Plants use stored oil as food for germinating embryo, caloric content is high so is efficient storage material. Oil can be stored in endosperm, cotyledons, scutellum (corn), fruit pulp (palms and olives)

Oils are a mixture of triglycerides and free fatty acids. In triglycerides, glycerol is the backbone.

Free Fatty Acids + Glycerol = Triglycerides

The number of double bonds determines the level of saturation.

Vegetable oils are complex mixtures and saturation levels cannot be calculated directly very easily; % saturation is determined by Iodine method, I breaks ='s and is incorporated. Amount of I left over is determined. I values range from 7 to >200. 70 are called fats (solid at room temperature) and higher values correspond to more unsaturation.

Drying - >150 thin film will dry into impervious coating
Semidrying - 100-150
Nondrying - 70-100
Fats 70

Nonfood uses

Soap - Na and K salts of fatty acids produced by reacting NaOH or KOH with triglycerides

Oil Paints and varnishes - from drying or semidrying oils (linseed & tung oil) - oil paints are boiled with heavy metal containing compounds (Mg, Co, Pb) which help oils absorb oxygen and form a hard film; varnishes are produced by mixing boiled oils with resins or gums; enamels are varnishes + pigments; paints do not contain gums or resins

Latex paints - alkyd resins which are manufactured from fatty acids cleaved from vegetable oils, water soluble

Linoleum - Oils + gums + synthetic resins + pigments; oils are "blown" which thickens them and makes them soluble in petroleum oils (resins); linoleum is not used much in U.S. anymore.

Other industrial oils
Jojoba - oils is esters rather than triglycerides, originally thought to be good substitute for sperm oil but is not because of high temperature breakdown; however is useful in medicine and cosmetics.

Extraction

1. Grinding with stones
2. Steam driven stone press
3. Screw press - continuous feed
4. Solvent extraction - follows screw press, hexane


Refining
1. Removal of free fatty acids
2. Degumming - removes mucilagenous material
3. Bleaching - removal of pigments
4. Deodorized - steam heating
5. Winterize - prevents clouding by chilling oil and filtering out particles.
6. Hydrogenation - yields vegeatable lards, margarine and cheese substitutes

Drying Oils

Linseed oil - Linum usitatissimum, seeds, also source of flax, water-repellent glaze, mostly non-edible oils due to unpleasant flavor and rapid rancidity due to lots of double bonds.

Tung oil - Aleurites (Euphorbiaceae), seeds, poisonous, used in paints, waterproof coverings and caulking. Once grown in U.S. but most now comes from China.

Semi-drying Oils

Safflower oil - Carthamus tinctorius, thistles, oil is from seeds, used in cooking oils, salad dressings, margarine, high I value so low in calories but oxidizes readily

Soybean oil - already covered, stores well, used in salad and cooking oils and artificial "fluffy" products.

Sunflower oil - Helianthus annuus - native North American plant but development of large-headed cultivars is largely credited to Russians; used as salad and cooking oil; paints, varnishes and resins; added to diesel fuel.

Corn oil - salad dressing and margarines, stable but smokes at high temp.

Sesame oil - Sesamum indicum, from Ethiopia, highly resistant to oxidation, most is consumed and produced in Africa, Middle East, India and China

Cottonseed oil - byproduct of cotton fiber production, must remove gossypol (toxic to most animals except cows); Wesson oil, hydrogenation ---> Crisco

Rapeseed oil - Brassica napus, edible oil but possibly toxic, most useful as machine oil


Non-drying Oils

Peanut oil - Arachis hypogaea, premium cooking oil

Olive oil - Olea europea, obtained from fruit pulp, one oil that is not refined to death so retains unique flavor.

Castor oil - Ricinus communis - laxative, poison, contains ricine (alkaloid) and ricin (highly toxic protein); used in soaps, paints, lubricants

Vegetable Fats

Oil palms - Elaeis guineensis, distinct oils are obtained from fruit pulp and seeds, are kept separate due to differences in chemical composition; used in soap, candles, margarine and shortenings but U.S. diets are avoiding fats and palm oils are taboo.

Coconut oil - Cocos nucifera, cosmetics and nondairy "dairy" products

Waxes

Plant leaves have thin layer of wax for protection from environment
Carnauba wax - Copernicia cerifera - used in car waxes and polishes

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