Optimization of polyphenols extraction from orange peel

The aim of the present study was to optimize the phenolic recovery from orange peel by investigating the effect of several parameters on the extraction yield. The phenols were extracted in a batch reactor and the effects of the concentration and the nature of the solvent (methanol, ethanol and hexane: 0-100% V/V), were studied. The Folin-Ciocalteau reagent (FCR) was used for the determination of the total phenolic content (TPC) and the antioxidant activity was investigated using the stable free radical: 2,2-diphenyl-1-picrylhydrazyl (DPPH). TPC corresponds to the gallic acid equivalent (GAE)/g dry weight (DW) and its value (115.52mg) was obtained at 25 degrees C with a stirring speed of 400rpm in neutral medium (pH6) and a particle size of 605 mu m. The results indicated that the polyphenols content varies considerably with the solvent polarity and the highest extraction yield was obtained with aqueous organic solvent. The inhibitory concentration (IC50) obtained for DPPH inhibition was found to be 0.5%, while the DPPH inhibition showed a noticeable inhibitory activity of orange peel with a percentage of 97%; such high value constitutes an originality of the present study.