Rancidity is the process of slow oxidation of fats and oil present in the food materials resulting in the production of foul odour and taste in them. Method to prevent rancidity. 1.packing of food material in air tight container . 2. Refrigeration of cooked food at low temperature. 3. By adding antioxidant e.g:- bha and bht 4. Avoiding the food material and cooked food keeping in direct sunlight.