Page 48 - Natural Antioxidants, Applications in Foods of Animal Origin

Mechanism of Oxidation in Foods of Animal Origin 27
VetBooks.ir with another lipid hydroperoxide to form a peroxyl radical and regenerate

hemin:

hemin(3+) + LOOH LO + hemin(4+)-OH
•

hemin(4+)-OH + LOOH LOO + hemin(3+) + H O
•
2
Alkoxyl and peroxyl radicals are capable of abstracting a hydrogen atom
from a PUFA which will stimulate the lipid oxidation processes (Grunwald
& Richards, 2006b).
Recently, a new heme protein determination method for fish muscle
overcoming such extractability problems faced by previous reported
methods was developed by Chaijan and Undeland (2015). The principle was
to homogenize and heat samples in an SDS-containing phosphate buffer to
dissolve major muscle components and convert ferrous/ferric heme proteins
to hemichromes with a unique absorption peak at 535 nm.

1.7 INTERACTION BETWEEN LIPID OXIDATION PRODUCTS AND
MYOGLOBIN

Lipid oxidation generates a wide range of secondary aldehyde products,
which are predominantly n-alkanals, trans-2-alkenals, 4-hydroxy-trans-
2-alkenals, and malondialdehyde (Lynch & Faustman, 2000). Lynch et al.
(2001) demonstrated that propional, pentenal, hexanal, and 4-hydroxynon-
enal (4-HNE) were the primary aldehydes formed during lipid oxidation
in stored ground beef at 4 °C. The aldehyde products are more stable than
free radical species and readily diffuse into the cellular media, where they
may exert toxicological effects by reacting with critical biomolecules in vivo
(Esterbauer et al., 1991). Aldehydes produced during lipid oxidation can
form adducts with proteins and this may have an impact on protein stability
and functionality as well as the color stability of meat. Aldehyde products
can alter myoglobin stability (Lynch & Faustman, 2000). Covalent modi-
fication of equine, bovine, porcine and tuna myoglobin by 4-hydroxynon-
enal (4-HNE) has been demonstrated (Faustman et al., 1999; Phillips et al.,
2001a, 2001b; Lee et al., 2003a, 2003b). Lynch and Faustman (2000) also
determined the effect of aldehydic lipid oxidation products on oxymyo-
globin oxidation, metmyoglobin reduction and the catalytic activity of
metmyoglobin as a lipid prooxidant in vitro. Metmyoglobin formation was
greater in the presence of α,β-unsaturated aldehydes than their saturated