Classification of vegetable oil
Vegetable oils are classified based on their ability to absorb oxygen from the atmosphere.
They are usually classified into four main groups.
- Drying oils
- Semi-drying oils
- Non-drying oils.
- Vegetable fats.
They readily absorb atmospheric oxygen when exposed and form a dry thin elastic film.
They are fairly rich in unsaturated fatty acids, especially linoleic and linolenic acids.
They have a high iodine number (more than 130).
They are particularly used in paint and varnish industries.
Linseed oil (Linum usitatissimum- Linaceae)
Safflower oil (Carthamus tinctorius- Asteraceae)
Poppy oil (Papaver somniferum- Papaveraceae)
Soyabean oil (Glycine max – Fabaceae)
They are intermediate between drying and non-drying oils and characterized by
They absorb atmospheric oxygen slowly and produce a soft film even after long exposure.
They are rich in linoleic and saturated acids but do not contain linolenic acid.
Semi-drying oil has an iodine number between 100 to 130.
They are edible oils, also as an illuminant, and in making soap and candles.
Cottonseed oil (Gossypium Spp-Malvaceae)
Sesame oil (Sesamum indicum Pedaliaceae)
Rape and Mustard oil (Brassica spp – Brassicaceae)
Sunflower oil (Helianthus annuus – Asteraceae)
These oils do not absorb atmospheric oxygen and as such are incapable of forming elastic films even after long exposure
They are rich in saturated acids and oleic acid and either contain small amounts or no linoleic or linolenic acids
Non-Drying oils have an iodine number less than 100.
They are particularly useful in the manufacture of soaps, as lubricants, and as food.
Groundnut oil (Arachis hypogea – Fabaceae)
Castor oil (Ricinus communis Euphorbiaceae)
Olive oil (Olea europaea Oleaceae)
Vegetable Fats / Tallow
Fats are solid or semisolid at room temperature.
They are fairly rich in saturated fatty acids. c) Vegetable fats have a low iodine number between 8-50.
They are edible, in the soap and candle-making industries.
Palm oil (Elaeis guineensis Arecaceae)
Cocoa butter (Theobroma cacao Sterculiaceae)
Mohua fat (Madhuca indica – Sapotaceae)