Presentation on theme: "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."— Presentation transcript:
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
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 > 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 Nondrying Fats 70
Soap making Soap is salt of fatty acid +3NaOH 3 RCOO- Na+ +
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, water- repellent 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 20 o C becomes semisolid; at 15 o C becomes brittle –Has free fatty acid – caprylic acid - smell Shea butter: Butyrospermum parkit –50% saturated fat
Relative effect of fats on Total Cholesterol Oil or Fat Myristic acid C14:0 Palmitic acid C16:0 Linoleic acid C18:2 Alpha Linolenic Acid C18:3 Dietary Cholesterol Delta TC Change in cholesterol level Butterfat Canola oil Coconut oil Corn oil Grape seed oil Lard Olive oil Safflower oil* Soybean oil Sunflower oil* * Not high-oleic
Wax Long chain alcohol and long chain fatty acid Jojoba wax: Simmondsia chinensis –Seeds contain liquid wax –Similar to sperm whale oil