What is cold brew coffee?
Cold brew is coffee made by steeping coarsely ground beans in room-temperature or chilled water for 12 to 24 hours, then filtering. Cold extraction produces a naturally sweet, low-acid and very low-bitter cup because the acidic and bitter compounds stay largely insoluble in cold water.
Contrary to a common belief, cold brew is not a recent invention of the New York specialty scene. The oldest documented trace is Japanese, under the name 'Kyoto-style cold brew' or 'Dutch coffee', a slow cold drip method dating to the 17th century — Dutch merchants in Nagasaki likely introduced the technique to Dutch sailors. The modern immersion version took hold in American cafés around 2010-2012 and went global via chains like Stumptown.
The chemistry explains the cup profile. Cold extraction is dramatically slower than hot: it takes 12 to 24 hours at 4-20 °C to reach an extraction comparable to 4 minutes of French press at 93 °C. But the slowness is selective: chlorogenic acids (responsible for acidity and, when degraded, bitterness) are less soluble in cold water. A cold brew typically carries 60-70 % of the titratable acidity of a regular filter coffee. It is often easier on sensitive stomachs.
Caffeine content in cold brew is not intrinsically higher than hot — it is all about ratio. Cold brew recipes use more concentrated ratios (1:4 to 1:8 for a concentrate to dilute, 1:15 to 1:17 for ready-to-drink) because the liquid often serves as a base, cut afterward with water, ice or milk. A 1:4 concentrate can hit 200-300 mg of caffeine per 100 ml, two to three times a regular filter by volume — but it gets diluted.
In Belgium, cold brew appeared in specialty bars around 2014-2015, first in Brussels (Saint-Gilles, Ixelles) and then Ghent and Antwerp. It is especially popular from May to September iced, sometimes with maple syrup or cane sugar, or topped with oat milk for a cold brew latte. Nitro cold brew — cold brew infused with nitrogen for a Guinness-like creamy texture — landed in Belgium around 2017-2018.
Cold brew vs iced coffee vs Japanese iced
| Method | Extraction temp | Duration | Grind | Profile |
|---|---|---|---|---|
| Immersion cold brew | Room (15-20 °C) or fridge | 12-24 h | Coarse | Sweet, low-acid, concentrated |
| Kyoto-style slow drip | Room, drop-by-drop | 3-8 h | Medium | Clean, very aromatic |
| Nitro cold brew | Cold brew + N2 | 12-24 h + service | Coarse | Creamy, Guinness-like texture |
| Japanese iced V60 | Pourover onto ice | 3-4 min | Medium | Aromatic, bright acidity |
| Iced coffee (hot, then cold) | Standard hot brew over ice | Variable | Variable | Diluted, oxidised |
| Cold brew latte | Cold brew + cold milk | — | — | Smooth, creamy |