ABSTRACT
Omega 3 and omega 6 fatty acids are chemically classi‚ed as polyunsaturated fatty acids. As is common to fatty acids, they consist of a hydrocarbon chain with a hydrophilic carboxylic acid group at the “alpha” terminus and a hydrophobic methyl group at the “omega” terminus. As a polyunsaturated fatty acid, omega 3 and omega 6 fatty acids have more than one carbon-carbon methylene-interrupted cis double bonds in the hydrocarbon chain. The “omega 3” designates that the carbon-carbon double bond located closest to the omega terminus is in the third position, whereas the double bond is in the sixth position for the “omega 6” fatty acids (Figure 32.1). This terminus labeling re‘ects a bias of mammalian fatty acid metabolism and biochemistry as typical mammalian enzymology is not capable of introducing carboncarbon double bonds in the omega 3 and omega 6 positions. Chemical-based nomenclature would locate the carbon-carbon double bonds using the “alpha” carboxy terminus as the reference point, and given that the “alpha” end of the molecule is the site of carbon addition (elongation) and removal (β-oxidation), an omega-3 bond in an 18-carbon fatty acid would be in the Δ15 position, in a 20-carbon fatty acid it
32.1 Introduction .................................................................................................................................. 725 32.2 Omega 3 and Omega 6 Polyunsaturated Fatty Acids .................................................................. 727 32.3 Food Supply ................................................................................................................................. 729 32.4 Chemical Occurrence of Omega 3 and Omega 6 Fatty Acids within Food ................................ 730 32.5 Analytical Challenge .....................................................................................................................731
