Fatty acid composition of canola oil

The stigma of the erucic acid (22 1 n-9) in rapeseed oil has lingered, despite firm evidence that this fatty acid is more of a threat to rats than to humans. It is sufficient to say that the discovery of chain-shortening of erucic acid to oleic acid by peroxisomes was a fundamental breakthrough in the understanding of fatty acid metabolism in the past few decades. Once in the oleic acid form, the erucic acid residue is as readily catabolized by mitochondria as are palmitic and other fatty acids (Ackman 1990). The fall in the level of erucic acid in rapeseed oil resulted in a marked increase in Cis acids and they make up around 95% of all fatty acids present in canola oil (Table 4.2). 

Fatty acid Canola HEAR LLCAN HOCAN LTCAN GLCO Llflax Soybean SUN 

Abbreviations LLCAN - low-linolenic acid canola oil HOCAN - high-oleic acid canola oil GLCO - canola oil with gamma linolenic acid LLFlax - flaxseed oil with reduced content of linolenic acid LTCAN - canola oil with high content of lauric acid MUFA - monounsaturated fatty acids PUFA -polyunsaturated fatty acids. 

Recently canola oil with a high content of lauric acid (39%) was developed to be used in confectionery coatings, coffee whiteners, whipped toppings and center-filling fats (Table 4.2). Further, canola oil with 40% of stearic acid is available to be used as replacement for hydrogenated fats in bread and bakery markets (Vecchia 1996). Another canola oil containing approximately 10% of palmitic acid for improved crystallization properties has been developed and canola oil for the health food market containing up to 40% of y-linolenic acid is also available (Tso et al. 2001). 

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Table 5. Fatty acid composition of canola oil before and after genetic modification to increase the GLA content...

Nutritional Impact of Fatty Acid Composition of Canola Oil and Its Effect on the Oxidative Deterioration... 

Seedfats are characterized by low contents of saturated fatty acids. They contain palmitic, oleic, linoleic, and linolenic acids. Sometimes unusual fatty acids may be present, such as erucic acid in rapeseed oil. Recent developments in plant breeding have made it possible to change the fatty acid composition of seed oils dramatically. Rapeseed oil in which the erucic acid has been replaced by oleic acid is known as canola oil. Low linolenic acid soybean oil can be obtained, as... 

Edible oils and fats are composed primarily of triacylglycerols (TAG), ester of one molecule of glycerol, and three molecules of fatty acids. Analysis of canola oils showed that TAGs constituted 94.4% to 99.1 % of the total lipid (2). The typical composition of canola, rapeseed, and soybean oils is presented in Table 1. 

Detailed fatty acid composition of canola, soybean, sunflower, corn (maize), and flax oils as well as some specialty canola oils and HEAR oil are given in Table 2. 

These oilseeds have been developed over the past two decades. These oils are very low in linolenic acid (except high oleic canola). All of these oils can be used for industrial frying without hydrogenation. Fatty acid compositions of these oils are listed in Table 6. These oils are in hmited supply and they are expensive. Com oil, cottonseed oil, and palmolein have been included along with the others for comparison. 

Fatty Acid Composition of Canola and Sunflower Oils... 

Jenkins, T.C. (1998) Fatty acid composition of milk from Holstein cows fed oleamide or canola oil. J. Dairy Sci., 81, 794-800. 

Canola Oil Canola oil is obtained from low erucic acid, low glucosinolate rapeseed. The unique polyunsaturated fatty acid and low saturated composition of canola oil differentiates it from other oils. It has a higher oleic acid (18 1) content (55%) and lower linoleic acid (18 2) content (26%) than most other vegetable oils, but it contains 8-12% of linolenic acid (18 3) (58). Canola oil is most widely used in Canada and is considered a nutritionally balanced oil because of its favorable ratio of near 2 1 for linoleic to linolenic acid content. Unlike most other edible oils, the major breakdown products of canola oil are the cis, trans- and tram, trans-2,4-heptadienals with an odor character generally described as oily, fatty, and putty. Stored canola oil shows a sharp increase in the content of its degradation products, which are well above their odor detection thresholds. The aroma is dominated by cis, tram-, tram, frani-2,4-heptadienals, hexanal, nonanal, and the cis, trans- and... 

Sterols are present in canola oil in two forms in equal amounts, free sterols and esterified sterols (19, 37). The fatty acid composition of the esterified sterol fraction in canola oil is shown in Table 7. 

Canola oil is characterized by a low level of saturated fatty acids (less than 4% palmitic acid) and relatively high levels of oleic acid (60%) and a-linolenic acid (10%). It is second only to olive oil, among the common fats and oils, in oleic acid level and, except for soybean oil, the only common dietary fat that contains a significant amount of a-linolenic acid. Furthermore, there is a favorable balance in the levels of linolenic and linoleic acids (viz., 18 3/18 2 ratio of 1 2) in canola oil. Canola oil has been found equally as effective as soybean oil, safflower oil, and sunflower oil in reducing plasma total and LDL cholesterol levels in normolipi-demic subjects. It also was effective in reducing plasma total and LDL cholesterol levels in hyperlipidemic subjects when it replaced saturated fat in their diets. Canola oil diets also have been shown to affect the fatty acid composition of blood... 

Fatty acid composition of regular flax oil is different from other commercial oils because of the very high contribution of ALA, usually above 50% (Table 2). Because of the high content of this unique fatty acid, flaxseed and flax oil are often used as food supplements, where enrichment with omega-3 fatty acids is needed. This fatty acid is susceptible to oxidation it oxidizes 20 0 times faster than oleic acid and 2 times faster than linoleic acid (8). This property makes the oil a good material for paint and plastic production where fast oxidation is required. Flax oil contains low amounts of saturated fatty acids (SFA) compared with low linolenic flax oil (Linola), soybean, and sunflower oils however, it is higher than canola oil (Table 2). Canola oil contains the lowest amount of SFA among all commercial oils. 

The fatty acid composition of the new crop has been modified, and the level of linolenic acid has been reduced from over 50% to 2% (6). This greatly improves oxidative stability of the oil, which by fatty acid composition is very close to sunflower and soybean oils (Table 2). Linola has been found to be more resistant to oxidation than regular flax oil, and its stability is comparable with soybean, canola, and sunflower oils (Przybylski, unpublished data). 

Table 4.7 Fatty acid composition of esterilied sterols in canola oil...

Fig. 10. Fatty acid composition of dietary vegetable oils and beef tallow. The values shown represent typical compositions of varieties grown commercially. Lines modified substantially through breeding or genetic engineering are available for soybean, canola, com, and sunflower.

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