Rapid quantitative evaluation of antioxidant activity using terahertz spectroscopy and microfluidic Technology: A study of Butylated hydroxyanisole

• Spectral techniques reveal the crystal structure and vibrations of Butylated hydroxyanisole. • Microfluidic chip uncovers hydrogen transfer in antioxidant action. • Mass spectrometry confirms phenolic hydroxyl decomposition in antioxidant process. • THz absorption peak shifts directly reveal emerging oxidation products. • THz rapidly quantifies compounds’ radical scavenging capacity. Butylated Hydroxyanisole (BHA) is a synthetic phenolic antioxidant widely used in food processing to extend the shelf life of food. We have developed a rapid and effective terahertz (THz) based method for investigating the antioxidant mechanisms of compounds and quantitatively assessing their free radical scavenging capacity. We initially characterized the crystal structure of BHA using multiple spectroscopic techniques, confirming the absence of oxidative degradation and thereby ensuring sample purity throughout the experimental process. Subsequently, combining THz time-domain spectroscopy (THz-TDS) with density functional theory (DFT), we analyzed functional group vibrations and identified the origin of key absorption peaks. Finally, a microfluidic chip monitored the structural changes of BHA during radical oxidation in real-time, revealing phenolic hydroxyl decomposition and new compound formation, suggesting hydrogen atom transfer (HAT) as a potential mechanism. Reaction products were analyzed using LC-MS and HPLC. A strong correlation (R 2 = 0.90924) between THz absorption and oxidation product concentrations was established, confirming the reliability of THz-TDS system for non-destructive antioxidant activity quantification. This study indicates THz technology provides an innovative and efficient method for evaluating antioxidants, laying the foundation for rapid and accurate assessment of food antioxidant properties.