Studies on the Antioxidant Activity of Foods and Food Ingredients by Thin-Layer Chromatography–Direct Bioautography with 2,2′-Diphenyl-1-Picrylhydrazyl Radical (DPPH*)

This chapter reviews published research on the determination of antioxidant activity of foods and food ingredients using thin layer chromatography (TLC) and high performance TLC (HPTLC) with direct biodetection using 2,2’-diphenyl-1-picrylhydrazil radical (DPPH*). Covered topics include advantages of the TLC-DPPH* bioassay over high performance column liquid chromatography (HPLC) and the materials and instruments, and techniques that have been used for TLC/HPTLC -DPPH*, including sample preparation, types of plates used as the stationary phase, sample and standard solution application to the plates, methods used for choosing the mobile phase, development of the plates with the mobile phase, detection of zones with DPPH* reagent, chromatogram documentation, quantification with a slit scanning densitometer or by image analysis, and hyphenation with mass spectrometry. Selected applications to the study of antioxidant activity of manufactured and natural foods and food ingredients are then described, followed by a discussion of future prospects for analysis of antioxidant activity of foods by TLC/HPTLC.