lipids fixed oils and waxes PH103.9

Recap In the last class you learnt about Alkaloids Tests for alkaloids Types of alkaloids PH103.9

On completion of this period, you would be able to know Objectives On completion of this period, you would be able to know Lipids Fixed Oils Fats waxes PH103.9

Fixed Oils, Fats & Waxes These can be obtained from plants or animals Fixed oils are liquids at normal temperature Fats are solids or semisolids Chemically fixed oils and fats are esters of fatty acids with glycerol known as glycerides PH103.9

Fixed Oils, Fats & Waxes Fats usually contain mixed glycerides Usually contain saturated fatty acids like Stearic acid, Palmitic acid, Unsaturated fatty acids like Oleic acid, Linoleic acid The oils of have more amount of Unsaturated acids where as fats comprise of Larger amount of saturated fatty acids PH103.9

Fixed Oils, Fats & Waxes Fixed oils and fats can be easily hydrolysed with aqueous sodium hydroxide On hydrolysis we get sodium salts of fatty acids (Soap) and glycerol, this process is known as Saponification They are insoluble in water Sparingly soluble in cold alcohol Soluble in Benzene, Chloroform and Ether PH103.9

Fixed Oils, Fats & Waxes Fixed oils and fats cannot be distilled If try to do as they get decomposed Due to production of acrolein an aldehyde If stored for longer period Fixed oils and fats become rancid by having bad taste and unpleasant odour PH103.9

Fixed oils Classified into Drying oils Linseed oil Semi drying oils Cotton seed oil Non drying oils Olive oil PH103.9

Fats Cocoa Butter Cocoa beans Lanolin or Hydrous Wool fat Sheep PH103.9

Fatty acids Structural formula Butyric acid CH3 [CH2]2 COOH Caproic Acid CH3 [CH2]4 COOH Caprilic Acid CH3 [CH2]6 COOH Capric Acid CH3 [CH2]8 COOH PH103.9

Fatty acids Structural formula Lauric Acid CH3 [CH2]10 COOH Myristic Acid CH3 [CH2]12 COOH Palmitic Acid CH3 [CH2]14 COOH Stearic Acid CH3 [CH2]16 COOH Arachidic Acid CH3 [CH2]18 COOH PH103.9

Waxes The physical properties of waxes are almost similar to fats They too are esters like oils and fats But in waxes alcohol involved is not glycerol But a high molecular weight straight chain monohydroxy alcohol like cetyl alcohol PH103.9

Waxes Fatty acids are also high molecular weight saturated fatty acids Waxes can be saponified only with alcoholic potassium hydroxide Like fats they are insoluble in water Soluble in organic solvents Ex. Bees wax and spermaceti PH103.9

Adulteration in oils Fats and Waxes To ascertain its purity physical or chemical test are to be carried by comparing with analytical constants PH103.9

Adulteration in oils Fats and Waxes Saponification value This value is normally applied for butterfat and denotes total amount of fatty acids present Iodine value Iodine value is a measure of the extent of unsaturation Acid value Denotes amount of free fatty acids present PH103.9

Summary In this class we learnt about Lipids Fixed Oils Fats Waxes PH103.9

Quiz 1. Acid value is the measure of Rancidity Peroxidation Unsaturation All the above PH103.9

Quiz 2.Iodine value is the measure of Peroxidation Hydrogenation Unsaturation None of the above PH103.9

Frequently Asked Questions What are the classes of oils or lipids? What are fixed oils? Give examples and sources of them? PH103.9