Agricultural and genetic potentials of cruciferous oilseed crops

Oilseed crops of the Cruciferae are widely adapted and are of particular importance to countries in the northern latitudes. Cruciferous seed oils from the crops, rapeseed, mustard, Camelina, oilseed radish and Crambe, enter edible or industrial markets, or both. The oil-seed meal can be used either as a high protein feed supplement or as an organic fertilizer. The spring and winter forms of the two species of rapeseed,Brassica napus andB. campestris, are commercially the most important. Advances in crop management and plant breeding have resulted in a 40% to 50% increase in seed yield over the past 25 years. In the next 10 to 15 years, application of newer plant-breeding techniques will result in varieties even higher in yield and seed with improved oil and meal quality. Some of the quality improvements will be new patterns in fatty acid composition, higher oil and protein content, lower fiber content, and removal of the undesirable glucosinolate compounds from the meal. The mustard cropsBrassica juncea andB. hirta are important condiment crops which have considerable potential as edible oil sources. Oilseed radish,Raphanus sativus, yields significantly less seed and oil than other cruciferous oil crops but its oil, which contains a low level of erucic acid (3.7%) and a relatively high content of 16-carbon fatty acids (9.3%), may be useful in blending with normal or zero erucic acid rapeseed oils.Camelina sativa or false flax has many desirable agronomic characteristics but the oil of camelina seed contains too high a level of linolenic acid (36%) to penetrate the edible oil market and too low to compete industrially with linseed oil.Crambe abyssinica andC. hispanica are potentially important producers of high erucic acid industrial oils. Factors limiting Crambe development are the high cost of seed transportation due to the high volume to weight ratio of the threshed seed and the need for extra seed processing steps to render the meal suitable as a high protein feed supplement for livestock and poultry. One of 9 papers presented at the Symposium, “Cruciferous Oilseeds,” ISF-AOCS World Congress, Chicago, September 1970. Contribution No. 425, Research Station, Canada Department of Agriculture, Saskatoon, Saskatchewan, Canada.     

Evaluation of fourBrassica germplasm collections for fatty acid composition

A total of 1116 accessions of cultivatedBrassica spp. from four collections were evaluated for fatty acid composition to identify variants which would be useful in plant improvement programs. The accessions included lines ofB. campestris L.,B. napus L.,B. oleracea L. andB. carinata Braun obtained from the USDA collections at Ames, IA, Pullman, WA, and Geneva, NY, as well as the Centre for Genetic Resources-the Netherlands (CGN) at Wageningen, Netherlands. Fatty acid composition of each accession was determined by using gas chromatography. The range, mean, standard deviation and frequency distributions were calculated for the seven primary fatty acids found in the accessions from each collection. Fatty acid profiles of the four species were very similar. Except for levels of erucic acid in the oilseed accessions ofB. campestris andB. napus, only limited economic variation in fatty acid composition was evident. These data suggest that in theseBrassica species the fatty acid profile has been tightly conserved. Estimated energy obtained by β-oxidation of a high erucic acid rapeseed (HEAR) oil was 13.8% higher than for a low erucic acid rapeseed (LEAR) oil. The higher energy levels of oils containing high levels of erucic acid may have played a significant role in survival and adaptation of these extremely small seedBrassica species. This may explain why such limited variation in fatty acid composition was found in these extensive and diverse collections.     

Analysis of hydroxylated fatty acids from plant oils

A novel process has been described recently for the preparation of hydroxylated fatty acids (HOFA) and HOFA methyl esters from plant oils. HOFA methyl esters prepared from conventional and alternative plant oils were characterized by various chromatographic methods (thin-layer chromatography, high-performance liquid chromatography, and gas chromatography) and gas chromatography-mass spectrometry as well as¹H and¹³C nuclear magnetic resonance spectroscopy. HOFA methyl esters obtained fromEuphorbia lathyris seed oil, low-erucic acid rapeseed oil, and sunflower oil contain as major constituents methylthreo-9,10-dihydroxy octadecanoate (derived from oleic acid) and methyl dihydroxy tetrahydrofuran octadecanoates, e.g., methyl 9,12-dihydroxy-10,13-epoxy octadecanoates and methyl 10,13-dihydroxy-9,12-epoxy octadecanoates (derived from linoleic acid). Other constituents detected in the products include methyl esters of saturated fatty acids (not epoxidized/derivatized) and traces of methyl esters of epoxy fatty acids (not hydrolyzed). The products that contain high levels of monomeric HOFA may find wide application in a variety of technical products.     

Lipidchemical Investigation of Some Oilplants for Edible Oil Production Cultivated in Mongolia

Seeds of some oilplants cultivated in Mongolia (rapeseed, sunflower, soya and mustard) were investigated for oil content and fatty acid composition in dependence of their varieties and cultivation regions. Seeds of given oilplant varieties have nearly same fatty acid composition, but they differ in their oil content. The rapeseed oils do not contain erucic acid, but the seed oil of mustard contained 15.5 % eicosenoic acid.     

Minor component fatty acids of common vegetable oils

A combination of gas-liquid chromatography (GLC) and oxidative cleavage on fractions isolated by mercury derivative chromatography has shown the presence of previously unreported minor component fatty acids in olive, soybean, cottonseed, corn, peanut, rapeseed and safflower oil. All of the oils examined contain small amt of saturated acids above arachidic, some as high as hexacosanoic acid.Cis-11-octadecenoic acid was found in amt ranging from 0.5~2.0%.Cis-11-eicosenoic acid is present in the 0.04~1.4% range (rapeseed oil excluded). The tetracosenoic acid present in rapeseed (0.4%) and safflower oil (0.1%) has been identified as thecis-15-tetracosenoic acid. No unusual polyenoic species were detected with the exception of those in rapeseed oil, which contains 0.6% of both 11,14-eicosadienoic and 13,16-docosadienoic acid.     

Component fatty acids of some cruciferae oils

Summary The oils from yellow mustard seed (Brassica alba), black mustard seed (Brassica nigra) of Indian origin, and rapeseed (Brassica Compestris) of unknown origin have been analyzed for their fatty acid composition without preliminary resolution of fatty acids by lead-salt-alcohol or fractional crystallization methods. The results compare very favorably with those determined by other recently developed methods. It may be concluded therefore that this method can be favorably employed for the determination of fatty acid composition of fats containing higher unsaturated acids. Confirmatory evidence has been obtained for the presence of eicosenoic acid in rapeseed oil. The nature and amount of fatty acids of yellow mustard seed oil of Indian origin do not differ in any significant manner from those of other cruciferous seed oils. The present analysis of black mustard seed oil reveals a higher amount of linolenic acid, and the presence of a C₂₀ monoethenoid acid, not heretofore reported. Contribution No. 708 from the Department of Chemistry, University of Pittsburgh. Presented in part at the Spring meeting of the American Oil Chemists’ Society, held in New Orleans, La., May, 1948. Baliga and Hilditch’s paper. “The Component Acids of Rapeseed Oil” (J. Soc. Chem. Ind.67, 258–262 (1948).     

Microdetermination of the major individual isothiocyanates and oxazolidinethione in rapeseed

A method has been developed for the quantitative determination of the major individual thioglucosides (as their aglycones) in rapeseed on a micro scale. The thioglucosides in the meal were hydrolyzed with myrosinase (B.C. 3.2.3.1, thioglucoside glucohydrolase), and the released aglycones were extracted with methylene chloride. The 3-butenyl and 4-pentenyl isothiocyanates were determined by gas-liquid chromatography. The 5-vinyl-2-oxazolidinethione was determined on an aliquot of the same extract by ultraviolet absorption. Five to 20 milligrams of seed or meal were used, and one operator could analyze 24 samples per day. The standard deviation was ±3% for the isothiocyanates and ±6% for the oxazolidinethione. The limit of detection was 0.1 mg per gram of meal for the isothiocyanates and 0.3 mg per gram of meal for the oxazolidinethione. Small amounts of phenylethyl isothiocyanate and two unidentified isothiocyanates were also found.     

Frying stability of soybean and canola oils with modified fatty acid compositions

Pilot plant-processed samples of soybean and canola (lowerucic acid rapeseed) oil with fatty acid compositions modified by mutation breeding and/or hydrogenation were evaluated for frying stability. Linolenic acid contents were 6.2% for standard soybean oil, 3.7% for low-linolenic soybean oil and 0.4% for the hydrogenated low-linolenic soybean oil. The linolenic acid contents were 10.1% for standard canola oil, 1.7% for canola modified by breeding and 0.8% and 0.6% for oils modified by breeding and hydrogenation. All modified oils had significantly (P<0.05) less room odor intensity after initial heating tests at 190°C than the standard oils, as judged by a sensory panel. Panelists also judged standard oils to have significantly higher intensities for fishy, burnt, rubbery, smoky and acrid odors than the modified oils. Free fatty acids, polar compounds and foam heights during frying were significantly (P<0.05) less in the low-linolenic soy and canola oils than the corresponding unmodified oils after 5 h of frying. The flavor quality of french-fried potatoes was significantly (P<0.05) better for potatoes fried in modified oils than those fried in standard oils. The potatoes fried in standard canola oil were described by the sensory panel as fishy.     

Untersuchungen über die Tocopherol- und Tocotrienolzusammensetzung der Samenöle einiger Vertreter der Familie Apiaceae

Tocopherol and Tocotrienol Composition of Seed Oils of Some Representatives of the Apiaceae Family Fatty oils of a number of species from the family Apiaceae are obtained as the by-products of essential oil production from Apiaceae seeds. These oils contain high levels of petroselinic acid and some of these plant species, for example Coriandrum, have been used in plant breeding as a renewable resource. The fatty oils, however, also contain high levels of tocopherols and tocotrienols, a main component being γ-tocotrienol. Because of this, the seed oils of fennel and other Apiaceae show a high oxidative stability. The tocopherol and tocotrienol composition of these seed oils was investigated using HPLC on silica columns with fluorescence detection. Some of these oils contained total tocopherol levels that were higher than those of germ oils.     

γ-Linolenic and stearidonic acids in Mongolian Boraginaceae

Seeds of nine Central Asian species of Boraginaceae were investigated for the first time for their oil content and for the fatty acid composition of their seed oils by capillary gas chromatography. Levels of γ-linolenic acid ranged from 6.6 to 13.0% and levels of stearidonic acid ranged from 2.4 to 21.4% of total seed fatty acids. The seed oil ofHackelia deflexa exhibited the highest stearidonic acid content (21.4%) that has been found so far in nature. Other high contents of this fatty acid were in threeLappula species (17.2 to 18.1%). Seed oils ofCynoglossum divaricatum andAmblynotus rupestris contain considerable amounts ofcis-11-eicosenoic (5.3 to 5.8%) andcis-13-docosenoic acid (7.0 to 9.7%) besides γ-linolenic (10.2 to 13.0%) and stearidonic acid (2.4 to 6.5%), which distinguish these oils from those of other Boraginaceae genera. This paper was presented as a poster at 10th Minisymposium and Workshop on Plant Lipids, Sept. 3–6, 1995, in Berne, Switzerland.     

Nutritional and toxicological evaluation ofHibiscus sabdariffa oil andCleome viscosa oil

Mesta seed oil (Hibiscus sabdariffa), like cottonseed oil, contains cyclopropenoid fatty acids (2.9%) and epoxy fatty acids (2.6%) in addition to normal fatty acids found in vegetable oils.Cleome viscosa (Capparidaceae) seed oil is rich in linoleic acid (70%) and free from any abnormal chemical constituents. Nutritional and toxicological evaluations of these two oils were done by multigeneration breeding studies by feeding the respective oils and groundnut oil as control at 10% level in a 20% protein diet with adequate vitamins and minerals. These studies revealed that rats fed mesta oil had inferior growth and reproductive performance and also had altered liver metabolism. Rats fedC. viscosa oil did not show any abnormal growth or reproductive performance or altered liver lipid levels. Thus, these studies indicate that raw or refined mesta oil may not be suitable for human consumption whereasC. viscosa oil can be used safely by humans.     

Edible protein products from cruciferae seed meals

Rape, crambe and mustard seed are compared with respect to properties of the fixed oil, nature of the mustard oils and properties of the seed protein. Rapeseed (Brassica campestris andB. napus) has benefited greatly from plant breeding; the erucic acid content of the fixed oil and the level of glucosinolates can now be selected. Crambe seed (Crambe abyssinica), however, is still high in erucic acid and in glucosinolates. The glucosinolate patterns of the mustards are naturally simple. Procedures for preparing edible flours and isolates from rape, crambe and mustard seed are described. With mustard (B. hirta, juncea andnigra), the glucosinolate hydrolysis products are volatile and steamstripping yields a bland flour. With rape and crambe seeds, the intact glucosinolates must be removed; aqueous extraction is practicable. The physical, chemical and nutritional properties of some of the meals, flours and isolates prepared from cruciferae seed are described. One of 9 papers presented at the Symposium, “Cruciferons Oilseeds,” ISF-AOCS World Congress, Chicago, September 1970. Contribution No. 165 from the Food Research Institute, Canada Department of Agriculture, Ottawa, Canada.     

High-temperature gas chromatography for the detection of trierucoylglycerol in the seed oil of transgenic rapeseed (Brassica napus L.)

A method for the determination of the triacylglycerol (TAG) composition of the seed oil of rapeseed (Brassica napus L.) by high-temperature gas chromatography (HT-GC) has been developed. For oil quality breeding in rapeseed such a method gains increasing importance since by means of molecular gene transfer novel TAG species, e.g. like trierucoylglycerol are developed, for the detection of which, however, no adequate efficient method is available. The HT-GC method is quicker in comparison to the conventionally used HPLC method and the analysis can be performed with minute amounts of oil, as they are available by means of oil extraction from single cotyledons of microspore-derived embryos and from ‘half-seeds’ of rapeseed. Following the triacylglycerol analysis, enough oil remains to allow the determination of the fatty acid composition of the same sample.     

Recent developments and perspectives of industrial rapeseed breeding

Due to substantial progress in breeding and cultivation practice rapeseed has become the world's third most important source of vegetable oil. Modification of the fatty acid composition to make rapeseed oil more competitive in various segments of the food and industrial oil markets has been an important objective of plant breeding and molecular genetics in recent years. While making up the primary demand by food and animal feed industry furnished by “double-low” quality rapeseed, so-called “canola”, interest increased to produce “Biodiesel” feedstocks or special materials being directed to several industrial niche markets, because of their higher value than commodity oils. Rapeseed oil is unique in having a large spectrum of usability and good properties for non-food applications, such as relatively homogeneous composition, high degree of refinement, freedom from contaminants, and also biodegradability, giving it advantages over petrochemicals. Consequently, one of the most important objectives of rapeseed breeding is the genetic modification of the seed oil by maximizing the proportion of specific fatty acids, like laurate, erucate or functionalized acids, in order to obtain tailor-made raw materials suited for industrial purposes.     

The occurrence of 6,9,12,15-octadecatetraenoic acid inEchium plantagineum seed oil

The seed oil ofEchium plantagineum, a mem-ber of the borage family, has been shown to contain two polyunsaturated fatty acids not com-monly found in vegetable oils: all-cis-6,9,12-octa-deeatrienoic acid and all-cis-6,9,12,15-octadeca-tetraenoic acid. Prior to their discovery in the Boraginaceae, nonconjugated tetraenoid acids were not known to occur in oils of higher plants. A laboratory of the No. Utiliz. Res. and Dev. Div., ARS, USDA.     

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.     

Vegetable oil raw materials

Vegetable oils that are important to the chemical industry include both edible and industrial oils, which contribute 24% and 13.5%, respectively, compared to 55% for tallow, to the preparation of surfactants, coatings, plasticizers, and other products based on fats and oils. Not only the oils themselves but also the fatty acids recovered from soapstock represent a several billion pound resource. Coconut oil is imported to the extent of 700-1,000 million pounds per year. Its uses are divided about equally between edible and industrial applications. Safflower oil has a relatively small production, but 15–25% of the oil goes into industrial products. Soybean oil, the major edible oil of the world, is produced in the United States at the rate of 11,000 million pounds per year with more than 500 million pounds going into industrial uses, representing 5% of the total production. Castor oil is imported to the extent of about 100 million pounds per year. Linseed oil production has declined drastically over the last 25 years but still amounts to about 100 million pounds per year. Oiticica and tung oils are imported in lesser amounts than castor and linseed oils. New crops that have industrial potential, as well as the traditional vegetable oil crops, include seed oils from crambe,Limnanthes, Lesquerella, Dimorphotheca, Vernonia, andCuphea plants. Crambe oil contains up to 65% erucic acid. Oil fromLimnanthes contains more than 95% of fatty acids above C₁₈.Lesquerella oil contains hydroxy unsaturated acids resembling ricinoleic acid from castor oil.Dimorphotheca oil contains a conjugated dienol system.Vernonia oils contain as much as 80% epoxy acids. TheCuphea oils contain a number of short chain fatty acids. Of these, crambe,Limnanthes, andVernonia are probably the most developed agronomically. Competition between vegetable oils and petrochemicals for the traditional fats and oil markets has been marked over the past 25 years, but prices for petrochemicals have accelerated at a greater rate than those for vegetable oils; and, it is now appropriate to reexamine the old as well as the new markets for fatty acids.     

Studies of Oils of Unusual Fatty Acids

Studies of linseed, castor seed and Vernonia anthelmintica seed oils have been undertaken together keeping in view their industrial importance. Linseed oil contains the highest percentage of linolenic acid (69.1%) whereas the highest percentage of hydroxy fatty acid (85.6%) and epoxy fatty acids (76.8%) has been found out in castor seed and Vernonia anthelmintica seed oils respectively as determined by the application of thin-layer and gas liquid chromatography.     

Factors affecting the composition of canadian oil seeds

Importance of climate, plant breeding, and economics to production of oil seeds in Canada is considered. The influence of temperature and rainfall on the oil content and fatty acid composition of linseed and rapeseed is discussed. Major changes in the fatty acid composition of rapeseed oil can be effected by modern techniques in plant breeding and selection, i.e. erucic acid content can be reduced from approximately 40% to 0. The impact on the oil meal market of continued selection for high oil in crops and varieties is discussed.     

An unusual fatty acid pattern inEranthis seed oil

The current discussion on “renewable resources”, and the possibility of gene transfer into rapeseed, has led to many investigations into the biosynthetic pathways leading to industrially useful fatty acids. The various tribes and genera of the plant familyRanunculaceae contain a large variety of unusual fatty acids. Seed fatty acid patterns differ considerably from genus to genus and are chemotaxonomically significant indicators.Eranthis seed oil has now been found to contain a fatty acid pattern that deviates significantly from the eleven different fatty acid patterns that had been described in this plant family. The main fatty acid (up to 57%) is 13-cis, 16-cis-docosadienoic acid. Other, minor fatty acids found are Δ5-cis-monoenoic,-dienoic, and-trienoic fatty acids that had already been reported to be constituents of the genus-specific seed oil fatty acid patterns of various genera from this plant family. Capillary gas-liquid chromatographic retention data indicate that 22:3Δ5cis, 13cis, 16cis is probably also present. Seed fatty acid chemotaxonomic evidence thus points to a different position ofEranthis within the tribes of this plant family. These findings again indicate that the plant familyRanunculaceae would be an ideal object to study fatty acid biosynthesis and phylogenetic evolution, because in other genera of this family other types of desaturation and chain elongation mechanisms predominate.