening primrose (Oenothera biennis) oil considering special aspects of the production as cold‐pressed oil. Both oils are characterized by a remarkable amount of γ‐linolenic acid, which has some nutritional advantages. The fatty acid composition of evening primrose oil is dominated by linoleic acid with about 72% and about 13% γ‐linolenic acid, while borage oil consists of twice the amount of γ‐linolenic acid and only 38% linoleic acid. The amount of saturated fatty acids is higher in borage oil. The tocopherol composition of both oils is dominated by γ‐tocopherol, with borage oil containing twice the amount compared to evening primrose oil.     

Extraction and Characterization of Montmorency Sour Cherry (Prunus cerasus L.) Pit Oil

Montmorency sour cherry (Prunus cerasus L.) pit oil (CPO) was extracted and characterized by various methods including: GC, LC–MS, NMR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X‐ray powder diffraction (XRD). The oil gave an acid value of 1.45 mg KOH/g, saponification value of 193 mg KOH/g and unsaponifiable matter content of 0.72 %. The oil contained oleic (O) and linoleic (l ) acids as the major components with small concentrations of α‐eleostearic acid (El, 9Z,11E,13E‐octadecatrienoic acid) and saturated fatty acid palmitic (P) acid. The CPO contained six major triacyglycerols (TAG), OOO (16.83 %), OLO (16.64 %), LLO (13.20 %), OLP (7.25 %), OOP (6.49 %) and LElL (6.16 %) plus a number of other minor TAG. The TAG containing at least one saturated fatty acid constitute 33 % of the total. The polymorphic behavior of CPO as studied by DSC and XRD confirmed the presence of α, β′ and β crystal forms. The oxidative induction time of CPO was 30.3 min at 130 °C and the thermal decomposition temperature was 352 °C.     

Content and Fatty Acid Composition of Neutral Acylglycerols in Euonymus Fruits

The content and fatty acid (FA) composition of FA neutral acylglycerols (NAG), a mixture of 1,2,3-triacyl-sn-glycerols (TAG) and 3-acetyl-1,2-diacyl-sn-glycerols (acDAG), were determined in the seeds and arils of fruits of 14 Euonymus L. species. On the average, the seeds exceeded the arils in the absolute and relative dry matter content 2.9- and 1.9-fold, respectively, and separate plant species greatly differed in NAG composition. The proportions of TAG in the NAG of seeds and arils were 4–5 and ~98 %, respectively. The degree of FA unsaturation in aril NAG was higher than in the seed NAG, and in acDAG—higher, than in TAG. In the NAG, 14 major FA molecular species (excluding minor FA) were found, and linoleic, oleic, palmitic, and linolenic acids were predominant. NAG of separate taxonomic units of the genus Euonymus L. differed from each other in the concentration of major FA as well as other FA. So, by using statistical analysis, it was definitely established that the species from the subgenus Euonymus were characterized by an increased content of linoleic acid, while those from the subgenus Kalonymus, by the predominance of oleic acid. Meanwhile, the species of the section Euonymus were marked by an enhanced concentration of a number of hexa- and octadecenoic FA positional isomers.     

Characterization of volatile compounds and triacylglycerol profiles of nut oils using SPME‐GC‐MS and MALDI‐TOF‐MS

Several nut oil varieties mainly used as culinary and overall healthy food ingredients were subject of the present study. Headspace solid‐phase microextraction combined with gas chromatography‐mass spectrometry was employed in order to determine the qualitative composition of volatile compounds. Furthermore, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry was used in order to assess the profiles and relative composition of the prevalent triacylglycerols (TAG) within the oils. The headspace of the majority of oil samples was dominated by high contents of acetic acid (up to 42%) and hexanal (up to 32%). As nut oils are typically gained by cold‐pressing from previously roasted nuts, characteristic pyrazine derivatives as well as degradation products of long‐chain fatty acids were detected. TAG analysis of these oils revealed a quite homogeneous composition dominated by components of the C₅₂ and C₅₄ group composed mainly of oleic (18:1), linoleic (18:2), stearic (18:0) and palmitic (16:0) acid residues representing together between 65 and 95% of the investigated nut oils. The TAG profiles showed characteristic patterns which can be used as ‘fingerprints’ of the genuine oils. Nut oils exhibiting quite similar fatty acid composition (e.g. hazelnut, pistachio and beech oil) could be clearly discriminated based on TAG showing significant differences between the oils.     

Developmental changes in fatty acid composition of oil in kernel fractions of corn (Zea mays L.)

Gas liquid chromatography was used to determine the change in fatty acid composition of oil from three kernel fractions (pericarp, endosperm and germ) during kernel maturation of four inbred lines of corn. Inbred lines were sibpollinated, and sampling of ears began six days after pollination (DAP) and continued at three day intervals until 33 DAP and then at weekly intervals until 54 DAP. Proportion of palmitic acid in the pericarp oil rapidly decreased between 6 and 12 DAP while oleic and linoleic acids increased during the same period. Changes in fatty acid composition of oil from the endosperm during kernel maturation were erratic and no consistent trends were evident. In the germ oil, palmitic and linolenic acid proportions decreased during kernel maturation, while oleic acid decreased and linoleic acid increased during kernel maturation for three of the four inbred lines. By about 24 to 27 DAP, the fatty acid composition of oil in the mature kernel was established. Since kernel fractions are of different genetic origin, a study of developmental changes in lipid classes or in fatty acid composition of oil should be limited within kernel fractions that have a similar genetic constitution. Approved as Journal Series Paper No. 723, University of Georgia, College of Agriculture Experiment Stations.     

Analysis of volatile compounds and triacylglycerol composition of fatty seed oil gained from flax and false flax

Linseed (Linum usitatissimum, L.) and camelina (Camelina sativa, L.) are ancient crops containing seed oils with a high potential for nutritional, medicinal, pharmaceutical and technical applications. In the present study, linseed and camelina oils of plant varieties grown under Central European climate conditions were examined with respect to their volatile and triacylglycerol (TAG) components. Solid‐phase microextraction was applied to the study of volatile compounds of several linseed and camelina oils, which have not been described prior to this publication. Hexanol (6.5–20.3% related to the total level of volatiles), trans‐2‐butenal (1.3–5.0%) and acetic acid (3.6–3.8%) could be identified as the main volatile compounds in the linseed oil samples. Trans‐2‐butenal (9.8%) and acetic acid (9.3%), accompanied by trans,trans‐3,5‐octadiene‐2‐one (3.8%) and trans,trans‐2,4‐heptadienal (3.6%), dominated the headspace of the examined camelina oil samples. TAG were analysed by MALDI‐RTOF‐MS and ESI‐IT‐MS, providing information about the total TAG composition of the oils as well as the fatty acid composition of the individual components. More than 20 TAG could be identified directly from whole linseed oil samples, mainly composed of linolenic (18:3), linoleic (18:2) and oleic (18:1) acid, and to a lesser degree of stearic (18:0) and palmitic (16:0) acid. While in linseed these TAG comprise more than 60% of the oils, Camelina sativa exhibited a wider range of more than 50 constituents, with a considerable amount (>35%) of TAG containing gadoleic (20:1) and eicosadienoic (20:2) acid.     

Stability of pumpkin seed oil

In Austria pumpkins are grown primarily for the production of pumpkin seeds that can be used for eating or the production of salad oil. Pumpkin seed oil is dark green and its fatty acid composition consists typically of linoleic acid and oleic acid as the dominant fatty acids. The saturated fatty acids palmitic and stearic acid occur at lower levels. The samples for this study were taken from a breeding program that intends to increase the seed and oil productivity. 15 samples with different contents of linoleic acid (40—57%) and vitamin E (100—600 μg/g) were selected. The stability of the oil was measured in a Rancimat that oxidizes the oil at 120 �C and measures the induction time that is needed for the oxidation. The correlation analysis showed that only the ratio of linoleic acid to oleic acid had a significant influence on the oxidative stability of the oil. Vitamin E did not show any correlation. When α‐tocopherol was added to the oil a strong pro‐oxidative effect was observed.     

Searching for health beneficial n‐3 and n‐6 fatty acids in plant seeds

Various plant seeds have received little attention in fatty acid research. Seeds from 30 species mainly of Boraginaceae and Primulaceae were analysed in order to identify potential new sources of the n‐3 PUFA α‐linolenic acid (ALA) and stearidonic acid (SDA) and of the n‐6 PUFA γ‐linolenic acid (GLA). The fatty acid distribution differed enormously between genera of the same family. Echium species (Boraginaceae) contained the highest amount of total n‐3 PUFA (47.1%), predominantly ALA (36.6%) and SDA (10.5%) combined with high GLA (10.2%). Further species of Boraginaceae rich in both SDA and GLA were Omphalodes linifolia (8.4, 17.2%, resp.), Cerinthe minor (7.5, 9.9%, resp.) and Buglossoides purpureocaerulea (6.1, 16.6%, resp.). Alkanna species belonging to Boraginaceae had comparable amounts of ALA (37.3%) and GLA (11.4%) like Echium but lower SDA contents (3.7%). Different genera of Primulaceae (Dodecatheon and Primula) had varying ALA (14.8, 28.8%, resp.) and GLA portions (4.1, 1.5%, resp.), but similar amounts of SDA (4.9, 4.5%, resp.). Cannabis sativa cultivars (Cannabaceae) were rich in linoleic acid (57.1%), but poor in SDA and GLA (0.8, 2.7%, resp.). In conclusion, several of the presented plant seeds contain considerable amounts of n‐3 PUFA and GLA, which could be relevant for nutritional purposes due to their biological function as precursors for eicosanoid synthesis. Practical applications: N‐3 PUFA are important for human health and nutrition. Unfortunately, due to the increasing world population, overfishing of the seas and generally low amounts of n‐3 PUFA in major oil crops, there is a demand for new sources of n‐3 PUFA. One approach involves searching for potential vegetable sources of n‐3 PUFA; especially those rich in ALA and SDA. The conversion of ALA to SDA in humans is dependent on the rate‐limiting Δ6‐desaturation. Plant‐derived SDA is therefore a promising precursor regarding the endogenous synthesis of n‐3 long‐chain PUFA in humans. The present study shows that, in addition to seed oil of Echium, other species of Boraginaceae (Cerinthe, Omphalodes, Lithospermum, Buglossoides) and Primulaceae (Dodecatheon, Primula), generally high in n‐3 PUFA (30–50%), contain considerable amounts of SDA (5–10%). Therefore, these seed oils could be important for nutrition.