hui tian (tea rising sweetness)

Huitian is a term used in tasting ripe Pu-erh tea and similar teas for the gradual rise of sweetness in the mouth after a slight bitterness immediately on taking the tea into the mouth. A 2023 tea-industry article describes it as 「入口微苦、回味清甜(口に含むとかすかに苦く、後味は清らかに甘い)」 (in translation: "slightly bitter on entry, with a clear sweetness in the aftertaste (slightly bitter in the mouth, with a clear sweet aftertaste)"), presenting a sensation that shifts from bitterness to sweetness. The source, however, is an article by someone in the tea trade, not an academic paper.

Huitian is sometimes distinguished from huigan, another term used in tea tasting. A 2023 article contrasts them as 「回甘は化学的要因(苦味・渋味と甜味の相互作用)によるもの、回甜は物理的要因(茶多糖の働き)によるもの」 (in translation: "huigan results from chemical factors (the interaction of bitterness and astringency with sweetness), whereas huitian results from physical factors (the action of tea polysaccharides)"). A different article from 2018, however, explains huitian as physical stimulation of the taste buds by soluble sugars, sweet-tasting amino acids, and thearubigins; the details of the proposed distinction do not agree across sources. Parts of the two articles also use nearly identical wording, so they may not count as independent sources. The distinction between huigan and huitian needs to be treated as customary usage within the tea trade, not as standardized academic terminology.

Soluble sugars, sweet-tasting amino acids, and thearubigins (reddish-brown pigments formed through fermentation) are cited as possible causes of huitian, under a theory that they physically stimulate taste buds. This mechanism also comes from a republished tea-trade article, without verification by chemical analysis or controlled sensory testing.