Ascorbic acid (vitamin C) is used extensively in the food industry, not only for its nutritional value but for its many functional contributi
ons to product quality. Vitamin C has a dual role: it acts as a nutrient as well as a food antioxidant and product improver. It is used as an antioxidant, reducing agent, acidifier, buffering agent, solvent, etc in various food and drinks. It is probably the most important chemical property of vitamin C which protects and improves qualities of fruits, vegetables, meats and poultry, fish and seafoods, milk, cereal grain flours, snack foods, fats, oil, juices and beverages, etc in either fresh, frozen or heat- treated forms.

Functions:

Meat products: Ascorbic acid is widely used in the meat industry for its antioxidant properties. In cured meats, ascorbic acid can: (1) accelerate color development, (2) inhibit nitrosamine formation, (3) prevent oxidation, and (4) prevent color fading. Ascorbic acid is also used in fresh meat to prevent oxidation and color fading during storage. Ascorbic acid can prevent nitrosamine formation in cured meats by reducing nitrate to nitrogen oxide, which will not be able to react with the amines to form nitrosamines.

Bakery products: In dough systems adding ascorbic acid to the flour improves both bred texture and loaf volume. The ascorbic acid is first oxidized to dehydroascorbic acid. Then the reduction of dehydroascorbic acid back to ascorbic acid drives the reaction of sulfhydryl compounds in the gluten to form intermolecular disulfide bonds.

Oils and Fats: The unsaturated long-chain fatty acids present in fats and oils readily oxidize when exposed to heat, light, and air. As in meats, lower molecular weight compounds are formed and impart rancid odors and flavors. Because ascorbic acid is a water soluble compound, it can control these reactions only to a certain extent. The antioxidant effects of ascorbic acid are more apparent in an oil system if ascorbic acid is used in combination with other antioxidants such as tocopherols, BHT, and BHA.

Beverages: Ascorbic acid addition is common in the manufacture of beverages, especially those made from fruit juices. In the manufacture of fruit juices or purees from fruits such as apples and peaches, ascorbic acid may be added during the crushing, straining, or pressing processes to prevent enzymatic browning of the raw fruits. Browning takes place when enzymes called polyphenolases, which occur naturally in fruit tissue. Ascorbic acid can inhibit browning reactions by reducing the quinones back to the original phenol compounds. Also, because polyphenolases are most active in a pH range between 6.0 and 7.0, combinations of ascorbic acid and citric or malic acids are sometimes used to diminish enzyme activity by lowering the pH of the juice or fruit puree. Heat treatment or pasteurization during processing will also inactivate the enzymes and prevent any further enzymatic browning in the final juice products.Ascorbic acid