Development of a Rapid Method for the Evaluation of DPPH Radical Scavenging Activity of Ginger (Zingiber officinale) Foods Based on Cyclic Voltammetry

A new and rapid method based on cyclic voltammetry (CV) was proposed for the evaluation of 2,2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity (RSA) of ginger (Zingiber officinale Roscoe) foods. The extraction conditions of samples were optimized by an orthogonal L-9(3)(4) test. Under optimum condition (methanol, solid-liquid ratio 1:3 and ultrasonic for 30 min), the ginger extracts were prepared and the electrochemical parameters of extracts were determined. The results show that two electrons and two protons are involved in the electrochemical oxidation. The evaluation method of DPPH-RSA was developed using the CV method. Eight kinds of ginger foods were evaluated using the proposed method. The results from the CV method and the classical spectroscopic method show insignificant difference (<+/- 3 %), yet the former method is superior in mean RSD and time efficiency. This suggests that the CV method is suitable for a rapid detection of DPPH-RSA, which is of significant importance for applications in both academic and industrial laboratories.