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Fats and oils.ppt

  1. 1. Fats and Oils Mr. P.S.Kore Assistant Professor(Research Scholar) Department of Pharmaceutical Chemistry RCP, Kasegaon.
  2. 2. Contents o FATTY ACIDS: REACTIONS. o HYDROLYSIS o HYDROGENATION o SAPONIFICATION o RANCIDITY OF OILS o DRYING OF OILS o ANALYTICAL CONSTANTS: o ACID VALUE o SAPONIFICATION VALUE o ESTER VALUE o IODINE VALUE o ACETYL VALUE o REICHERT MEISSL (RM) VALUE
  3. 3. Fats And Oils o A lipid can be defined as naturally and chemically occurring substance that is insoluble in water and soluble in alcohol, ether, and chloroform. o The types of lipids involved include Bile salts, Eiosanoids, Glycolipids, Ketone bodies, Phospholipids, Sphingolipids, Steroids and Cholesterols. o Lipids are fats that are either absorbed from blood or synthesized by the liver. o Triglycerides and cholesterol contribute most of diseases. o Waxes: Waxes are esters of long-chain fatty acids and long chain monohydric alcohols, each containing 16 to 34 carbon atoms.
  4. 4.  They are produced from plants and animals, also melts between 350C-1000C.  It is insoluble in water but soluble in organic solvents like.  Various types of waxes:  1. Bees wax: obtained from honeycomb of the bee.  It melts at 620C-650C and used for boot polishes, cosmetic creams, lipsticks, floor and furniture polishes and candles.  2. Carnauba Wax: derived from leaves of carnauba palm native in brazil, melts at 80-870 C and used for boot polishes, coating on mimeograph stencils and carbon papers.  3.Supermaceti Wax: obtained from head-cavity of the sperm whale, melts at 42-500C and is primarily used in emollient(skin southner) in ointments and cosmetics. Also used in laundry wax for lustering linen, making soap and candles.  All lipids are hydrophobic and mostly insoluble in blood, so they require transport within hydrophilic spherical structures called lipoproteins.
  5. 5. Fats And Oils o Fats and oils are lipids which are saponifiable(having ester functional group)(i.e.complex lipids), while other such steroids are non-saponifiable. o Natural fats and oils are triesters of glycerol with long chain carboxylic acids (12 to 20 carbons). o They are known as Triglycerides. C H2 C H C H2 OH OH OH + C R O O H C R O O H C R O O H C H2 C H C H2 O O O C C C R R R O O O + 3H2O GLYCEROL CARBOXYLIC ACID A TRIGLYCERIDE
  6. 6. Fats And Oils o Ester: The chemical linkage that holds an alcohol group (OH) and an acid group (such as COOH) together. An ester bond is the connection between a fatty acid and glycerol in glycerides. o Glycerol: A three carbon chain, with each carbon containing an alcohol group. One, two or three fatty acids , may be attached to glycerol to give a mono, di or triglyceride. o Triglyceride: Three fatty acids attached to a glycerol molecule. If the three fatty acids are the same, it is a simple triglyceride, if they are different from each other, it is a mixed triglyceride.
  7. 7. Fats And Oils o When three OH groups of glycerol are esterified with the same acid, the triester is known as simple glyceride, where as if two or more different acids called as mixed glyceride. C H2 C H C H2 O O O C C C (CH2)14 CH3 (CH2)14 CH3 (CH2)14 CH3 O O O GLYCERYL TRIPALMITATE (a smiple glyceride) C H2 C H C H2 O O O C C C (CH2)14 CH3 (CH2)16 CH3 (CH2)7CH=CH=CH(CH 2)7CH3 O O O GLYCERYL PALMITOSTEAROOLEATE (a mixed glyceride)
  8. 8. Differences Fats Oils  1. Remains solid at room temperature. (due to large % of saturated fatty acid)  2.Relatively more saturated  3. High melting point.(above 200C)  4. More stable.  5. Source: Mainly animals.  6. No double bonds.  7. Vander waal’s forces between molecules are stronger.  1. Remains liquid at room temperature. (due to large % of unsaturated fatty acid)  2.Relatively more unsaturated  3. Low melting point. (below 200C)  4. Less stable.  5. Source: Mainly Plants.  6. Have double bonds.  7. Vander waal’s forces between molecules are weaker.
  9. 9. Occurrence and extraction  Plants : Plants are store large quantities of fats in their seeds, roots and fruits. Castor beans, peanuts, coconuts and olives have a high fat content.  In animals: in animals, the fat deposits are to be found mostly under the skin and around the intestine and kidneys.  Extraction:  1. Rendering: The animal tissues containing the fat are chopped off and heated dry or with water until the fat melts and can be removed.  2. Pressing: oil are obtained from seeds by crushing between steel rollers and then pressed in a hydraulic press.  3. Solvent extraction: It is applied to the residue after pressing and rendering for complete removal of oil or fat. Solvents used are petroleum ether and benzene.
  10. 10. Physical and Chemical properties  Fats and oils are solid or liquid having a greasy feel, but when pure it is colorless, odorless and tasteless.  They are insoluble in water but soluble in organic solvents like ether, chloroform, benzene, etc.  They have a lower specific gravity than water and consequently float on surface when mixed with each other.  They form emulsion when agitated with water in presence of soap or gelatin.
  11. 11. Physical and Chemical properties Fat and oils are triesters of glycerol with saturated and unsaturated fatty acids. Their reactions are those of ester group in triplicate and carbon-carbon double bonds. 1. Hydrolysis 2. Hydrogenation. 3. Hydrogenolysis 4. Rancidification 5. Drying
  12. 12. Physical and Chemical properties 1. Hydrolysis: They are hydrolysed by heating with acids or alkalies or superheated steam. When boiled with sodium or potassium hydroxide solution, the products are sodium or potassium salts. They latter are called as soap and alkaline hydrolysis are called as saponification. C H2 C H C H2 O O O C C C R R' R'' O O O + 3NaOH A TRIGLYCERIDE C H2 C H C H2 OH OH OH + C R O Na+-O C R O Na + O - C R O Na + O - GLYCEROL Soap
  13. 13. Physical and Chemical properties 2. Hydrogenation: Vegetable oils are triglycerides of unsaturated fatty acids such as oleic acid and linolec acid. On catalytic hydrogenation at low pressure, hydrogen adds across the carbon-carbon double bond of the acid components of the triglycerides, which results in formation of saturated triglycerides. This process is called as Hardening GLYCERYL TRIOLEATE OH2C C(CH2)7CH=CH(CH 2)CH3 O C H C(CH2)7CH=CH(CH 2)CH3 O CH2OC(CH2)7CH=CH(CH 2)CH3 O +3H2 Heat OH2C C(CH2)16CH 3 O C H C(CH2)16CH 3 O CH2OC(CH2)16CH 3 O Glyceryl triestearate (solid fat) M.P - 17 0 LIQUID FAT M.P.- 55 0 c
  14. 14. Physical and Chemical properties 3. Hydrogenolysis: Vlike a ester, the ester group of triglycerides (fats and oils) can be reduced with hydrogen in the presence of copper chromite catalyst, CuCr2O4, at high temperature. This reaction called hydrogenolysis(hydrogenation involving cleavage) gives in addition glycerol and long chain primary alcohol. GLYCERYL TRIOLAURATE C H3 C H3 C H3 (CH2)10 C O O CH2 (CH2)10 C O O CH (CH2)10 C O O CH2 +6H2 Heat 3CH3(CH2)10 CH2OH CuCr2O4 + C H2 C H CH2 OH OH OH LARURYL ALCOHOL GLYCEROL
  15. 15. Physical and Chemical properties 4. Rancidification: When fats and oils are left exposed to moist air, they develop foul smell and sour taste. They are said to have become rancid. Rancidification is caused by two types of reactions: A. Oxidation: it occurs due to the oxidation of carbon- carbon double bonds in fats and oils to produce volatile carboxylic acids. B. Hydrolysis: it involves the hydrolysis of one or more ester linkage in fats and oils to produce the original acid. Bacteria from the air furnish enzymes to promote such reactions. So antioxidants are added to many edible oil to prevent rancidification.
  16. 16. Physical and Chemical properties 5. Drying: When highly unsaturated fats and oils are exposed to air, they undergo oxidation and polymerization to form a thin waterproof film, such oils are called as Drying Oils and the reaction is referred as drying. Linseed oil, which is rich in linolenic acid is a common drying oil used in oil-based paints. Non-drying are the either saturated or only moderately unsaturated.
  17. 17. Saponification Value  Saponification value is also called as saponification number.  It determines the approximate molecular weight of a fat or oil.  Def: Saponification number is defined as the number of miligrams of KOH required to saponify one gram of fat or oil.  In saponification one mole of fat or oil react with three moles of KOH since the former has ester groups.  If M be the molecular weight of fat, M grams of it require 3*56=168 grams or 168,000 miligrams of KOH for saponification.  Saponification number of fat= 168000/M
  18. 18. Saponification Value  As per expression the saponification value of a fat is inversely proportional to the molecular weight.  A lower value of sap, therefore shows the preponderance of high molecular weight fatty acid residues.  On other hand high value of sap indicates preponderance of low molecular weight of fatty acids.

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