Page 118 - Natural Antioxidants, Applications in Foods of Animal Origin

Potential Applications of Natural Antioxidants in Meat and Meat Products 97
VetBooks.ir natural antioxidants (present in plant materials and other natural sources).

Several endogenous antioxidants (including ubiquinone, glutathione, lipoic
acid, spermine, carnosine, and anserine) have been studied in skeletal
muscle (Decker et al., 2000). Both carnosine and anserine are histidyl dipep-
tides and the most abundant antioxidants in meat. Carnosine is present at
around 365 mg/100 g in beef (Purchas & Busboom, 2005) and 400 mg/100 g
in lamb (Purchas et al., 2004). Anserine is especially abundant in chicken
muscle. The antioxidant activity of these dipeptides may result from their
ability to chelate transition metals (Brown, 1981) and form complexes with
copper, zinc, and cobalt. Levels of Coenzyme Q10 (ubiquinone) in meat has
been estimated to be around 2 mg/100 g in both beef and mutton (Purchas
& Busboom, 2005). Glutathione, a component of glutathione peroxidase
enzymes, has an important antioxidant function. Glutathione levels in red
meat are estimated to be 12–26 mg/100 g in beef (Jones et al., 1992). In addi-
tion, numerous Maillard reaction products formed during cooking have also
been shown to have antioxidant activities (Bailey, 1988). However, none
of these antioxidant systems, individually or combined, have been shown
to sufficiently delay oxidation in meat or meat products under common
processing conditions (Decker & Mei, 1996). Therefore, the best strategy
to combat this problem is either supplementation of exogenous antioxidants
through dietary manipulation or incorporation during processing of products.
This chapter will deal with sources of natural antioxidants such as fruits,
vegetables, herbs, and spices as well as marine macroalgae, their application
in meat and meat products and effects on various quality and acceptability.

3.2 ANTIOXIDANTS: MECHANISM OF ACTION

Antioxidants are substances that at low concentrations retard the oxidation
of easily oxidizable biomolecules, such as lipids and proteins in meat prod-
ucts, thus improving shelf life of products by protecting them against dete-
rioration caused by oxidation (Karre et al., 2013).
According to their mechanism of action, antioxidants can be classified
into different groups:

• Antioxidants that act as radical scavengers (react with free radicals):
Two basic mechanisms are involved in this free radical scavenging
activity of antioxidants: (a) A chain breaking mechanism in which the
antioxidants break the chain reaction of radicals and avoid the propa-
gation step of lipid peroxidation process by donating electrons to the