Antioxidants are chemical compounds that provide stability to fats and oils by delaying oxidation (which involves the loss of electrons and the gain of oxygen).
An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent.
Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions.
Antioxidants are widely used in dietary supplements and have been investigated for the prevention of diseases such as cancer, coronary heart disease and even altitude sickness.
The most commonly used antioxidant formulations contain combinationsof BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene),and propyl gallate. These formulations usually contain a chelating agent (reacts with metal to form a complex and thus preventsthe metal from acting as a catalyst in oxidative reactions), of which citric acid is the most common.
Antioxidants are effective at low concentrations, that is, 0.02% or less, based on the fat or oil content of the food.Examples of applications are:
• Rendered animal fat, such as lard
• Vegetable oils, such as cottonseed oil and corn oil
• Food products of high fat content, such as doughnuts and potato chips
• Food products of low fat content, such as cereals and dehydrated potatoes
Read more at Wikipedia