Sunflower fatty acid distribution

Epoxidized plant oils such as castor oil can also be converted into polyols and copolymerized with isocyanates such as toluenediisocyanate (TDI) or methylene-4,49-diphenyldiisocyanate (MDI) to obtain PUs. Meier et al. [56] reported that canola, corn, soybean, and sunflower oil-derived polyols yield PU resins of similar cross-linking densities (and, consequently, similar glass transition temperatures) and mechanical properties, despite differences in fatty acid distribution. 

The 1,2,3-random hypotheses assumes that one pool of fatty acids is randomly distributed to all three positions of the glycerol molecules in an oil. The fatty acid compositions of the sn-1, sn-2, and in-3-positions would thus be equivalent. Figure 6 shows the theoretical composition of regular sunflower oil as calculated by the equations of random distribution. Calculation of the random distribution was based on the following composition 11% saturated fatty acids (Sat), 20% oleic acid (O), and 69% linoleic acid (L). The TAG composition of a regular sunflower oil determined experimentally is also shown there is no indication of the overall fatty acid composition (17). Differences between both compositions are not great, in particular, taking into account the fact that the fatty acid composition may differ for the oils considered. 

As previously mentioned, the triglycerides found in biomass are esters of the triol, glycerol, and fatty acids (Fig. 3.6). These water-insoluble, oil-soluble esters are common in many biomass species, especially the oilseed crops, but the concentrations are small compared to those of the polysaccharides and lignins. Many saturated fatty acids have been identified as constituents of the lipids. Surprisingly, almost all the fatty acids that have been found in natural lipids are straight-chain acids containing an even number of carbon atoms. Most lipids in biomass are esters of two or three fatty acids, the most common of which are lauric (Cn), myristic (Cu), palmitic (Cia), oleic (Cis), and linoleic (Cis) acids. Palmitic acid is of widest occurrence and is the major constituent (35 to 45%) of the fatty acids of palm oil. Lauric acid is the most abundant fatty acid of palm-kemel oil (52%), coconut oil (48%), and babassu nut oil (46%). The monounsaturated oleic acid and polyunsaturated linoleic acid comprise about 90% of sunflower oil fatty acids. Linoleic acid is the dominant fatty acid in com oil (55%), soybean oil (53%), and safflower oil (75%). Saturated fatty acids of 18 or more carbon atoms are widely distributed, but are usually present in biomass only in trace amounts, except in waxes. 

In another study, Snape and Nakajima [3], using membrane separation for lipids classes in hydrolyzed sunflower oil, observed that free fatty acids permeated the membrane and preferentially concentrated in the permeate, while triglycerides were retained. Mono- and diglycerides showed intermediate behavior that is, they were equally distributed between permeate and retentate. 

Since only the Upid class distribution of total CLA or c9,tl 1-CLA, the major CLA isomer, has been discussed, the following paragraph deals with the distribution of single CLA isomers. Emken et al. (16) investigated the effect of dietary CLA on accretion of t9-18 l, c9,cl2-18 2, tlO,cl2-CLA, and c9,tl 1-CLA and conversion of these fatty acids to their desaturated, elongated, and chain-shortened metabolites. The subjects were six healthy adult women who had consumed normal diets supplemented with 6 g/d sunflower oil or 3.9 g/d of CLA for 63 d. A mixture of deuterium-labeled fl0,cl2-CLA-15,15,l6,l6- 4, c9,Hl-CLA-l4,l4,15,15,17,18-dr6, c9-18 l-11,11,12,12,17,17,18,18- 8, and t9,cl2-18 2-12,13-<, as their ethyl esters, was fed to each subject, and nine blood samples were drawn over a 48-h period. 

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