Elementary plant Biochemistry and Biotechnology (2+1)

Major fatty acids

• The major fatty acids are saturated or unsaturated with an unbranched carbon chain.
• The saturated fatty acids are lauric (dodecanoic), myristic (tetradecanoic), palmitic (hexadecanoic) and stearic (octadecanoic) acid. The unsaturated fatty acids are oleic (9-octadecenoic), linoleic (9,12-octadecadienoic) and γ-linolenic (9,12,15- octadecatrienoic) acid.
• They are usually found in the lipids from all parts of plants.
• The structure of fatty acids are written as a symbol of two numbers separated by a colon:the first number denotes the carbon atoms in the chain and the second number denotes the number of unsaturation centres.
• The positions of double bonds are specified by superscript numbers following (delta).
• Thus 18:2 (Δ9, 12) indicates an eighteen carbon fatty acid with two double bonds between C-9 and C-10, and between C-12 and C-13.
• The double bonds of all naturally occurring unsaturated fatty acids are in the cis configuration.
• The non-polar hydrocarbon chain accounts for the poor solubility of fatty acids in water.