The antioxidant activity of fruit extracts (acerola, açaí, black-berry and strawberry) and pure compounds has been analysed by two methods: beta-carotene/linoleic acid and DPPH•(2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. First, those methodologies were adapted to be performed in microplates, in order to reduce the sample and reagent amounts, to increase the number of simultaneous analyses and to automate absorbance lectures. The results showed that the antioxidant activity of the fruit extracts was in accordance with those of pure ascorbic acid and phenolic compounds, in the two systems. The acerola extract, due to its high vitamin C content, acted as pro-oxidant, but açaí, black-berry and strawberry extracts acted as antioxidants in -carotene/linoleic acid system. However, by the DPPH• radical scavenging assay the acerola extract presented the highest antioxidant activity, followed by açaí, black-berrry and strawberrry. The adaptation of methods to evaluate the antioxidant activity using microplate allowed the realization of multiple analyses simultaneously and minimized significantly the use of reagents and samples.
antioxidant; fruit; DPPH•; beta-carotene; microplate; phenolics
