Food Lipids: Chemistry, Nutrition, and Biotechnology

and its extent was related to intensity and duration of the treatment [322]. Inhibition
of lipid oxidation by the addition of ethylenediaminetetraacetic acid (EDTA) to pressure-treated
minced pork indicated that transition metal ions were probably released
from complexes and became available to catalyze oxidation in the treated samples
[323].
K. Drying
Drying has been a process applied to muscle foods for hundreds of years to extend
the product’s shelf life through reduction in water and subsequent inhibition of microbial
growth. Freeze drying is an extension of this process; however, the porosity
and surface areas of its products are higher than those of traditional dried products
and therefore oxidation of freeze-dried products occurs more readily [324]. However,
reduced surface areas of products subjected to controlled low temperature vacuum
dehydration minimized the increased lipid oxidation associated with freeze-dried
products [325].
L. Irradiation
Irradiation is the process of subjecting materials to electromagnetic radiation or electron
beams of sufficient energy levels to sever chemical bonds. While application of
irradiation to muscle foods is intended to control pathogenic microorganisms, undesirable
sensory changes in foods, especially development of off-flavors, may also
arise, especially as the dose of radiation increases. For example, both Heath et al.
[326] and Hashim et al. [327] reported that irradiation of uncooked chicken breast
and thigh produced a characteristic bloody and sweet aroma that remained after the
thighs were cooked but was not detectable after the breasts were cooked. These offflavors
are distinct from those associated with lipid oxidation and are believed to
arise from protein oxidation. To support this statement, aldehydes, ketones, and alcohols,
typical volatile classes associated with lipid oxidation, did not increase following
irradiation of pork loin and pork sausage [328,329], whereas irradiation
increased the production of sulfur-containing volatiles (carbon disulfide, mercaptomethane,
dimethyl sulfide, methyl thioacetate, and dimethyl disulfide) in pork loin
[329]. The majority of these sulfur-containing volatiles dissipate from aerobically
packaged samples whereas oxidative volatiles increase [329]. Acceleration in lipid
oxidation of stored irradiated samples may be circumvented by storage in vacuum
packaging [328,330,331] or by antioxidant addition/supplementation to muscles
[328,332,333].
M. Glazing
Glazing is a popular technique applied to fish products that will be frozen. Many
types of glazes have been used, but the main glaze of commercial importance is a
layer of ice, usually applied by immersing the product in water or by spraying it
with water. The ice layer that is formed retards dehydration by preventing moisture
from leaving the product and delays oxidation by preventing air contact with the
product. However, as storage time progresses, sublimation occurs, thus decreasing
effectiveness of such glazes as inhibitors. Various chemicals, including disodium acid
phosphate, sodium carbonate, sodium lactate, corn syrup solids, cellulose gums, and
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