The enigma of the trans fatty acids

Abstract

Margarines and shortenings, man made equivalents of butter and lard, contain different amounts of partially hydrogenated vegetable oils. As described in the preceding chapter, the partial hydrogenation of vegetable oils, such as corn and soybean, modifies the chemical and physical properties of their fatty acids. Partial hydrogenation, for example, transforms some fatty acids into new compounds called fatty acid isomers. We have already distinguished between positional and geometrical isomers of unsaturated fatty acids in Chapter 1. Geometrical isomers are illustrated in Fig 3 in which it is seen that the cis-isomers are curved at the point of unsaturation, while the trans-isomers are linear. The natural vegetable oils contain only cis-isomers, while the partially hydrogenated oils contain variable amounts of trans-isomers.