What are the reasons antioxidants added to foods?

Antioxidants are food additives used since about 1947, to stabilize foods that by their composition would otherwise undergo significant loss in quality in the presence of oxygen.

The uses of antioxidant have a positive effect relative to nutrition. For example, without added antioxidant, essential unsaturated fatty acids, and certain vitamins can be degraded with processing and storage thereby lowering the overall nutritional value of certain foods.

Vitamin C

Oxidative quality changes in foods inlcdue:
*The development of rancidity from the oxidation of unsaturated fats resulting in off-odors and off-flavors
*Discoloration from oxidation of pigments or other components of the food

Antioxidants play an important role in the deceleration of lipid oxidation reactions in foodstuff. According to FDA they are defined as: substances used as preservatives, with the aim to reduce spoilage, rancidity or food discoloration, which are derived from oxidations.

These are some examples of antioxidant food additives:
*Ascorbic acid
*Butylated hydroxyanisole
*Butylated hydroxytoluene
*Propyl gallate
*Tocopherols
What are the reasons antioxidants added to foods?