Page 33 - Natural Antioxidants, Applications in Foods of Animal Origin
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12                 Natural Antioxidants: Applications in Foods of Animal Origin
  VetBooks.ir  E) which is considered as the most important natural AH. Tocopherol can


            donate a hydrogen atom to the radicals L  or LOO  functioning as the mole-
                                                        •
                                                •
            cule AH. It is generally assumed that the resulting tocopheryl radical reacts
            with ascorbic acid (Vitamin C) at the lipid/water  interface, regenerating
            the tocopherol molecule. Muscle-based foods that contain relatively high
            concentrations of α-tocopherol demonstrate greater lipid and oxymyoglobin
            stability (Faustman et al., 1998). Poultry meat is composed of relatively high
            levels of unsaturated fatty acids and low levels of natural tocopherols and
            thus poultry products are very susceptible to the development of off-flavors
            due to oxidative rancidity (Dawson & Gartner, 1983). According to Wilson
            et al. (1976), turkey meat containing lower levels of natural tocopherol is
            most susceptible to warmed-over-flavor (WOF) development, followed
            closely by chicken, then by pork, beef, and mutton. The use of mechanically
            deboned poultry meat enhances the tendency of poultry products to oxidize
            (Moerck & Ball, 1974). However, the use of mechanically deboned beef
            in beef meat products did not result in flavor deterioration during storage,
            compared to control samples made of hand-boned beef, suggesting that lipid
            oxidation is not a problem as with chicken and fish; this was attributed to
            differences in the degree of unsaturation of fatty acids (Allen & Foegeding,
            1981).
               Other compounds, for example the carotenoids and phenols, have been
            known to  function  as AH (Huss, 1995).  Vareltzis  et  al. (2008) reported
            that  adding  fish  press  juice  to  washed  cod  mince  could  inhibit  hemo-
            globin-mediated  lipid  oxidation  of  protein  isolates  obtained  from  cod
            muscle (Gadus morhua). Press juice obtained from chicken breast muscle
            also showed a potent inhibitor of hemoglobin-mediated lipid oxidation in
            washed cod muscle (Li et al., 2005). The aqueous phase of chicken breast
            muscle includes low-molecular-weight (LMW) components such as ascor-
            bate, urate, glutathione,  bilirubin, and histidine-containing dipeptides
            (Chan  et al., 1994). High-molecular-weight (HMW) components include
            glutathione peroxidase, superoxide dismutase, catalase, transferrin, hapto-
            globin, albumin, ceruloplasmin, and hemopexin (Decker, 1998). Erickson
            et al. (1990) reported that both the LMW (<10 kDa) and HMW (>6–8 kDa)
            cytosol fractions from flounder tissue inhibited iron-mediated lipid oxida-
            tion in flounder sarcoplasmic reticulum and the effect was believed to be
            due to the binding of iron. Furthermore, Slabyj and Hultin (1984) reported
            that both LMW and HMW components in herring cytosol could inhibit iron-
            mediated lipid oxidation in microsomes. Han and Liston (1989) reported the
            ability of rainbow trout cytosol to inhibit iron-mediated lipid oxidation in
            fish muscle microsomes.
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