Unsaturated fatty acids oxidative scission

TABLE 12. Scission Products from Unsaturated Fatty Acids Oxidized at Room Temperature. (Data from 3, 8, 273, 290, 314, 340, 341, 345, 347-349.)... 

Monohydroperoxides are the primary products of lipid oxidation. A variety of hydroperoxides with positional and geometrical isomers are formed depending on the position and number of double bonds of the unsaturated fatty acids and the oxidation mechanism. A number of reviews have been published on the composition of isomeric hydroperoxides formed from oxidation of oleate, linoleate, and linolenate (286, 287-291). The hydroperoxides formed are odorless, but they are relatively unstable and are the precursors of a variety of volatile and nonvolatile scission products that are important to the oxidized flavor. 

Vegetable oils usually offer two major reactive sites for their conversion into polyols. These are the double bonds present in the unsaturated fatty acids and the ester groups which link the fatty add to the glycerol moiety. Polyols may be prepared by direct oxidation of the double bonds present in vegetable oils which contain sufficient unsaturation (linseed, safflower, soybean, tobacco, etc.). However, control of oxidation is difficult as it produces a number of oxidation by-products such as peroxides, aldehydes, ketones, carboxyls and other low molecular weight spedes which are produced by chain scission. In addition, the presence of high unsaturation in these polyols makes the product susceptible to oxidation which results in changes of colour and properties over time. 

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