Rancidity of vegetable oils is a major problem in food related industries. It occurs during storage and is caused by oxidation of unsaturated fatty acids, resulting in foul odors and tastes in the product. Oxidative stability is affected by a number of factors including oxygen, temperature, presence of metals and light. The resistance of edible oil to oxidation is enhanced by endogenous or added antioxidants. Although oxidation is inevitable over time, it can be minimized by optimizing processing methods and storage conditions for maximum shelf life.