Exploring the taste code of light-withered tea: the mechanism of nonvolatile metabolite changes in LED light-withered...

Rainy weather hinders normal sunlight withering of oolong tea, which prevents the development of its high-quality characteristics. This study used representative oolong tea varieties ("Shuixian," "Ruixiang," and "Chunlan") and applied multi-wavelength LED combination light, with control group for sensory and metabolomics comparison experiments. Sensory omics results showed that LED light-withered oolong tea has a more mellow taste, with deeper orange-yellow and orange-red hues. Widely targeted metabolomics analysis revealed that LED light withering affected the taste of oolong tea by promoting transformation of key bitter-related metabolites, including flavonoids (Kaempferol-3-O-rutinoside, Epigallocatechin, Kaempferol, Robinin), alkaloids, bitter amino acids, and oligopeptides. These changes were accompanied by varying levels of umami and sweetness, resulting in more mellow taste. This research clarifies the relationship between metabolite changes and flavour enhancement following LED light withering, providing systematic theoretical foundation for the controlled light-withering of oolong tea under rainy conditions and its quality improvement.