Chemistry Reference
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Fig. 12.1 The lipid oxidation mechanism.
via chemistry akin to the Fenton reaction. The alkoxyl and hydroxyl radicals
produced in this way can continue the propagation phase of the reaction by
abstracting a hydrogen from a lipid and forming another carbon-centered
radical. Hydroperoxides also undergo a variety of decomposition reactions
generating compounds that result in off, rancid or stale aromas. The oxidation
process ends as substrates become depleted and radical recombination reactions
begin to dominate. Non-lipid food constituents can also undergo oxidative
changes. Pigment degradation, oxidative vitamin loss and protein oxidation are
just a few examples.
12.3.3 How antioxidants work
Antioxidants function in different ways, depending upon which part of the lipid
oxidation pathway they interfere with. Antioxidants are commonly classified as
primary antioxidants, secondary antioxidants, chelators, quenchers, oxygen
scavengers, and antioxidant regenerators. The role of these antioxidants in
interfering with various stages of the antioxidant mechanism is shown in Fig.
12.2. Some antioxidants function in more than one of these categories.
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