Page 65 - Natural Antioxidants, Applications in Foods of Animal Origin

44 Natural Antioxidants: Applications in Foods of Animal Origin
VetBooks.ir 2. DPPH (2,2-diphenyl-1-picrylhydrazyl).

3. ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)).
4. FRAP (ferric ion reducing antioxidant power).

It should be noted that antioxidant activity of food extracts can be deter-
mined using a variety of tests (stable free radical scavengers: galvinoxyl,
diphenylpicrylhydrazyl (DPPH); lipid oxidation: peroxide oxygen, conju-
gated dienes, Rancimat (measurements of oxygen consumption of a linoleic
acid emulsion and oxidation induction period in lard at 100 °C), oxygen
radical absorbance capacity (ORAC) values), active oxygen method, iodine
value (IV) (measure of the change in number of double bonds that bind I),
anisidine value (reaction of acetic acid p-anisidine and aldehydes to produce
a yellow color that absorbs at 350 nm), measurement of absorbance at 234 nm
(conjugated dienes) and 268 nm (conjugated trienes) to assess oxidation in
the early stages, and chromatographic methods; however, extraction proce-
dures strongly influence the composition of the extracts and, therefore, also
influence the antioxidant activity results (Halliwell, 1996; Schwarz et al.,
2001; Trojakova et al., 2001; Brewer, 2011). In addition, the effect of the
antioxidant compound in a food matrix may be significantly different than
the activity of a purified extract (Brewer, 2011).

2.3 SYNTHETIC ANTIOXIDANTS VERSUS NATURAL
ANTIOXIDANTS

The use of synthetic antioxidants (such as BHA, BHT, PG, and TBHQ)
to preserve food products for a longer shelf life with retained quality and
organoleptic attributes has become common commercially. However, the
consumers’ concerns regarding their bio-safety have motivated the food
industry to seek natural alternatives. Synthetic phenolic antioxidants BHA,
BHT, PG, and TBHQ effectively inhibit oxidation by scavenging free radi-
cals. Chelating agents, such as EDTA, can bind radically active trace metals
reducing their contribution to the process. Some natural substances like
vitamins (AA, tocols, and phylloquinone), carotenoids, polyphenols/pheno-
lics, PS, sesame lignans, OZ, and phytic acid can also perform the role of
radical scavenging and metal ion chelating effectively and as efficiently as
their synthetic counterparts. Natural antioxidants, mostly absorb light in
the UV region (100–400 nm), can effectively scavenge free radicals, and
chelate transition metals, thus stopping progressive autoxidative damage
and production of off-odors and off-tastes in food products. Consumers