Page 62 - Natural Antioxidants, Applications in Foods of Animal Origin

Natural Antioxidants: Occurrence and Their Role in Food Preservation 41
VetBooks.ir ABSTRACT

Antioxidants neutralize or inhibit free radicals by preventive and radical
scavenging modes. Free radicals are unstable reactive molecules; rapidly
attack the molecules in nearby cells leading to aging of body. The repair
process involves scavenging free radicals by antioxidant compounds. Anti-
oxidants have dual role: shelf-life prolongation and combating oxidative
stress. Consumers’ concerns regarding the bio-safety of synthetic antiox-
idants have pushed the food industry to seek natural alternatives such as
ascorbic acid (AA), tocols, carotenoids, phenolics, oryzanol (OZ), and so
forth. In contrast to animal foods, foods of vegetable origin usually contain
natural antioxidants, such as tocopherols, carotenoids, or flavonoids in suffi-
cient amounts due to higher degree of unsaturation. Natural antioxidants
provide preservative action in various foods, namely cereal based breakfast
foods, baked foods like bread and crackers, dried products, and processed
fruit products. This chapter provides full insight on different naturally occur-
ring antioxidants’ structure, levels, and effectiveness as food preservative.

2.1 ANTIOXIDANTS: WHAT, WHY, AND HOW

Antioxidants are compounds which neutralize free radicals or inhibit free
radicals. Free radicals are unstable molecules with an unpaired electron
and highly reactive. To become stable, they take electron from other mole-
cules/cells and in the process eventually damage the DNA and cause aging,
degenerative diseases, and may also lead to cancer. Free radicals can be
classified as reactive oxygen species (ROS) and reactive nitrogen species
(RNS). Few examples of ROS are alkoxyl radicals (RO ), peroxyl radicals
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(ROO ), hydroxyl radical (HO ), and superoxide anion radical (O ) while
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examples of RNS would be nitric oxide radical (NO ) and nitrogen dioxide
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radical (NO ). Potential sources of free radicals could be ultraviolet (UV)
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or ionizing radiations, metabolic processes, inflammatory reactions, air-
pollution, and tobacco (smoking or chewing). ROS are formed in vivo both
usefully and “accidentally.” Their formation increases in all human disease,
and sometimes makes a significant contribution to disease severity (Halli-
well, 1995). Free radicals damage the cell molecules like DNA, proteins,
and lipids, potentially causing a variety of disorders, including diabetes
mellitus, hypertension, cancer, Alzheimer, and aging of body. Free radicals
like ROS and RNS are generally produced due to the oxidative stress in the
body. The oxidative stress leads to over 200 disorders including aging of