Introduction
Among agricultural crops, seeds use for the extraction of fixed oils are rated in economic and commercial importance second only to cereals. Fixed oils are obtained from fruit pericarps and in some instances such as the palm, Elaeis guineensis (palmae), two oils differing in properties and chemical composition are obtained- the palm kernel oil from the endosperm and the palmoil from the orange yellow fleshy pericarp.
A naturally occurring mixture of lipids such as olive oil or oil of theobroma may be either solid or liquid hence the term “oil” or fat ceases to have any significance.
Identification tests for fats and fixed oils
- Oils and fats are soluble in ether-alcohol but with the exception of castor oil which is sparingly soluble.
- Fats and oils are coloured black or brown with 1% solution of osmic acid.
- Fats and oils are coloured red with a dilute tincture of alkanna.
- A cold mixture of equal parts of a saturated solution of potash and strong solution of ammonia slowly saponifies fixed oils and fats.