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?簡單回答：一般說茶裡的「單寧」，多半是指茶多酚，其中以兒茶素為主，它們會讓口腔有收斂、乾澀的感覺，也就是「澀」。「苦」則主要來自咖啡因，部分兒茶素也會帶苦味。當水溫太高、浸泡太久或茶葉放太多，這些成分萃取過量，茶湯就會變得苦澀。 ■ 澀和苦不一樣・澀：舌頭與口腔有乾、緊、收斂的感覺，主要來自茶多酚（兒茶素）。・苦：舌根感受到的苦味，主要來自咖啡因。適量的澀與苦是茶的骨架，過量才會變成缺點。 ■ 茶湯變苦澀的常見原因・浸泡太久：時間越長，茶多酚與咖啡因溶出越多。・茶葉太多：茶水比例太高，茶湯過濃。・茶葉太碎：碎葉表面積大，萃取速度快，容易過頭。・泡完沒取出茶葉：茶葉留在茶湯裡會持續萃取。・水溫不對：綠茶較細嫩，用太燙的水會加快苦澀成分溶出。Frastea 建議綠茶 85°C、紅茶 95–100°C。 ■ 怎麼減少苦澀・固定茶水比例與浸泡時間，泡好就把茶葉和茶湯分開。・做奶茶要濃時，優先增加茶葉量，而不是拉長時間。・商用門店建議用定溫、定時的萃取方式，讓每一杯的萃取程度一致。 ■ Frastea 的做法 Frastea 採用定溫、定時、加壓的鮮萃方式萃取茶湯，以精準溫控降低咖啡因與單寧帶來的刺激感，讓茶湯保留香氣、口感更圓潤。延伸閱讀：〈奶茶最適合用什麼茶原料？〉