Metabolomics profiling of black tea and its antioxidant activity using proton nuclear magnetic resonance

Ensuring food quality is essential for consumer health and sensory appeal, especially for staple beverages like tea, which is an integral part of the daily diet for millions worldwide. Tea quality evaluation remains challenging due to its complex composition and the limitations of traditional sensory methods. This has driven the adoption of metabolomics approaches, such as proton nuclear magnetic resonance (¹H NMR) spectroscopy, despite persistent challenges related to sensitivity and signal overlap. This study employs 1 H NMR spectra and multivariate analysis to assess the components of 34 black teas, combining quantitative and functional analyses. Solid-phase extraction enhances concentration and impurity removal, thereby facilitating the quantification, profiling, and classification of theaflavins (TFs). The TF fraction of each tea is tested for antioxidant activity, with correlations examined between activity levels, TF quantification values, and principal component scores. Gallate-type TFs primarily contribute to antioxidant activity, showing a positive correlation with the principal component 1 score. 1 H NMR-based quantitative analysis and profiling can be utilised as a novel analytical method in food science, offering potential for quality evaluation and product development in the food industry. • ¹H NMR and multivariate analysis assess components of 34 black teas quantitatively. • Solid-phase extraction enhances theaflavin quantification and profiling. • Theaflavin fraction analysed for antioxidant activity and correlation patterns. • Gallate-type theaflavins key contributors to antioxidant activity. • NMR offers a reproducible method for food quality evaluation.