Elucidating the photo-induced fading mechanism in green tea beverages: Metabolomics-guided discovery, quantification, and spiking validation of critical metabolites

The color of tea beverages is a critical quality determinant, yet photo-induced fading has received little attention compared to browning reactions. This study investigated riboflavin photodegradation in unsweetened green tea beverages under both retail-shelf lighting and simulated solar radiation. Under retail-shelf lighting, approximately 90% of riboflavin degraded within the first 5 days of a 20-day exposure period ( p  < 0.05), confirming its high susceptibility under realistic retail conditions. Under simulated solar radiation, a comparable 90% degradation occurred within only 8 h. Chlorophyll also degraded by approximately 37.5% after 8 h of sunlight exposure. While riboflavin serves as the primary driver of chromatic deterioration, chlorophyll contributes to a lesser extent in the photo-induced fading process. These findings establish riboflavin as a key target for intervention, with chlorophyll as a secondary contributor, providing a theoretical foundation for developing targeted light-protective strategies to preserve the color quality of green tea beverages.