Metals and food oxidation - Oxidation in Foods and Beverages and Antioxidant Applications - page 52

balance between pro-oxidants and antioxidants, and the pro-oxidative effects
greatly increase. In cooked muscle foods, lipid peroxidation propogate mostly
by the following reactions:
Fe 2 LOOH ÿ! Fe 3 LO · HO ÿ
Fe 3 AH 2 ÿ! Fe 2 AH ·
where AH 2 and AH · are ascorbic acid or other reducing agents and the ascorbyl
radical.
2.7.3 Muscle food nutritive value
Partially oxidized food, for example, heated red meat, undergoes further oxida-
tion by metal catalysis under simulated and in vivo stomach conditions yielding
deleterious compounds such as hydroperoxides and reactive carbonyls; for
example, malondialdehyde (MDA), a lipotoxin (Kanner and Lapidot, 2001). The
cross-reaction between free radicals produced during this reaction in stomach
conditions also co-oxidized vitamin E, -carotene and vitamin C (Gorelik et al.,
2008a, 2008b). The lipotoxin MDA level in rat and human plasma increase
significantly following the consumption of red turkey meat (Gorelik et al.,
2008a, 2008b). In human volunteers baseline plasma levels of MDA were
5020 nM and after a meal of turkey meat cutlets, plasma MDA levels in
volunteers increased by 160 nM. The elevation of plasma MDA in rats and
humans was completely prevented by integration of red-wine polyphenols in the
diet (Gorelik et al., 2008a, 2008b). The findings explain the potential harmful
effects of metal catalysis of lipid peroxidation and lipotoxins found in foods,
further lipid peroxidation in stomach medium and the important benefit of
consumption of dietary polyphenols during the meal.
2.8 Future trends
Current research and development studies should emphasize their direction
towards functional, health promoting foods and dietary recommendation for
health maintenance and well-being throughout life. Epidemiological studies and
experimental data suggest that diets high in fat and red meat are risk factors
contributing to the development of atherogenesis and several kinds of cancer.
The Western diet contains large quantities of oxidized fatty acids, oxidized
cholesterol and cytotoxic carbonyls because a large proportion of the food in the
diet is often consumed in a fried, heated or processed form.
Consumption of partially oxidized food enhanced lipid peroxidation in the
stomach and consequent production and absorption of cytotoxic lipid
peroxidation end products into the plasma. Repeated consumption of oxidized
fat in the diet poses a chronic threat to human health. In order to prevent the risk
factors from oxidized foods on human health, action should be considered `from
the farm to the fork' and more.