The antioxidant activity of ginger and turmeric powders derived from freeze-dried rhizomes and peels as well as commercial spices has been evaluated by two spectrophotometric assays based on electron transfer such as DPPH and FRAP. The phenolic characterization has been also carried out by detecting total polyphenols through Folin-Ciocalteu method and HPLC analysing 6-gingerol and curcumin. Ginger and turmeric peels showed greater antioxidant activity than commercial powders because of their higher phenolic yields. Hence, ginger and turmeric peels can be considered a rich source of phytochemicals which contribute to the antioxidant effects of these agro-food wastes.
Keywords: Antioxidant activity; Bioactive compounds; Ginger; Peels; Turmeric.