Fats and Oils - Lipids
Fats and oils are energy givers, like carbohydrates. Sources of fats and oils include olive oils, palm oils, groundnut oil, fatty meat, egg yoke, butter, margarine, etc.
Characteristics of fats and oils:
1. They contain high proportion of carbon and hydrogen but very little oxygen.
2. They are bad conductors of heat. They therefore help to insulate the body from cold and keep it warm.
3. Fats and oils are insoluble in water.
4. They are soluble in ether.
5. They are broken down to fatty acids and glycerol before they can be absorbed by the body.
6. Fats are solid at room temperature. Oils are liquid at room temperature.
7. When fats and oil are exposed to air for prolonged period they become rancid. This is spoilage as rancid fats and oils have undesirable flavour and taste.
Effects of heat on fats and oils:
1. Solid fat melts when heated.
3. When fats and oils are heated to very high temperature:
- they burn.
- they can catch fire.
- fumes and unpleasant odour are given out. And these irritate the eyes and are choking.
Tests for fats and oils:
- smear or mark a little of butter or groundnut oil in a sheet of light White paper
- hold up the paper.
Translucent patch is formed by the oil mail.
Sudan III test
- place a small quantity of groundnut paste ( or any other chopped or mashed food substance containing fat) in a test tube.
- add a few drops of Sudan III solution or osmic acid.
- observe the distinct red colouration produced.