Red and Blue Light During Withering Changes White Tea's Taste, Study Finds
A study in Foods reports that the red-to-blue ratio of LED light used during withering measurably changes white tea's bitterness, astringency, and sweetness.
Withering white tea under different colours of light-emitting-diode (LED) light measurably changes the finished tea's taste, according to a study published on 3 March 2026 in the journal Foods.
The researchers, led by Dan Wu, compared six withering treatments: a control withered under an incandescent lamp, and five combinations of red and blue LED light.
Withering is the step in which white tea is made, the hours in which the fresh leaf loses moisture. The tea is otherwise only withered and dried.
The treatment with a red-to-blue light ratio of 3 to 1, labelled S4, achieved the highest overall score in sensory evaluation, with the lowest bitterness and astringency of any treatment. A 1-to-1 ratio, labelled S3, scored highest for sweetness and freshness alone, the researchers found.
Comparing the incandescent-lit control against the S4 treatment, the researchers identified 52 significantly changed metabolites.
The S4 treatment held the lowest levels of non-ester catechins, ester catechins, caffeine, and gallic acid among the treatments. Those compounds are associated with bitterness and astringency, according to the study.
Across the LED treatments, 18 metabolites were consistently raised, most of them saccharides, which the researchers linked to sweetness.
The work is a preliminary laboratory result, not a change to how white tea is made today.
Sources: Foods (MDPI), Taste Modulation of White Tea by Red/Blue-LED-Assisted Withering Revealed via Non-Volatile Metabolomics; PubMed Central, PMC12984552.
Correction, 2026-07-16: An earlier version said the study's control was withered in the dark. The study's control (S0) was withered under an incandescent lamp at matching light levels, not in darkness.
Correction, 2026-07-16: An earlier version named epigallocatechin among the compounds lowest in the S4 treatment. The study names gallic acid, not epigallocatechin, alongside the catechins and caffeine.