What Is Cold Brew Coffee?

What Is Cold Brew Coffee?

Cold brew is coffee made without ever touching hot water. Coarse-ground beans steep in room-temperature or cold water for an extended period, then get filtered.

Two methods dominate. Immersion brewing submerges the grounds fully in water before straining, and it is the most common approach for both home and commercial production. Slow-drip brewing, sometimes called Kyoto-style after a Japanese tradition that goes back centuries, lets water or ice drip slowly over a bed of grounds; sources describe it as producing a clearer, more aromatic cup than immersion.

Steep times commonly cited run from 12 to 24 hours for immersion, with slow-drip setups often finishing in 6 to 12 hours.

Cold Brew vs. Iced Coffee

Cold brew and iced coffee are not the same drink. Iced coffee starts as hot-brewed coffee that is later cooled over ice, so the grounds do get exposed to heat at some point. Cold brew never touches hot water at any stage; the entire extraction happens at room temperature or below.

The difference goes beyond temperature: what the water pulls out of the grounds also changes, which is why the two drinks taste different.

Why the Taste Differs

Temperature changes how quickly compounds dissolve out of the grounds. Food-science research from Pennsylvania found that cold and hot brews land at a similar pH, but hot brew consistently shows higher total titratable acidity, meaning cold brew's smoother taste comes from extracting less of certain acidic compounds rather than from a different pH.

The same research group found that, under their brewing conditions, coarse-grind cold brew actually carried more caffeine than hot brew made from the same beans, and that caffeine and chlorogenic acid levels reached equilibrium within 6 to 7 hours rather than the 10 to 24 hours typical recipes call for. In short, caffeine content swings with grind size, roast level, steep time and the coffee-to-water ratio rather than sitting at one fixed number.

Grind, Ratio, and Concentrate

Cold brew calls for a coarse grind; a fine grind combined with hours of steeping tends to over-extract and leave the cup cloudy and heavy with sediment. Coffee-to-water ratios vary widely across recipes, with no single fixed standard.

Most cold brew is prepared as a concentrate and diluted with water, milk, or ice before serving, which is why one batch stretches across several servings. Despite its name, it does not have to be served cold: the concentrate can be warmed and served hot, though it is usually served over ice or diluted cold.

Nitro Cold Brew

Nitro cold brew is regular cold brew charged with nitrogen gas and poured from a tap, which gives it a dense, beer-like foam. The style emerged at independent coffee shops in the early 2010s and is typically served without ice, since ice would break down the foam.