What Are Tannins in Tea, and Why Does Tea Taste Bitter?茶裡的單寧是什麼？茶湯為什麼會苦澀？

Frastea · October 1, 20262026年10月1日

Short answer: when people talk about "tannins" in tea, they usually mean tea polyphenols, mainly catechins. These create a drying, puckering feeling in the mouth, which is astringency. Bitterness comes mainly from caffeine, with some catechins adding to it. When water is too hot, the tea steeps too long or too much leaf is used, these compounds are over-extracted and the tea turns bitter and astringent. ■ Astringency is not bitterness - Astringency: a dry, tight, puckering feeling on the tongue and gums, mainly from polyphenols (catechins). - Bitterness: a bitter taste at the back of the tongue, mainly from caffeine. In the right amounts both give tea its structure; only in excess do they become flaws. ■ Common causes of bitter, astringent tea - Steeping too long: the longer the steep, the more polyphenols and caffeine dissolve. - Too much leaf: a high leaf-to-water ratio makes the tea too strong. - Finely broken leaves: more surface area means faster extraction and easier over-brewing. - Leaves left in the cup: extraction continues as long as the leaves stay in the tea. - Wrong water temperature: green tea is delicate, and water that is too hot speeds up the release of bitter, astringent compounds. Frastea recommends 85°C for green tea and 95–100°C for black tea. ■ How to reduce bitterness - Keep a fixed leaf-to-water ratio and steep time, and separate the leaves as soon as the tea is ready. - For strong milk tea, add more leaf rather than steeping longer. - In commercial stores, use fixed-temperature, fixed-time extraction so every cup is extracted the same. ■ How Frastea brews Frastea extracts fresh tea with controlled temperature, controlled time and pressure, using precise temperature control to reduce the harshness of caffeine and tannins while keeping the aroma and a rounder mouthfeel. Further reading: What Is the Best Tea for Milk Tea?簡單來說，一般常聽到的茶中「單寧」，多半是指茶多酚（其中又以兒茶素為主），它們會讓口腔產生緊縮、乾澀的感覺，也就是我們常說的「澀」；而「苦味」則主要來自咖啡因，部分兒茶素也帶有微苦。當水溫拿捏不當、浸泡太久或茶葉放太多時，這些成分過度釋放，就會讓茶湯變得又苦又澀。 ■ 茶湯變苦澀的常見原因浸泡太久：時間拉長，茶多酚與咖啡因便會大量溶出。茶葉過量：茶水比例失衡，導致茶湯過濃。茶葉太碎：碎葉表面積大、釋放速度極快，容易過頭。未及時離水：茶葉留在杯中持續釋放物質。水溫不對：綠茶茶葉較細嫩，水溫過高會加速苦澀成分溶出（Frastea 建議綠茶使用 85°C、紅茶使用 95–100°C）。 ■ 怎麼減少苦澀？掌握時間：固定茶水比例與浸泡時間，茶湯泡好後馬上將茶葉與茶湯分開。調整濃淡：需要濃茶感（如做奶茶）時，應優先增加茶葉量，而不是拉長時間。規格化操作：商用門店建議採用定溫、定時的萃取方式，確保每一杯品質穩定一致。 ■ Frastea 的做法 Frastea 採用定溫、定時、加壓的鮮萃方式來萃取茶湯，透過精準溫控降低咖啡因與單寧帶來的刺激感，讓茶湯完整保留香氣，口感更加圓潤順口。（延伸閱讀：〈奶茶最適合用什麼茶原料？〉）