The antioxidant activity (AA) of the extracts was evaluated in
terms of bleaching of the β-carotene using the following formula,
AA = 100 1− Ao−At
ð Þ= Aoo
−Aot
where Ao and Ao
o are the absorbance values measured at zero time of
the incubation for test sample and control, respectively. At and Aot
are
the absorbance measured in the test sample and control, respectively,
after incubation for 60 min. The results were expressed in % basis of
preventing bleaching of β-carotene.