Antioxidant Activity and Capacity Measurement

Measurement of antioxidant activity/capacity of foods and biological fluids is important for the determination of nutritional value of foods and for the diagnosis of diseases associated with oxidative stress. Antioxidant activity/capacity can be monitored using assays with different mechanisms, including (i) electron transfer-based assays, (ii) hydrogen atom transfer-based assays, (iii) mixed-mode assays, (iv) lipid peroxidation assays, (v) ROS/RNS scavenging assays, (vi) oxidative stress biomarkers and cellular-based assays, and (vii) chromatographic, chemometric, and electrochemical assays. In this chapter, the mechanisms of the most widely used analytical approaches for the measurement of antioxidant activity/capacity are discussed together with their advantages and drawbacks. Overall, measurement of antioxidant activity/capacity, in particular for mixtures, multifunctional or complex multiphase systems, cannot be evaluated satisfactorily with a simple antioxidant assay due to the several variables affecting the results. Therefore, it is recommended to apply several assays with different mechanisms in order to reveal the full capability of an antioxidant sample.