| Radical scavengers |
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The term antioxidant is most often used to refer to radical scavengers, which prolong shelf life by preventing lipid oxidation. Radical scavengers – usually phenolic-type compounds – stop the formation of free radicals by acting as hydrogen donors. The radical scavengers themselves remain fairly stable and are incapable of initiating or propagating further lipid oxidation. The molecular structure of a phenolic-type compound contains an aromatic ring, capable of taking up an unpaired electron (which causes the formation of free radicals). The radical scavenger does not become an active radical itself and the lipid oxidation reaction is terminated. Many different radical scavengers are available, both synthetic and natural. Their efficacy can differ, depending on the complete molecular structure, not just the aromatic ring. Radical scavengers can prolong shelf life, but they cannot prevent oxidation indefinitely. Once a scavenger molecule has trapped a radical, its job is done. It cannot trap another. When they are all used, lipid oxidation can occur very rapidly. |
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