Vitamins as antioxidants in processed foods

Vitamins as antioxidants in processed foods
Oxidation, a series of chemical reactions yielding undesirable and products (off odors, colors, and flavors), may occur in many fruits and vegetables and foods high in fat and oil during exposure to air, light, heat, heavy metals, certain pigments or alkaline conditions. Enzymatic browning may occur in some fruits and vegetables, particularly apples, banana, peaches, pear, and potatoes, which contain phenolase enzymes. When these fruits and vegetables are cut or sliced and exposed to air, the phenolases catalyze oxidation of phenolics compounds to ortho-quinone compounds, which then polymerize, forming brown pigments.

Oxidation in lipids (autoxidation) and in fat and oil containing foods, on the other hand, occurs as a result of the susceptibility of fatty acids (building blocks of fats and oils) to oxidations and subsequent formation of reactive compounds referred to as “free radicals”.

The free radicals promote the development of a series of chemical reactions which lead to the production of off-flavors, colors, odors, and rancidity. While both saturated and unsaturated fatty acids are susceptible to oxidation, unsaturated fatty acids are significantly more susceptible than their saturated counterparts at room temperatures and at elevated temperatures.

Antioxidants, as defined by Food and Drug Administration are “substances used to preserve food by retarding deterioration, rancidity or discoloration due to oxidation.” Some oxidations have more than one function. For example, Ascorbic acids may function as a free-radical chain terminator, and oxygen scavenger, or a metal chelator. Under certain conditions, it may act as a promoter for oxidation.
Vitamins as antioxidants in processed foods

Additive and Packaging

Additive and Packaging
A few additives, such as bleaching agents used in flour, can promote oxidation and lead to small losses of sensitive vitamins. However, other food additives, particularly the antioxidants, have protective effects on vitamins. The common antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and alpha-tocopherol (vitamin E), protect vitamins A and D and beta-carotene and slow oxidative destruction of fats. Vitamin C can stabilize vitamins A and E, thiamin, and folic acid by inhibiting oxidative reaction promoted by iron and copper.

In addition to the benefits of using antioxidants, a number of other techniques are utilized to protect the nutritive quality of our foods. These techniques include use of sequestering agents (compounds which binds to minerals and prevent them from enhancing oxidation), control of moisture content, application of protective gelatin coatings to vitamins prior to addition to foods, use of aerosol supercoatings on products such as breakfast cereal, and use packaging to protect the food from the atmosphere and light.
Additive and Packaging