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Natural Antioxidants: Occurrence and Their Role in Food Preservation 81
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TABLE 2.9 Natural Antioxidants Present in Cereal Brans (Rosa et al., 1999; Hídvégi and
Lásztity, 2003).
Nutrients (values/100 g) Rice bran Corn bran Oat bran Wheat bran
Vitamin E
Tocopherols (mg) 12.0 0.4 1.0 1.5
Tocotrienols (mg) 13.6 – – –
Total carotenoids (mg) 129.3 – – –
Gamma oryzanol (mg) 300.0 – – –
Phytosterols (mg) 341.1 – – –
Phytic acid (mg) 9500 620–1170 900–1420 520–1050

Aqueous extracts of natural antioxidants from other whole grains or
brans, tea extracts and fruit extracts may be used with good results (Baublis
et al., 2000a; Pokorný & Trojáková, 2001). The catalytic effect of iron is
eliminated by phytic acid (Baublis et al., 2000b; Pokorný & Trojáková,
2001). Natural amino acids—methionine and cystine, PL and uric acid—are
as active as synthetic antioxidants in breakfast cereals (Maestro-Duran &
Borha-Padilla, 1993; Pokorný & Trojáková, 2001). The nutritional value of
breakfast cereals is increased by the addition of flavonoids and related plant
antioxidants, which extend shelf life (Shukla, 1993; Pokorný & Trojáková,
2001). Breakfast cereals, fortified with vitamin A (a very unstable compound)
were efficiently stabilized with commercial phenolic natural antioxidants
(Fritsch et al., 1975; Pokorný & Trojáková, 2001). Browning products, often
present to improve the flavor of food products, may also help in their stabi-
lization. Another kind of cereal products are extruded products, such as flat
bread. Natural antioxidants may be added with flour and other additives to the
extruder barrel. They are thus uniformly distributed in the extruded product.
Spices are useful for stabilization as they impart interesting flavor notes to
the final product. The agreeable color of extruded snack products, mainly
due to carotenoids, rapidly disappears on storage. Therefore, it needs to be
stabilized. An oil-soluble liquid rosemary extract (4942 Rosmanox) and its
mixture with tocopherols (4993 Rosmanox E) preserved the natural color-
ation for more than seven months (Marcus, 1994; Pokorný & Trojáková,
2001). Various snacks are easily stabilized with salt-containing natural anti-
oxidants (Sharma et al., 1997; Pokorný &Trojáková, 2001). Some cereal
products contain added fat, mostly hydrogenated edible oil and/or fillings
also rich in fat. Even when hydrogenated oils are rather stable against oxida-
tion, off-flavors may arise on storage. Application of natural antioxidants