chapter  15
Antioxidants
Pages 26

I. Introduction .......................................................................................................................... 409 II. Antioxidants ......................................................................................................................... 410

A. Classification................................................................................................................ 410 1. Primary Antioxidants............................................................................................ 410 2. Secondary Antioxidants........................................................................................ 412

III. Synthetic and Natural Antioxidants ..................................................................................... 413 A. Synthetic Antioxidants................................................................................................. 414

1. Butylated Hydroxyanisole .................................................................................... 415 2. Butylated Hydroxytoluene.................................................................................... 415 3. Tertiary Butylhydroxyquinone ............................................................................. 415 4. 6-Ethoxy-1,2-Dihydro-2,2,4-Trimethylquinoline (Ethoxyquin)........................... 418 5. Gallates ................................................................................................................. 418 6. Tocopherols .......................................................................................................... 418 7. Erythorbic Acid and Ascorbyl Palmitate.............................................................. 419

B. Natural Antioxidants .................................................................................................... 419 1. Tocopherols and Tocotrienols ............................................................................ 419 2. Ascorbic Acid and Ascorbate Salts .................................................................... 421 3. Carotenoids ......................................................................................................... 422 4. Enzymatic Antioxidants...................................................................................... 423 5. Proteins and Related Substances ........................................................................ 424 6. Maillard Reaction Products ................................................................................ 424 7. Phospholipids...................................................................................................... 425 8. Sterols ................................................................................................................. 425 9. Sulfur Dioxide and Other Sulfites ...................................................................... 425 10. Gums................................................................................................................... 425 11. Antioxidants in Plants ........................................................................................ 426 12. Nutritional Aspects ............................................................................................. 428

References ..................................................................................................................................... 430

Lipid oxidation in foods is a serious problem, difficult to overcome often, and leads to loss of shelf life, palatability, functionality, and nutritional quality. Loss of palatability is due to the generation of off-flavors that arise primarily from the breakdown of unsaturated fatty acids during autoxidation. The high reactivity of the carbon double bonds in unsaturated fatty acids makes these substances primary targets for free radical reactions. Autoxidation is the oxidative deterioration of unsaturated fatty acids via an autocatalytic process consisting of a free radical chain mechanism [1]. The chain

and termination. reactions are primarily responsible for the autocatalytic nature of autoxidation.