Cream down (milk down, or tea cream in some literatures) is an effect of precipitate formed after tea cools down. It usually happens in black tea or highly oxidized oolong tea. Some assert it is a sign of superior quality. However, there are also some literatures discussing how to eliminate cream down effect on ice tea (or beverage tea, usually cheap and low-qualitied in nature) since consumers prefer clean and crystal tea. These controvertial findings make me doubt if cream down effect is proper measurement of tea quality.
冷後渾是一種茶溫下降之後發生的沉澱現象，常出現在紅茶或高發酵的烏龍茶。有人宣稱 (越來越多人) 冷後混是高級紅茶的象徵。然而，很有趣的是，另外有一些文獻卻是研究如何消除茶飲料中的冷後渾現象 (茶飲料通常使用低級、低價的茶)，因為消費者比較喜歡乾淨清澈的茶湯。這些悖論的發現，讓我開始懷疑冷後渾是否為判斷茶品質的標準?
Below is little experiment I did to test if cream down effect could happen in cheap tea (or low quality tea).
- A Set: Brew a cheap black tea by a normal method (5 gram tea/ 150ml boiling water for 3 minutes), and put into a refrigerator to cool down to 5°C. (A組: 5公克茶配150ml滾水，泡3分鐘，放入冰箱將茶溫降至5°C)
- B Set: Brew the same cheap black tea by alternative method (10 gram tea/ 150ml boiling water for 5 minutes), and put into a refrigerator to cool down to 5°C.(B組: 10公克茶配150ml滾水，泡5分鐘，放入冰箱將茶溫降至5°C)
- The result: B set has significant cream down effect while A set has little. (結果: B組有明顯的冷後渾現象，A組不明顯)
I think it’s obviously cream down effect does not only happens in high qaulity tea. You could generate the same result with low quality tea if the concentration of tea is high enough.
After discussion with some friends and searching literatures online, below is what I have found from literrature on PubMed
- A higher tea concentration leads to earlier onset of creaming and larger particle. (較高的茶濃度有助於乳化現象的提早以及大量的形成)
- Theaflavin, caffeine and calcium are major factors of forming tea cream.(茶黃質、咖啡鹼以及鈣質是形成乳化現象的三種要素)
- Tea creaming may be reduced by increasing the solubility of the polyphenols or by removing calcium. (增加茶多酚的濃度，或是移除鈣質有助於減少乳化現象)
Since tea cream is originated by three factors: Theaflavin, caffeine and calcium. One could get suffcicient tea cream by increasing the theaflavin& caffeine in tea or adding calcium in water. Maybe I should rephrase the question:
Is higher theaflavin, caffeine and calcium make a better tea? And if yes? How is it to with to enhence our tasting experience in terms of aroma, flavor and balance of tea…ect?.
How do you think?
- Health benefits of black tea (abdifeisal.wordpress.com)