High erucic acid rape

Table 2.4 Fatty acid profile (% by weight) of oil from conventional and high erucic acid rape (HEAR) cultivars (Padley et ah, 1994)...

The relationship between the six brassica species has been described by Downey et al., (1975). Commercially grown high-erucic acid rape and mustard seed oil are similar in composition and are characterized by their high erucic acid content (McPherson, 1978 Tsunoda era/., 1980). 

The glyceride composition of mustard oil has not been reported but presumably is similar to that of high-erucic acid rape (Table 3.94). 

Until the early 70s high-erucic acid rape had been used freely in a number of countries for edible purposes. Biological tests on animals have highlighted potential dangers to the heart in humans. As a... 

Saturated acids with an even number of carbon atoms per molecule are usually isolated by distillation of esters from an appropriate source. These include esters from lauric-rich oils (Cio, C12, C14), palm oil and cottonseed oil (C16), hydrogenated animal fats and seed oils (Cig) and hydrogenated high-erucic acid rape oil (C22). These acids are commercially available in high purity at a reasonable cost. 

Erucic acid (22 113c) is available from high-erucic acid rape oil by distillation and crystallization. 

Currently available cultivars of high erucic acid rape (HEAR) have a theoretical maximum of 66% erucic acid (22 1, A13) in their seed oil due to the specificity of the membrane-bound l-acyl-572-glycerol-3-phosphate acyl transferase (LPA-AT) enzyme. In HEAR the LPA-AT does not incorporate erucic acid at the sn-2 position of triacylglycerols (TAG) but preferentially incorporates oleic acid (18 1, A9), even if this is only a minor component of the total fatty acid pool (1). However, some plant species, Q.g Limnanthes, can utilise erucoyl-CoA as a substrate and effectively incorporate erucic acid at the sn-2 position (2, 3). 

LEAR, low erucic acid rape seed oil. HEAR, high erucic acid rape see oil. 

To study the membrane associated enzymes involved in elongation in oil seed rape Brassica napus), a high erucic acid rape (HEAR) variety was used. Low erucic acid rape variety contains a mutation which prevents elongation of 018 1 fatty acids. As the nature of the mutation is not known, and could be in the elongating enoyl reductase, HEAR was used throughout these studies. 

Metz, J.G., Pollard, M.R., Anderson, L., Hayes, T.R., Lassner, M.W., 2000. Purification of a jojoba embryo fatty acyl-coenzyme A reductase and expression of its cDNA in high erucic acid rape-seed. Plant Physiol. 122, 635-644. 

McVetty, P.B.E., W.G.D. Fernando, R. Scarth, and G. Li. 2006a. Red River 1826 Roundup Ready high erucic acid low glucosinolate summer rape. Canadian Journal of Plant Science 86 1179-1180. 

The magnitude of the variation in the composition of rapeseed oil and meal now commercially available has created a need for new terms to describe the products derived from rapeseed. The fatty acid composition of most edible vegetable oils such as soybean, sunflower, or cottonseed oils, varies within narrow limits. Thus, the species or commodity name (e.g., soybean oil) provides a reasonable description of the fatty add composition of soybean oil. In contrast, the erucic acid content of commercially available rapeseed oil may vary from near zero to 55%, and the oleic acid from 10 to more than 60%. A number of terms have been proposed or utilized to describe the new rapeseed oil whose fatty acid composition has been altered by the elimination of erucic acid these include low erucic acid rape-seed oil (LEAR), canbra, and canola. Similar terms such as high erucic acid rapeseed oil (HEAR) and common or traditional rapeseed oil have been used to describe rapeseed oil whose fatty acid composition includes substantial amounts of erucic acid. 

The elimination of erucic acid from rapeseed oil resulted in an increase in the linoleic acid content of the oil from approximately 13 to 21%. Further increases appear to be possible since the values as high as 50% have been reported. However, such values do not appear to be stable and were not recovered in progeny tests (Jonsson, 1977a). Values up to at least 30% linoleic are stable, that is, are under genetic control. Some variation in linoleic acid content seems to occur in many populations of low erucic acid rape-seed. Since a reduction in component fatty acids other than oleic and linoleic provide greater opportunity for variation in these components, it may be desirable to select for increased linoleic acid content in populations low in both erucic and linolenic acids and thus to add this characteristic after reduced levels of linolenic have been achieved. 

The high erucic acid rapeseed oil has been used industrially for example as a lubricant (erucamide) and as a source of brassylic (C13 dicarboxylic acid, tridecanedioic acid) and pelargonic (nonanoic acid) acids via ozonolysis. Low-erucic acid rape is also used as a lubricating and cutting oil and, after hydrogenation, in soap. 

Interest in the Brassicaceae as an oilseed for industrial oils uses has largely been as a consequence of erucic acid content in the oil and the high protein meal left over after oil extraction (Robbelen, 1991) Several Brassica oilseed species including B. carinata, B. juncea, B. nigra, B. napus (oilseed rape/ rapeseed) and B. rapa naturally produce seed oil with medium-to-high erucic acid content and medium-to-high protein meal after oil extraction (Downey and Robbelen, 1989). Erucic acid content in the seed oil of these species. 

By way of a specific example let us consider erucic acid. The main commercial source of erucic acid is a specially bred form of rape seed (HEAR) as pointed out above. With European consumption being around 60 000 tpa almost 40 000 ha of land are used to grow rapeseed for erucic acid production in Europe. The high level of erucic found in this type of rape seed oil make it unsuitable for human consumption, owing to the indigestibility of such large amounts of this acid. Erucic acid is also the major fatty acid to be found in nasturtium and crambe seeds (up to 75% and 56% respectively), and it is also found in the salad herb, rocket. 

Most commodity oils contain fatty acids with chain lengths between Cie and C22, with Cig fatty acids dominating in most plant oils. Palm kernel and coconut, sources of medium-chain fatty acids, are referred to as lauric oils. Animal fats have a wider range of chain length, and high erucic varieties of rape are rich in this C22 monoene acid. Potential new oil crops with unusual unsaturation or additional functionahty are under development. Compilations of the fatty acid composition of oils and fats (6, 9, 11, 12) and less-common fatty acids (13) are available. 

The above list does not include cocoa butter nor minor oils such as rice bran oil or safflower oil. Nor does it distinguish between oils from a common botanical source with a modified fatty acid composition, such as canola oil and high-erucic rape seed oil, linseed oil and linola, or the various types of sunflower oil. 

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