Fatty acid
- Each fatty acid consists of long hydrocarbon
chain with a carboxyl group (-COOH) at one end.
-Fatty acids are either saturated or unsaturated.
Saturated fatty acids have no double bonds
between the carbon atoms. Unsaturated fatty
acids have double bonds in the carbon chain.
- The unsaturated fatty acids have lower melting
points than the saturated fatty acids.
- Room temperature is 250C, Stearic acid
(saturated fatty acids) which melts at 700C is still
a solid, while Oleaic acid (unsaturated fatty
acids) has melted at 130C, so it is a liquid at room
temperature.
-In making a fat, three fatty acids each join to glycerol by an ester linkage, a bond between
a hydroxyl group and a carboxyl group.
-Since there are three fatty acids per glycerol molecule, the fat molecule is sometimes
called a triglyceride.
- Triglycerides containing unsaturated hydrocarbon chains melt at a lower temperature than
those containing saturated chains.
- Most animal fats are saturated. Saturated animal fats are solid at room temperature. In
contrast, the fats of plants and fishes are generally unsaturated. Usually liquid at room
temperature, plant and fish fats are referred to as oils.