Analysis of Antioxidant
Properties of Popular
Beverages
acid, carotenes and glutathione. Total
antioxidant capacity can be measured
with a simple photometric assay based
on the reduction of bivalent copper ion,
Cu2+, to Cu+ by the antioxidants present
on the sample. This reduced form of
copper is then selectively bound to a
chromogenic compound to form a
complex that has strong absorbance at
490 nm.
Introduction
Antioxidants are
molecules capable of
slowing or preventing
the oxidation of other
molecules,
therefore
protecting cells
from oxidation
damages. There
are many claims
that various teas
and juices have
antioxidant
properties. Using
a simple analysis, we are able to
determine the antioxidant properties of several beverages.
Commonly known examples of antioxidants are vitamins E and C, uric
Method
The antioxidant power of different
beverage samples was determined using
a photometric Total Antioxidant Power kit
from Oxford Biomedical Research Inc.,
and a 96-well Thermo Scientific Immulon
1B microplate. The most commonly used
reference antioxidant, Vitamin B analogue
Trolox [(±)-6-hydroxy- 2, 5, 7,8-
tetramethylchromane-2-carboxylic acid]
was used as a calibration standard. All
beverage samples were diluted 1: 10 for
the testing and the assay was performed
according to kit instructions using the
Thermo Scientific Multiskan® FC
photometer and the Thermo Scientific
SkanIt® Software. After the measurement
the background absorbance was
subtracted from the final absorbance
values and a linear calibration curve was
prepared based on the standards. The
antioxidant power of the samples was
then resolved from the calibration curve
as Trolox equivalents.
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