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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 2 Structures of some synthetic antioxidants.<br />

animal fats, but ineffective for vegetable fats. BHA has good carry-through in baking<br />

but volatilizes during frying. It is commonly added to packaging materials.<br />

2. Butylated Hydroxytoluene<br />

BHT is a widely used monophenolic antioxidant. This fat-soluble white, crystalline<br />

solid is appropriate for high temperature processing but is not as stable as BHA. It<br />

will volatilize <strong>and</strong> has less carry-through. BHA <strong>and</strong> BHT act synergistically to provide<br />

greater antioxidant activity than either antioxidant alone. Therefore, foods typically<br />

contain BHA/BHT mixtures at levels up to 0.02%. The postulated synergistic<br />

mechanism of BHA <strong>and</strong> BHT involves the interactions of BHA with peroxy radicals<br />

to produce a BHA phenoxy radical. The BHA phenoxy radical is then believed to<br />

abstract a hydrogen from the hydroxyl group of BHT. BHT effectively acts as a<br />

hydrogen replenisher of BHA, allowing BHA to regenerate its effectiveness. The<br />

BHT radical can then react with a peroxy radical <strong>and</strong> act as a chain terminator [7].<br />

3. Tertiary Butylhydroxyquinone<br />

TBHQ is a beige diphenolic powder. It is used in frying applications with highly<br />

unsaturated vegetable oils, where it has good carry-through. It is generally considered<br />

to be more effective in vegetable oils than BHA or BHT [5]. Citric acid <strong>and</strong> TBHQ<br />

show excellent synergism in vegetable oils. TBHQ is not permitted for use in foods<br />

in Canada or the European Economic Community. In the United States, TBHQ is<br />

not permitted to be combined with PG.<br />

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

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