Major fatty acids linolenic

The major fatty acids present in plant-derived fatty substances are oleic acid (9-octadecenoic, C18 l), linoleic acid (9,12-octadecadienoic, C18 2) and the conjugated isomers thereof and linolenic acid (9,12,15-octadecatrienoic, C18 3) (Scheme 31.1). Their rates of oxygen absorption are 100 40 1, respectively, hence partial hydrogenation with consequent lowering of the iodine number would lead to a significant increase in oxidative stabihty, particularly when C18 3 is reduced. 

The development of a characteristic, objectionable, beany, grassy, and hay-like flavor in soybean oil, commonly known as reversion flavor, is a classic problem of the food industry. Soybean oil tends to develop this objectionable flavor when its peroxide value is still as low as a few meq/kg, whereas other vegetable oils, such as cottonseed, com, and sunflower, do not (15, 51). Smouse and Chang (52) identified 71 compounds in the volatiles of a typical reverted-but-not-rancid soybean oil. They reported that 2-pentylfuran formed from the autoxidation of linoleic acid, which is the major fatty acid of soybean oil, and contributes significantly to the beany and grassy flavor of soybean oil. Other compounds identified in the reverted soybean oil also have fatty acids as their precursors. For example, the green bean flavor is caused by c/i-3-hexenal, which is formed by the autoxidation of linolenic acid that usually constitutes 2-11% in soybean oil. Linoleic acid oxidized to l-octen-3-ol, which is characterized by its mushroom-like flavor (53). 

Table 7 shows the fatty acid composition of different citrus seed oils. The ratio of unsaturated to saturated fatty acids is approximately 2 1 (9), although this ratio was reported to be in the range of 3-5 1 by Nagy (35). Generally, different varieties, cultivar, location, storage condition, and harvesting time of citrus fruit may lead to this variation. Table 8 shows the content of the six major fatty acids in different citrus seed oils these are linoleic (C18 2), palmitic (C16 0), oleic (C18 l), linolenic (C18 3), stearic (C18 0), and palmitoleic (C16 l) acids. 

The cherry tree Prunus avium L.) is a member of the Rosaceae family. Cherry seed contains about 18% oil on a dry weight basis (48). Significant levels of oleic acid were detected in the cherry seed oils prepared by hexane extraction using a Soxhlet apparatus. Oleic acid comprised 24—38% of the total fatty acids from three different varieties of cherry fruits (Table 7) (48). Linoleic acid was the major fatty acid in the cherry seed oil, and ranged 40 9% in the seed oil, along with ot-eleostearic (18 n-5), palmitic, stearic, arachidonic, and ot-linolenic acids (Table 7). alpha-eleostearic acid comprising 10-13% of cherry seed oil, is a conjugated... 

Com oil is composed of fatty acid esters with glycerol, known commonly as triglycerides. Typical com oil produced in the USA contains five major fatty acids linoleic 58.9% oleic 25.8% palmitic 11.0% stearic 1.7% and linolenic 1.1%. Com grown outside the USA yields com oil with lower linoleic, higher oleic, and higher saturated fatty acid levels. Corn oil also contains small quantities of plant sterols. 

Major fatty acid compositions" (% w/w) Palmitic acid 4.14 Stearic acid 1.57 Oleic acid 35.86 Linoleic acid 19.75 Linolenic acid 7.77 Erucic aicd 12.90... 

In comparison to other vegetable sources, avocado oil is characterized by its contents of palmitic (C16 0), linoleic (C18 2), palmitoleic (16 1) and alpha-linolenic (18 3) FAs that are 13.5, 12.6, 3.26 and 1.0 % of total fatty acids, respectively. Stearic (18 0), tridecanoic (13 0), tetradecanoic (14 0), cA-lO-heptadecenoic (17 1) and c/s-13-16-eicosenoic (20 2) FAs are present in trace amounts [49]. Ozdemir and Topuz [50] showed in Fuerte and Hass avocado varieties present a reduction of palmitc acid according to fruit ripening, with variations of 22.4-12 % to Fuerte variety and 23.3-16.8 % to Hass variety. Yanly et al. [51] studying three Malaysia avocados varieties, found oleic acid as the major fatty acid (43.65-51.22 %) followed by palmitic (26.41-30.37 %) and linoleic (12.75-17.45 %) FAs. Oils of avocado fruits are generally found to have extremely low amounts of stearic acid (0.27-1.56 %). 

Jimg et al. [4] conducted extraction with near and SC CO2 of wheat bran and found that the major fatty acids present in the extracted oil were palmitic, oleic, linoleic and y-linolenic acids. They only considered the yield change with time, not the compositional change. However, as seen in 6.2 below, partial fractionation of the oil may be possible. 

Linolenic acid is the major fatty acid of plant leaves, stems and roots and is also a significant component of other photosynthetic organisms. See Hil-ditch and Williams (1964). 

Although the number of fatty acids detected in plant tissues approaches 300, most of them only occur in a few plant species (Hitchcock and Nichols, 1971). The major fatty acids are all saturated or unsaturated monocarboxylic acids with an unbranched even-numbered carbon chain. The saturated fatty acids, lauric (dodecanoic), myristic (tetradecanoic), palmitic (hexadeca-noic), and stearic (octadecanoic), and the unsaturated fatty acids, oleic (cis-9-octadecenoic), linoleic (c/5 -9,cw-12-octadecadienoic), and linolenic (all-cij-9,12,15-octadecatrienoic (Table I), together account for almost all of the fatty acid content of higher plants. For example, about 94% of the total fatty acids of commercial oils and 89-97% of leaf fatty acids consist of these seven structures alone. It will be noted that the unsaturated acids all contain a cis-9 double bond and that the polyunsaturated acids contain a methylene-interrupted structure. The four saturated fatty acids differ from each other by two carbons. These structural relationships are due to the principal pathways of fatty acid biosynthesis in plants (see Stumpf, this volume. Chapter 7). 

In contrast, other types of storage tissue—corns, tubers, bulbs—accumulate low amounts of fats. The major types of lipids in these tissues are phospholipids and glycolipids, and they contain the same major fatty acids. Although the actual distribution of fatty acids varies somewhat, palmitic, linoleic, and linolenic are the most abundant. A few examples of distributions are given in Table XI. The division between lipid-rich and other tissues is somewhat vague, but 10% dry weight and above is probably a reasonable... 

The oil content of four Egyptian citrus seeds revealed levels ranging from 40.2 to 45.4% for orange, mandarin, lime and grapefruit. Palmitic, oleic and linoleic acids were the major fatty acids in all oils. The lime oil content, however, showed unusually high levels of linolenic acid (42.2%) (Habib etal, 1986). 

Azima tetracantha is a flowering shrub that grows in India with a seed oil content of 12% (Daulatabad et al., 1991). Major fatty acids are linoleic (28.8%), linolenic acid (22%) and oleic acid (15.3%), with smaller amounts of palmitic (5.2%), myristic (4.2%), lauric (3.5%) and stearic (1.6%). This seed contains three unusual fatty acids ricinoleic (9.8%), malvalic (4.0%) and sterculic (5.6%). 

The comparison of labelling patterns of fatty acids acids of PC and DGG (Fig. 2A and 3A) showed that for the first hours of incorparation (until 12h) the linoleic acid of PC accumulated little or none radioactivity while both the linoleic and linolenic acids of DGG were largely labelled.This finding Suggested that oleic acid could be the major fatty acid donated by PC to DGG... 

The plasma membrane-enriched fractions of the T, deformans reference cells contained membrane-bound vesicles typical of such fractions (Weete et al., 1985b). The major fatty acids of these membranes were those expected for this fungus (Sancholle, 1984 Weete et al., 1983), i.e. palmitic, stearic, oleic, linoleic and linolenic acids (Table 1). The A/mole was relatively low at 0.84 which indicated that the lipids of these membranes had a relatively high amount of saturated fatty acids. Brassica-sterol and an unidentified C28 diene were detected as previously reported for this species at 84.5% and 15.5%, respectively (Weete et al., 1985a). 

Oleic, linoleic and linolenic acids were the major fatty acids in the extracted canola oil. There was a decrease in relative concentrations of oleic (C18 l (0-9) and linolenic acid when ethanol was added as a cosolvent while oleic (C18 l co-7) and linolenic acid concentrations increased significantly p < 0.01). Use of ethanol resulted in extraction of C16 l which is not present when SC-CO2 is used alone. Longer chain fatty acids (C20 0, C22 0 and C22 l) were not present in the SC-CO2 extracts when canola flakes were used as the starting feed material. However, these longer chain fatty acids were present in the extracted oil when ethanol was included as a cosolvent and press cake was the feed material. The extraction of phospholipids using ethanol as a cosolvent, without need for degumming, provides opportunity for the cosmetics and food industry that has yet to be fully exploited. 

In r. pyriformis grown on a fat-free mediiun, Y-luaolenic acid, 18 3 (6,9,12), was the major fatty acid (37.7%), together with 18 2 and 18 1. There was no a-linolenic add and no Ci polyenoic fatty add, and only traces of C20 unsaturated fatty acids. These findings were substantially confirmed by the chromatographic analyses of Shorb (1961) and her colleagues (Pollard et al., 1964). GLC analysis provided no evidence for the presence of the saturated and unsaturated C22 and C24 fatty acids reported in T. pyriformis by McKee et al. (1947). 

Galactolipids, sulfonolipids and phospholipids are universally found in ferns (491, 492). The major fatty acid components of these lipids are palmitic (16 0), oleic (18 1, 9), linoleic (18 2, 6, 9) and linolenic (18 3, 3, 6, 9) acids (493, 494, 495, 498). Fern lipids differ from those of angiosperms in having arachidonic acid (841) and related polyunsaturated C2o-fatty acids (494,495,498) which are usually found only in animals and microorganisms. (5)-8-Hydroxyhexadecanoic acid... 

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