Assessing the antioxidant capacity of Ganoderma-infused white tea via electrochemical sensing techniques

Abstract

This study presents a novel electrochemical method for assessing the antioxidant capacity of Ganoderma-infused white tea using carbon black-gold nanoparticle (CB-AuNP) modified glassy carbon electrodes and in situ generated superoxide radicals. The CB-AuNP nanocomposite was characterized using scanning electron microscopy and cyclic voltammetry, revealing an increased electrochemical active surface area of 0.158 cm2, which is 2.2 times larger than that of the bare glassy carbon electrode. Optimal conditions for superoxide radical generation were established using the xanthine oxidase-hypoxanthine system (0.10 U/mL XOD, 0.5 mM HX, 10 minutes incubation). The antioxidant capacity of Ganoderma-infused white tea was evaluated using cyclic voltammetry and chronoamperometry, and expressed as Trolox equivalent antioxidant capacity (TEAC). The proposed method demonstrated a strong linear relationship between TEAC values and Ganoderma extract concentration (R2 = 0.9995), with TEAC values ranging from 0.54 ± 0.03–2.85 ± 0.12 mM Trolox/g tea for 0.1–1.0 % w/v Ganoderma-infused white tea. The method exhibited good agreement with conventional spectrophotometric assays (DPPH, ABTS, and FRAP), showing strong correlations (R > 0.997) for all three assays. The practical applicability of the method was validated using commercial tea products, revealing a positive correlation between antioxidant capacity and Ganoderma polysaccharide content (R = 0.9958). The proposed electrochemical method offers a rapid, sensitive, and reliable approach for assessing the antioxidant capacity of functional tea products, with potential applications in quality control and product development.