Agriculture Reference
In-Depth Information
Figure
2.17.
Examples of the components of lipids, glycerol, unsaturated, Z (cis), E (trans) fatty
acids, and triglyceride.
Table 2.6 gives the common polyunsaturated fatty acids. As noted, they all have
more than one double bond and docoshexenoic acid has six double bonds. It is
common that these double bonds be Z (cis) as indicated in Figure 2.17. Increasing
the double-bond content of fatty acids decreases their melting point, and thus they
are liquids at room temperature and below. Double bonds can be removed by a
process called hydrogenation, which results in fatty acids that remain solid at room
temperature. This is advantageous when producing butter substitutes. However, trans
fatty acids are produced during hydrogenation, and there is increasing data that indi-
cates that trans fatty acids are deleterious to health and should be avoided (http://
www.hsph.harvard.edu/reviews/transfats.html).
Although the body can make most fatty acids from any food source, there are two,
octadecadienoic and octadectrienoic, acids that are essential fats. This means that they
