Flax oil and high linolenic oils

Roman Przybylski University of Manitoba, Winnipeg, Manitoba, Canada, Canola Oil, Flax Oil and High Linolenic Oils. 

Refined, bleached and deodorized. Adapted from Przybylski, R., 2005 Flax oil and high linolenic oils. In Shahidi, F. (Ed.), Bailey s Industrial Oil and Fat Products. John Wiley Sons, Inc., Hoboken, NJ, pp. 281 -298. ... 

Many species in the Europhorbiaceae and Labiatae families produce seeds with a high content of oil and contribution of hnolenic acid of up to 76% (1). Flaxseed has been used for years in the production of paints, varnishes, inks, and linoleum. In food applications, flaxseed is more often used than oil because of its better stability and because of the presence of fiber, lignans, and a-linolenic acid (ALA), which have health benefits. Cold pressed flaxseed oil is not considered suitable for deep-frying, although Chinese use it in stir-frying (2). In this chapter, oilseeds of flax, perilla, camelina, and chia are discussed as sources of oils with elevated content of ALA. These oilseeds are produced in industrial quantities and can be considered as potential sources of new oils with specific nutritional and functional properties. 

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 seed of perilla contains 31-51% of oil, which is similar in composition to flaxseed oil, with a higher contribution of PUFA of over 70% (Table 4). The oil is highly unsaturated, with an iodine value of 192-208-g iodine /100-g oil (Table 4). Perilla oil contains over 60% linolenic acid with equal amounts of both linoleic and oleic acids (Table 4). Specific gravity of this oil is higher than flax oil because of a higher contribution of PUFA. Other physical parameters of this oil reflect the composition of its fatty acids. 

Chia oil is high in polyunsaturated fatty acids, particularly a-linolenic acid the content of this fatty acid is higher than flax oil (Table 4). Linoleic acid is the second-most abundant acid in chia with a contribution of 17-26%, which gives PUFA content of 83%, the highest amount among edible oils. Additionally, chia oil has the lowest content of saturated fatty acids (Tables 2 and 4). 

Linolenic acid is also important industrially it is the major constituent of linseed oil (approximately 47%) which is obtained from flax. The high degree of unsaturation present in this acid makes the oil an excellent drying agent for use in paints, varnishes and inks. 

Different varieties of flax Linum usitatissimum) are grown for fiber and for oil. Linseed oil is well known as one of the most unsaturated vegetable oils, resulting from its high level of linolenic acid (50-60%, Table 4). As a consequence of this, it oxidizes and polymerizes very readily and is used in paints, varnishes, and inks, in the production of linoleum, and as a sealant for concrete. These uses diminished with the appearance of alternative petroleum-based products, but the natural oil is coming back into favor on environmental grounds (33). 

Linseed Oil. Flax, used for fiber and seed production and the subsequent processing of the seed into linseed oil, is grown mainly in Canada, China and India (cf. Table 14.0). Due to its high content of linolenic acid (cf. Table 14.11), the oil readily autoxidizes, one of the processes by which some bitter substances are created. Since autoxidation involving polymerization reactions proceeds rapidly, the oil solidifies Jast drying oir). Therefore, it is used as a base for oil paints, varnishes and linoleum manufacturing, etc. A comparatively negligible amount, particularly of the coldpressed oil, is utilized as an edible oil. 

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