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Vegetable Oils Where is the oil located? • Plants use stored oil as food for germinating embryo, caloric content is high so is efficient storage material. Double that of carbohydrates and proteins. • Oil can be stored in endosperm (castor, coconut), cotyledons (peanut, soybean), scutellum (corn), fruit pulp (palms and olives). • Seeds have organelles called as glyxosomes that convert fatty acids into carbohydrates during germination. Oils • Mainly hydrocarbons made up of – Glycerol (backbone) with three fatty acids chemically bonded to it - triglycerides Cholesterol Unsaturation • 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, • Iodine breaks ='s and is incorporated. Amount of Iodine left over is determined. Iodine values range from 7 to >200. 70 are called fats (solid at room temperature) and higher values correspond to more unsaturation. Unsaturation and Iodine Value • Drying - >150 thin film will dry into impervious coating • Semidrying - 100-150 • Nondrying - 70-100 • Fats 70 http://discovermagazine.com/2001/mar/featchemistry/ Soap making • Soap is salt of fatty acid +3NaOH 3 RCOONa+ + Soap Making • Water lye (Base) • Add oil or fat – Glycerol and fatty acids separate – Fatty acids will react with base to form salt of fatty acid – Head which is soluble in water – Tail soluble in oil Oil Paints and Varnishes • 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 and Jojoba • Made up of 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. • 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 • Grinding with stones - cold pressing – high quality • Steam driven stone press – hot pressing • Screw press - continuous feed • Solvent extraction - follows screw press, hexane Refining • • • • • Removal of free fatty acids Degumming - removes mucilaginous material Bleaching - removal of pigments Deodorized - steam heating Winterize - prevents clouding by chilling oil and filtering out particles. • Hydrogenation - yields vegetable lards, margarine and cheese substitutes Drying Oils High in double bonds in FA • Linseed oil - Linum usitatissimum, seeds, waterrepellent glaze – mostly non-edible oils • due to unpleasant flavor • Cyanogenic glycosidesand • rapid rancidity due to lots of double bonds. – also source of flax • Tung oil - Aleurites (Euphorbiaceae), seeds, poisonous (not edible), used in paints, waterproof coverings and caulking. Once grown in U.S. but most now comes from China. Semi-drying Oil Few double bonds in FA • 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 – • • • • • • Produces dye Soybean oil – Glycine max 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. Considered equal to olive oil, used for production of margarines. Corn oil – Zea mays salad dressing and margarines, stable but smokes at high temp. Sesame oil - Sesamum indicum, from Ethiopia, highly resistant to oxidation due an antioxidant compound called sesamolin, most is consumed and produced in Africa, Middle East, India and China Cottonseed oil – Gossypium barbedensis 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 as an lubricant Non-drying Oil • Peanut oil - Arachis hypogaea, premium cooking oil • Olive oil - Olea europea, obtained from fruit pulp, – Gentle pressing of the olive – virgin oil – Further pressing – first, second grade oils – Has monounsaturated fat – good for health. • Castor oil - Ricinus communis – Laxative – ricinoleic acid – poison - ricine (alkaloid) and ricin (highly toxic protein); used in soaps, paints, lubricants Vegetable Fat • Oil palms - Elaeis guinensis, distinct oils are obtained from fruit pulp and seeds – kept separate due to differences in chemical composition; used in soap, candles, margarine and shortenings – U.S. diets are avoiding fats and palm oils are taboo. • Coconut oil - Cocos nucifera, cosmetics and nondairy "dairy" products – At 20oC becomes semisolid; at 15oC becomes brittle – Has free fatty acid – caprylic acid - smell • Shea butter: Butyrospermum parkit – 50% saturated fat Relative effect of fats on Total Cholesterol Myristic acid C14:0 Palmitic acid C16:0 Linoleic acid C18:2 Alpha Linolenic Acid C18:3 Dietary Cholesterol Butterfat 11 27 2 1 273 1788 Canola oil 0 4 22 10 0 -514 18 9 2 0 0 1674 Corn oil 0 11 58 1 0 -870 Grape seed oil 0 8 73 0 0 -1196 Lard 2 26 10 0 77 630 Olive oil 0 13 10 1 0 88.6 Safflower oil* 0 7 78 0 0 -1310 Soybean oil 0 11 54 7 0 -908 Sunflower oil* 0 7 68 1 0 -1142 Oil or Fat Coconut oil * Not high-oleic Delta TC Change in cholesterol level Wax • Long chain alcohol and long chain fatty acid • Jojoba wax: Simmondsia chinensis – Seeds contain liquid wax – Similar to sperm whale oil