Rancidity: When the food materials prepared in fats and oils are kept for a long time, they start giving unpleasant smell and taste, this is called rancidity.
This happens as follows : When the fats and oils present in food materials get oxidised by the oxygen (of air), their oxidation products have unpleasant smell and taste.The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called rancidity
