Page 41 - Natural Antioxidants, Applications in Foods of Animal Origin

20 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir formation of metmyoglobin, the changes in tryptophan fluorescence inten-

sity as well as the disappearance of Soret absorption. Furthermore, the rate
of myoglobin autoxidation was related to oxygen concentration (Brown
& Mebine, 1969). Atmospheres enriched in carbon dioxide (CO ) are effec-
2
tive in delaying spoilage of meat; however, one problem is that CO can
2
promote the oxidation of oxymyoglobin to metmyoglobin, thereby causing
the discoloration (Haard, 1992). Post-harvest discoloration of fish muscle
has been reviewed by Chaijan and Panpipat (2009).
It has been suggested that myoglobin has a close relationship with
lipid oxidation (O’Grady et al., 2001; Ohshima et al., 1988). Besides the
unpleasant color, the oxidation of myoglobin is the main cause in the devel-
opment of the undesirable odor during ice storage of fish muscle. Lee et al.
(2003a) reported that surface metmyoglobin accumulation and lipid oxida-
tion of refrigerated tuna (Thunnus albacares) steaks increased during six
days of storage, leading to discoloration and lowered odor acceptability.
The total lipid hydroperoxide content and TBARS of the yellowtail (Seriola
quinqueradiata) dark muscle were higher than those of the ordinary muscle
during two days of ice storage. Those changes were accompanied with the
increasing intensity of fishy, spoiled, and rancid off-odor smells as well as
increasing metmyoglobin formation. However, no correlation was found
between the content of total lipid hydroperoxide and the odor intensities
in ordinary muscle (Sohn et al., 2005). It is believed that the formation of
metmyoglobin by the oxidation of myoglobin predominantly in dark muscle
accelerates lipid oxidation and leads to the generation of greater amounts
of hydroperoxide. Thus, the lipid oxidation associated with metmyoglobin
formation may have caused the development of the rancid off-odor and fishy
smell in dark muscle. For ordinary muscle of yellowtail which contained
a low level of metmyoglobin, the influence of myoglobin oxidation on the
development of rancid off-odor appeared to be insignificant (Sohn et al.,
2005). The suppression of myoglobin oxidation will in turn decrease lipid
oxidation and off-odor development of muscle foods.

1.6 INTERRELATIONSHIP BETWEEN LIPID OXIDATION AND
MYOGLOBIN OXIDATION IN FOODS OF ANIMAL ORIGIN

The heme proteins including hemoglobin and myoglobin are effective
promoters of lipid oxidation (Love, 1983; Han et al., 1994). Myoglobin
consists of a globin portion plus a porphyrin heme, the latter containing an
iron atom coordinated inside the heme ring (Grunwald & Richards, 2006a,