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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 8 Products formed from the oxidation of �-carotene by a peroxyl radical. (Adapted<br />

from Ref. 24.)<br />

F. Water-Soluble Free Radial Inactivators<br />

Free radicals are generated in the water phase of foods by processes such as the<br />

Fenton reaction, which produces hydroxyl radicals from hydrogen peroxide [25,26].<br />

Since free radicals are found in the aqueous phase, biological systems contain watersoluble<br />

compounds capable of free radical inactivation. Ascorbic acid <strong>and</strong> glutathione<br />

scavenge free radicals, resulting in the formation of low energy ascorbate <strong>and</strong> glutathione<br />

radicals [3]. While ascorbate <strong>and</strong> glutathione form low energy radicals, other<br />

factors influence whether these compounds will act as antioxidants. Both ascorbate<br />

<strong>and</strong> glutathione are strong reducing compounds. Ascorbate, <strong>and</strong> in some cases glutathione,<br />

will catalyze the reduction of transition metals, which in turn can react with<br />

Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.

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