Page 170 - Natural Antioxidants, Applications in Foods of Animal Origin

Natural Antioxidants: Control of Oxidation in Fish and Fish Products 149
VetBooks.ir R + O → ROO .

.
2
ROO + RH → R + ROOH
.
.
Termination: This reaction describes the combination of two fatty acid
radicals leading to the formation of non-radical products in the presence
of oxygen. The reactions between peroxyl and alkoxyl radicals take place
under atmospheric conditions while reactions between alkyl and radicals
lead to the formation of fatty acid dimers under low oxygen levels(Abidi &

Rennick, 2003).
2RO → O + RO R
.
2 2 2
RO → RO R
.
2 2

4.4 ANTIOXIDANTS

Antioxidants are regarded as key agents for improving oxidative stability
of fish products and act as preservatives which are added to food items at
various stages of processing (McClain & Bausch, 2003). Antioxidant effec-

tiveness is related to activation energy, oxidation–reduction potential, rate
constants, ease with which the antioxidant is lost or destroyed (volatility and
heat susceptibility), and antioxidant solubility(O’Connor & O’Brien, 2006).

They are compounds that delay auto-oxidation by inhibiting formation of
free radicals by one (or more) of several mechanisms:

1) Scavenging species that initiate peroxidation.
2) Chelating metal ions such that they are unable to decompose lipid
peroxides or generate reactive species.
3) Breaking the auto-oxidative chain reaction, and/or reducing local-
ized O concentrations.
2
4) Quenching O preventing formation of peroxides.
−
2
Antioxidants have been reported to play an important role in the body
by protection against oxidative damage (especially damage to the DNA),
and delay chronic health problems like cataracts (Morton et al., 2000).

Although the Food and Drug Administration (FDA) defines antioxidants
only as dietary supplements to be taken with normal food consumption,
they also serve as preservatives for packaged foods. They are added to