From Quantity to Reactivity: Advancing Kinetic-Based Antioxidant Testing Methods for Natural Compounds and Food Applications

Traditional antioxidant testing methods primarily focus on quantifying antioxidant capacity but fail to capture their reactivity and effectiveness over time. Kinetic-based methods provide a deeper understanding of antioxidant performance by assessing reaction rates and inhibition mechanisms. This review discusses the advanced kinetic-based antioxidant testing methods, including the integration of kinetic modeling in traditional assays like 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity, along with inhibited autoxidation methods based on isothermal calorimetry, oxygen uptake, and differential photocalorimetry (DPC). The principles, advantages, and limitations of these methods are discussed, along with their applications. Additionally, challenges related to instrumentation, standardization, and practical implementation are highlighted. Various kinetic-based antioxidant testing methods have been developed, each with its own set of advantages and limitations. Despite these differences, all these methods share one significant advantage: the ability to provide detailed kinetic information on antioxidant behavior. Continuous monitoring of antioxidant reactivity enables a deeper understanding of how these compounds function in inhibiting oxidation. Furthermore, most of these methods allow testing in real food-based oxidizable substrates, enhancing their relevance for food applications. Although techniques such as oxygen uptake and DPC may be limited by throughput capacity, methods like isothermal calorimetry and oxidizable substrate monitoring offer high-throughput capabilities, making them suitable for large-scale screening. This review presents a range of kinetic-based antioxidant testing methods that can be chosen and applied according to specific experimental requirements and convenience, providing flexibility to address various food-related oxidation challenges.