Evaluation of antioxidant performance of economic crops by electrochemical sensors using guanine as a probe

Abstract

The evaluation of antioxidant performance in economic crops is of significant importance due to their potential health benefits and increasing demand for functional foods. In this study, we developed an electrochemical sensor based on guanine binding technology to assess the antioxidant capacity of common economic crops, including tomatoes, blueberries, spinach, grapes, and oranges. The guanine oxidation peak current, measured using square wave voltammetry on a composite film-modified electrode (RGO/G/GCE), served as an indicator of antioxidant activity. Statistical analysis, including one-way analysis of variance (ANOVA) and post-hoc tests, revealed significant differences (p < 0.05) in the guanine oxidation peak currents among the tested crops, highlighting variations in their antioxidant activities. Blueberries exhibited the highest guanine oxidation peak current, indicating the strongest antioxidant capacity, followed by spinach and grapes with significant antioxidant activity. Tomatoes and oranges displayed relatively lower antioxidant capacity. The working/linear range for the electrochemical sensor was determined to be 0.5–4.0 mg/L of ascorbic acid (AA), and the limit of detection (LOD) was calculated as 0.35 mg/L. The proposed electrochemical sensor provides a rapid, sensitive, and cost-effective approach for assessing antioxidant capacity, offering potential applications in quality control, nutraceutical analysis, and functional food development.