Page 38 - Natural Antioxidants, Applications in Foods of Animal Origin
P. 38
Mechanism of Oxidation in Foods of Animal Origin 17
VetBooks.ir 1.4.7 PARTICLE SIZE REDUCTION AND TUMBLING
Ladikos and Lougovois (1990) postulated that any process causing disruption
of the muscle membrane system, such as grinding, cooking, and deboning,
results in exposure of the labile lipid components to oxygen, and thus accel-
erate development of oxidative rancidity. Destruction of the extremely well
organized structure of living animal cells will bring together lipids, oxidation
catalysts, and enzymes responsible for lipid oxidation. Pearson et al. (1977)
suggested that chopping and emulsification are at least as likely to cause
WOF as grinding or mincing of samples. Dawson and Gartner (1983) attrib-
uted the high oxidative potential of mechanically deboned poultry to the
extreme stress and aeration during the process and the compositional nature
(bone marrow, heme, and lipids) of the product; TBA values increase most
rapidly with decreasing particle sizes, as the latter are related to greater cell
disruption. On the other hand, comminuted beef has a storage life similar to
that of intact pork, despite the differences in fatty acid composition (Enser,
1987).
The mechanical force of tumbling can break the structure of the cell and
organelle membranes which could lead to an exposure of phospholipids
to cellular prooxidants (e.g., iron and heme proteins) or free radicals. The
tumbling process has also been found to promote lipid oxidation in beef
bottom round (Cheng & Ockerman, 2003). However, inhibition of lipid
oxidation by the citric acid marination could be due the removal of prooxi-
dants such as heme proteins by the marination/tumbling procedure. Alter-
nately, inhibition of lipid oxidation could be due to the presence of citric acid
since these molecules are strong metal chelators (Ke et al., 2009).
1.4.8 HIGH PRESSURE PROCESSING
High pressure (HP) processing has been shown to initiate lipid oxidation in
fresh meat, especially a threshold pressure around 500 MPa seems to exist,
which can lead to reduced quality and shelf life (Bolumar et al., 2014). Two
mechanisms have been proposed to explain the pressure-induced lipid oxida-
tion: (a) increased accessibility of iron from hemoproteins and (b) membrane
disruption. Several studies have observed that the addition of ethylenediami-
netetraacetic acid (EDTA), which can chelate metal ions like iron, can be
correlated with a reduction of the lipid oxidation in meat processed by HP,
which suggests that transition metal ion catalysis is the major factor under-
lying the increased lipid oxidation (Beltran et al., 2004; Ma et al., 2007).