Hot-Air Withering Beats Tradition on Taste, Study Finds
A metabolomics study in Frontiers in Nutrition found hot-air withering produced better taste scores and more amino acids and catechins than traditional room-temperature withering.
Hot-air withering at 28 degrees Celsius (about 82 Fahrenheit) scored best on taste among four withering methods tested, a study published Thursday found.
White tea is withered, then dried. Nothing is rolled, nothing is fired, nothing is added. The withering room is the only place the maker acts, so hours and degrees are close to the whole of the decision.
The study, in Frontiers in Nutrition, compared traditional withering at 20 degrees Celsius (68 Fahrenheit) for 40 hours against three heated treatments held at 28 degrees: hot air for 23 hours, sunlight for 28 hours, and a fluorescent lamp for 31 hours. Hongchun Cui and six co-authors identified 1,372 metabolites across the four.
The leaf was Longjing 43, a cultivar grown for pan-fired green tea. It is not a white tea trade cultivar, and the researchers used it as a controlled substrate to isolate the withering variable rather than to make a commercial white tea. The work does not concern Fuding or Zhenghe production, and no new product follows from it.
All three heated treatments raised organic acids, amino acids, flavonoids and catechins against the room-temperature control, the researchers found. Between the heated methods, hot air's amino acids and flavonoids ran higher than the fluorescent lamp's, which the researchers said may explain its edge in the taste scores. Hot air also finished soonest, in 23 hours against the traditional method's 40. Set against the traditional method alone, the pathways most altered were cysteine and methionine metabolism, glutathione metabolism, and isoquinoline alkaloid biosynthesis.
Our withering guide records an existing commercial practice, indoor heated withering, run at 38 to 40 degrees Celsius (about 100 to 104 Fahrenheit) for about a day. The regime tested here ran cooler, at close to the same length. It is a second reading on the same question, taken lower down the scale.
Sources: Frontiers in Nutrition, Non-volatile metabolomics analysis of heating withering method for processing white tea from Longjing 43 tea variety by UHPLC-Q-TOF/MS; Crossref, 10.3389/fnut.2025.1735183.