What coffee should I buy for cold brew?

Cold brew — cold extraction over 12 to 24 hours — is a method that amplifies sweetness, tones down acidity, and concentrates the coffee's natural sugars. You need a coffee that benefits from these characteristics: medium roast, coarse grind, and naturally chocolatey, fruity, or sweet origins. Very light roasts produce unpleasant cold acidity; very dark roasts become overwhelmingly bitter over a long steep.

The chemistry of cold brew is fundamentally different from hot extraction. At low temperatures (4-20°C), chlorogenic acids — responsible for the acidity perceived as aggressive in an over-extracted hot coffee — are far less soluble. The result: cold brew is naturally less acidic, smoother, and richer in natural sugars. This property completely changes the coffee selection criteria.

The first criterion is roast level. A medium roast (light-medium to medium) is ideal: it preserves the fruity and chocolatey aromatic compounds that dissolve well in cold water. However, too light a roast will still produce unpleasant residual acidity even cold — because some organic acids (malic, citric) remain soluble at low temperatures. Too dark a roast releases bitter compounds (phenols, degraded chlorogenic acids) during long extraction that dominate and weigh down the cup.

The second criterion is origin. Naturally sweet and low-tannin coffees are the best candidates. Brazil (cerrado, south Minas arabica) — with notes of milk chocolate, nuts, and caramel — is the archetype of a cold brew coffee. Colombia (balanced profile, fruity sweetness) works very well. Natural process Ethiopia brings red fruit and berry notes that are highly appreciated. Sumatra (wet-hulled process) yields a thick, earthy, spicy cold brew. Conversely, highly floral and acidic coffees (some washed Kenyan or high-altitude washed Ethiopian) can taste flat or unbalanced in cold brew.

The third criterion is grind size. Cold brew requires a coarse grind — comparable to French press or slightly finer. Too fine a grind in a 12-24h extraction causes over-extraction even cold, making the cup bitter and tannic. The recommended coffee-to-water ratio is generally 1:8 to 1:10 for a concentrate (to be diluted) or 1:14 to 1:16 for direct consumption.

Finally, freshness matters, though cold brew is slightly more forgiving of a somewhat aged coffee than hot extraction. A coffee roasted 2 to 6 weeks ago (slightly off-gassed) is often ideal — too fresh, and residual CO2 can disrupt cold extraction. Artisan selections available from venues like 20hVin (La Hulpe) or La Cave du Lac (Genval) guarantee traceability and green quality that supermarket coffees cannot match.