2.10. Determination of antioxidant activity
The antioxidant activity of the juice was assessed using the
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.
The electron donation capacity of the extracts was measured by
bleaching of the purple-colored solution of DDPH radical according
to the method of Hanato, Kagawa, Yasuhara, and Okuda (1998).
One millilitre of extract (with different concentrations) was added
to 0.5 ml of a 0.2 mmol/l DPPH methanolic solution. The mixture
was shaken vigorously and kept at room temperature for 30 min.
The absorbance of the resulting solution was then measured at
517 nm. The antiradical activity was expressed as IC50 (lg/ml),
the concentration required to cause a 50% DPPH inhibition.
The ability to scavenge the DPPH radical was calculated using the
following equation:
DPPH scavenging effect ðI%Þ ¼ ½ðA0 A1Þ=A0 100
where A0 is the absorbance of the control at 30 min and A1 is that of
the sample at 30 min.
BHT was used as a positive control. Samples were analyzed in
triplicate.