Oxidation & Roast
A Camera Can Now Grade How Fermented Your Tieguanyin Is
A 2026 study taught machine-learning models to read Tieguanyin's fermentation stage from ordinary photos and hyperspectral scans, graded against a two-of-three vote among tea masters, not a chemical threshold and not one expert's word alone.
The Stem Concentrates Floral Compounds the Leaf Does Not
A 2025 tissue-level study found oolong's stem holds more of the compounds behind its floral scent than the leaf beside it. A 2022 study found adding stem to the blend lowers one of those same compounds in the finished tea. Neither team was answering the other's question, and nobody has reconciled the two.
A Rainy Pick Day Caps a Rock Tea's Aroma, and No Roast Recovers It
A 2025 GC-MS study found rainy-day-picked Wuyi rock tea carries 40 to 74 percent less floral and fruity aroma compound than sunny-day leaf, and processing cannot fully make up the deficit.
A charcoal roast is a sequence of fires, rested months apart
Charcoal roasting is a sequence of separate fires, not one step, and each fire does distinct, measurable chemistry to the leaf. The practice also varies more across oolong styles than most tea copy admits.