Spectrophotometric and Electrochemical Assessment of the Antioxidant Capacity of Aqueous and Ethanolic Extracts of Citrus Flavedos

Citrus peel residues are of great interest due to the use of their extracted compounds in the food, pharmaceutical and cosmetic industries, mainly due to their antioxidant properties. The flavedo of this peel is especially relevant in modern culinary uses. The antioxidant capacity of the water and ethanolic extracts of the flavedos of ten peels was measured by a spectrophotometric assay and two electrochemical assays. The Folin–Ciocalteu values and ascorbic acid contents were also determined. From the results, it was concluded that the polyphenols extracted from the flavedos have antioxidant activities that occur through single-electron-transfer (SET) mechanisms rather than SET+ hydrogen atom transfer mechanisms. The polyphenols with high polarities extracted in the water constituted the least abundant fraction, and were better antioxidants than those with lower polarity extracted in the ethanol, which constituted the most abundant fraction.