Page 299 - Natural Antioxidants, Applications in Foods of Animal Origin

278 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir terpenoids, and phytomicronutrients (Podsędek, 2007; Serrano et al., 2007;

Pérez-Jiménez et al., 2008).
The interest for the natural antioxidants can be explained either because
of their capacity to ameliorate the quality of food and cosmetic products,
and also more recently because of their potential role in vivo against free
radicals, via feeding (health-food notion) or medication. The great diversity
of antioxidant sources observed in the plant world can be explained for the
phenolic compounds are largely expanded, and are found in every part of
plant: flowers, fruits, grains, leaves, bark, and roots. The efficacy, however,
depends not only on the amount of phenolic acids and flavonoids, but also of
tocopherol (vitamin E), ascorbic acid (vitamin C), and β-carotene content.
Sources of β-carotene include fruits, vegetables, dairy products, eggs, and
a few seafoods. Fresh fruits and green vegetables are particularly rich in
vitamin C. The crude oils, mainly that of wheat germ and nuts, are very
good sources of vitamin E. The active components of natural plant-derived
antioxidants are polyphenolic compounds. The most effective antioxidants
are those that contain two or more phenolic hydroxyl groups (Dziedzic &
Hudson, 1984; Shahidi et al., 1992). Plant phenolics compounds can either
act as reducing agents, free radical terminators, metal chelators, or O 2
1
quenchers.
The antioxidants obtained from spices and herbs (oregano, thyme, dittany,
marjoram, lavender, and rosemary) were reported to have limited applica-
tions in spite of their high antioxidant activity, as they impart a characteristic
herb flavor to the food, thus deodorization steps are required (Reglero et al.,
1999). Since many plant-derived substances often have a strong, distinctive
taste of their own, plant-derived antioxidants must not only be tested for
their ability to retard oxidation but also for any sensory characteristics they
impart to the food product. Naturally occurring antioxidant substances also
need safety testing. Caution regarding an assumption of safety of natural
antioxidants has been repeatedly advised, since the fact that an antioxidant
comes from a natural source does not prove its assumed safety. Hattori et
al. (1998) summarized the requirements that antioxidants must satisfy to be
used as food additives.

7.9 APPLICATION OF NATURAL ANTIOXIDANTS IN VARIOUS
DAIRY PRODUCTS

Dairy products contain lipids rich in PUFA and their esters are easily oxidized
by molecular oxygen over time. Deleterious changes in dairy products