Acid number of fats-

Naturally occurring oils and fats are the esters of higher fatty acids with the trihydric alcohol glycerol and are enormously found in nature.
Chemically, fats are identical with oils in all respect except that the fats are solid at room temperature whereas oils are liquid.
Fat is the reserve food material in human body. It acts as insulator for the loss of body heat and also serves as a padding material for protecting internal organs.
Physical properties of fats-
Fats are insolublein water and soluble in organic solvent such as ether, chloroform, benzene. Melting point is low and pure fats have no colour, odour or taste. The specific gravity of solid fat is about 0.86.
Chemical properties-
1)Hydrolysis-
Hydrolysis of fats takes place by lipase producing fatty acids and glycerol. Phosholipase attack the ester linkages of phosholipids.
2) Saponification-
Hydrolysis of fatby alkali is called saponification. The products are glycerol and the alkali salts of fatty acids which are called soaps.
3)Halogenation-
Fats react with halogens to give addition product.
4)Rancidity-
Nearly all natural fats are oxidized when expose to air, light, moisture, particularly if warm, developing an unpleasant odour and taste. This happens due to the formation of peroxides at the double bond of unsaturated fatty acids. Vitamin E is an important natural antioxidant.