Page 23 - Natural Antioxidants, Applications in Foods of Animal Origin

2 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir ABSTRACT

Lipid and myoglobin oxidations significantly impair the quality of foods of
animal origin because these reactions deteriorate flavor and color, induce the
loss of nutritional value and cause technological problems during processing.
Lipid and myoglobin oxidations are coupled and such reactions can occur
via non-enzymatic and enzymatic routes. Several factors have been reported
to enhance the oxidation of lipid in muscle foods including species, muscle
type, fatty acid composition, endogenous antioxidants (AH), temperature,
metal ions, sodium chloride, muscle pH, and processing parameters. It is most
likely that the prooxidant effect of heme proteins, especially myoglobin, is
a prime factor influencing the lipid oxidation in muscle foods. On the other
hand, lipid oxidation results in a wide range of aldehyde products, which
can cause the oxidation of myoglobin. The interaction between myoglobin
and aldehydic lipid oxidation products can alter myoglobin redox stability
and finally results in muscle discoloration. As a consequence, the oxidation
of both lipid and myoglobin directly affect the quality and acceptability of
muscle foods and those reactions seems to promote each other.

1.1 INTRODUCTION

The problems associated with oxidation in foods of animal origin, partic-
ularly meat and muscle foods, have gained much interest as they relate to
flavor deterioration, discoloration, loss of nutritional value and safety, biolog-
ical damage, ageing, and functional property changes. Meat and other muscle
foods are complex foods with highly structured nutritional compositions
(Rodriguez-Estrada et al., 1997). Muscles are composed of water, proteins,
lipids, carbohydrates, vitamins, and minerals in variable amounts depending
on several factors such as breeds, muscle types, dietary, and growth perfor-
mance (Wattanachant et al., 2005). Oxidation is a major cause of quality dete-
rioration for a variety of raw and processed muscle foods during handling,
processing, and storage. Lipid, protein, pigment, and vitamin in muscle tissue
are susceptible to oxidative reactions. These changes resulted from reactions
of active oxygen species, free radicals, enzymes, and prooxidants with unsat-
urated fatty acids in lipids, amino acids in proteins, heme groups in pigments
and the chains in vitamins with conjugated double bonds. However, lipid
oxidation and the oxidation of heme proteins, particularly myoglobin, in
muscle foods are major deteriorative reactions which occur in a concurrent
manner and each process appears to enhance the other. During oxidation of