Definition:
Cold brew tea is a slow-extraction brewing method in which loose-leaf tea or tea bags are combined with room-temperature or refrigerated water (2–25°C) and left to steep for 4–24 hours without heat, producing a brew that is distinctly smoother, sweeter, and lower in astringency and caffeine than the same tea prepared with hot water. Cold extraction favours amino acids and certain aromatic compounds while strongly suppressing catechin and caffeine solubility, making otherwise-astringent teas mild and approachable.
Brewing Guide
Cold Brew Parameters by Tea Type
| Tea Type | Tea Amount | Water Volume | Temperature | Time | Notes |
|---|---|---|---|---|---|
| Japanese green (Sencha, Gyokuro) | 6–10g | 500ml | 2–5°C (fridge) | 6–12 hours | Gyokuro cold brew extraordinary sweetness |
| Chinese green (Longjing) | 5–7g | 500ml | 15–20°C (room temp) | 4–8 hours | Room temp fine; fridge slows |
| White tea (Bai Mudan) | 5–7g | 500ml | 2–8°C | 8–24 hours | Extended cold brew intensifies delicacy |
| Oolong | 6–8g | 500ml | 4–10°C | 8–16 hours | Floral oolongs especially good cold brewed |
| Black tea | 8–12g | 500ml | 4–10°C | 6–12 hours | Less dramatic benefit than greens; still smooth |
| Puerh | 8–10g | 500ml | 4–10°C | 8–16 hours | Shou puerh makes smooth, earthy cold brew |
In-Depth Explanation
Extraction chemistry: The solubility of catechins (responsible for astringency), caffeine (bitter alkaloid), and certain tannins all decrease significantly at lower temperatures. Amino acids — particularly L-theanine, responsible for sweetness and umami — are much more soluble at low temperatures. This is why cold brew tea of the same leaf tastes sweeter and smoother than its hot-brewed counterpart despite longer steeping time.
Catechin extraction reduction: Studies show catechin extraction in cold water at 4°C is approximately 30–50% lower than hot water extraction using the same leaf and time, even when cold brew time is extended to 8–12 hours. Caffeine extraction is similarly reduced.
Room temperature vs. refrigerator: Room temperature cold brew (15–25°C) is faster — 4–8 hours typically — but has a slightly higher astringency than refrigerator cold brew. It should not be left longer than 8 hours without refrigeration for food safety reasons. Refrigerator cold brew (2–8°C) can steep safely for 24 hours or longer.
Mizudashi (水出し): In Japanese tea culture, cold water extraction specifically of gyokuro and high-grade sencha using cold water is called mizudashi (水出し, “water extraction”). Gyokuro steeped at 2–5°C for 8–12 hours develops extraordinary sweetness with essentially zero bitterness.
Not the same as iced tea: Iced tea brews hot and pours over ice (rapid dilution); cold brew tea never uses heat. The flavour profiles are fundamentally different.
History
Cold water tea extraction has likely existed in folk practice for centuries — leaving tea leaves in a water jar overnight is an obvious technique. The formalized category of “cold brew tea” as distinct from “iced tea” became popular in the specialty tea market approximately 2010–2018, driven partly by the success of cold brew coffee and by Japanese mizudashi marketing to Western audiences. Japanese supermarkets have sold cold brew tea bags (sararacha teabag formats) since at least the 1990s.
Common Misconceptions
“Cold brew is caffeine-free”: False — cold brew contains caffeine. Caffeine extraction is reduced (roughly 30–50% compared to hot brew), but not eliminated. It remains a caffeine-containing beverage.
“Cold brew needs expensive tea”: Good cold brew can be made with grocery-store green or white tea bags, since the cold extraction smooths out low-quality astringency. However, premium teas respond even better.
“Cold brew tea keeps indefinitely”: No — cold brew tea should be consumed within 3–5 days (refrigerated). Microbial growth in a protein-rich brewed tea is a real concern.
Social Media Sentiment
Cold brew tea is strongly positive in health-focused social media — “cold brew matcha latte” and “cold brew gyokuro” are frequently cited as wellness beverage alternatives to coffee. The simplicity (just combine leaf and water in a jar, refrigerate overnight) aligns well with the “set it and forget it” aesthetic of TikTok preparation content.
Last updated: 2026-04
Related Terms
See Also
- Sakubo — Japanese Language Learning (mizudashi is often a cultural knowledge topic for Japanese learners)