Page 296 - Natural Antioxidants, Applications in Foods of Animal Origin

Application of Natural Antioxidants in Dairy Foods 275
VetBooks.ir Antioxidants are naturally present in a wide variety of raw food mate-

rials; still there is a need to add antioxidants into foods so as to provide
additional protection against oxidation. The antioxidants which are added
to food products can be natural or synthetic compounds depending on their
availability and preparations (Yanishlieva-Maslarova, 2001). Natural anti-
oxidants such as polyphenols are primarily derived from plants, while the
synthetic antioxidants are chemically produced. Antioxidants containing a
phenol group play a prominent role in biological and food system (Shui &
Leong, 2004).
The naturally occurring antioxidant substances are at times associated
with the beneficial effects of foods (Vision et al., 1999). They are avail-
able in complex forms, which include tocopherols, lycopenes, flavonoids,
nordihydroguaiaretic acid (NDGA), sesamol, gossypol, vitamins, provita-
mins and other phytochemicals, enzymes (catalase, glutathione peroxidase,
and super oxide dismutase), minerals (Zinc and Selenium), and lecithin
(Cuppett, 2001). α-tocopherol (vitamin E) is well known as one of the most
efficient naturally occurring lipid-soluble antioxidants (McCarthy et al.,
2001). The most important natural antioxidants commercially exploited are
tocopherols, ascorbic acid and more recently plant extracts, such as, from
sage (Djarmati et al., 1991), rosemary (Tena et al., 1997), green tea (Chen
et al., 2004), spinach (Aehle et al., 2004), grape (Baydar et al., 2004), and
marigold (Cetkovic et al., 2004) are also gaining acceptance. These extracts
contain mainly phenolic compounds (e.g., flavonoids and phenolic acids),
and they are well known for their antioxidant (López et al., 2001; Gülçin et
al., 2003), antimicrobial (Gülçin et al., 2003), anti-ulcer, anti-carcinogenic
(Chen et al., 2004), anti-mutagenic, and anti-inflammatory (Caillet et al.,
2006) properties, as well as for reducing the risk of cardiovascular diseases
(Cetkovic et al., 2004; Louli et al., 2004).
The antioxidant effects in milk rely primarily on endogenous compounds
(Brien & Connor, 2003). However, synthetic antioxidant compounds are
also widely used to inhibit progress of lipid oxidation. Some of the popular
synthetic antioxidants used in many countries including India are Butylated
Hydroxyanisole (BHA), t-butylhydroquinone (TBHQ), and esters of gallic
acid (Yanishlieva-Maslarova, 2001). These are mainly phenolic compounds
whose structure allows them to form low-energy radicals through stable
resonance hybrids that prevent the further propagation of the oxidation
reaction (Karovicova & Simko, 2000). Butylated hydroxytoluene (BHT) is
very effective in animal fats, low-fat food, fish products, packaging mate-
rials, paraffin, and mineral oils but is less effective in vegetable oils, and is