Cold Brew Concentrate — A No-Heat Method for Smooth Coffee

Cold brew is the simplest brewing method in coffee. No kettle, no scale timing, no pouring technique. Just coffee, water, time, and a strainer. What it lacks in ritual it makes up for in consistency — the results are nearly impossible to mess up, and the concentrate lasts for weeks.

Why Cold Brew Works

Heat extracts coffee compounds rapidly and indiscriminately — desirable flavors alongside bitter, astringent ones. Cold water extracts more slowly and selectively. The acids and bitter compounds that give hot coffee its bite are less soluble at low temperatures, so cold brew produces a naturally sweet, low-acidity concentrate that tastes smooth even black.

This also means cold brew forgives mediocre beans. A $10 bag of supermarket coffee brewed cold will taste better than the same beans brewed hot. Good beans still matter, but the gap between good and bad beans narrows significantly with cold extraction.

The Ratio

The standard cold brew concentrate ratio is 1:8 by weight — 1 gram of coffee for every 8 grams of water. In practical terms:

• Small batch: 60g coffee / 500ml water (about 2 servings of concentrate)
• Standard batch: 100g coffee / 800ml water (3-4 servings)
• Large batch: 200g coffee / 1.6L water (week's supply)

These produce a concentrate meant to be diluted. Serve 1:1 with water or milk — adjust to taste. Some prefer 1:2 for a lighter drink. Start at 1:1 and experiment.

The Grind

Grind as coarse as your grinder allows — French Press setting, coarser than sea salt. Fine grinds over-extract even in cold water and produce a muddy, silt-heavy concentrate that's difficult to filter. If your cold brew tastes bitter or has visible sediment, grind coarser next time.

If you buy pre-ground coffee labeled "French Press" or "coarse," that works. Do not use espresso grind or standard drip grind — the resulting sludge will clog any filter you try to use.

The Method

1. Weigh and grind your coffee. 100g coffee, ground very coarse.
2. Combine coffee and 800ml room-temperature water in a large jar or French Press. Stir thoroughly to saturate all grounds. If using a jar, stir again after 5 minutes.
3. Cover and steep at room temperature for 18–24 hours. Shorter than 16 hours produces weak, under-extracted concentrate. Longer than 30 hours starts pulling bitter compounds. The sweet spot is 20 hours.
4. Strain through a paper filter, cloth filter, or fine mesh. Paper filters produce the cleanest cup but take the longest to filter — be patient, it will drip through eventually. Cloth filters are faster but let through more oils and micro-fines. A French Press plunger with a mesh screen works in a pinch but leaves silty residue — pour through a paper filter afterward if the silt bothers you.
5. Refrigerate the concentrate. It keeps for up to 2 weeks in a sealed container.

Serving

Pour 100ml concentrate over ice, add 100ml cold water or milk, stir. That's it.

Cold brew concentrate is also the base for coffee cocktails, affogatos (pour over vanilla ice cream), and coffee smoothies. It's versatile in a way hot coffee is not.

The French Press Shortcut

If you own a French Press, cold brew becomes even simpler. Add coffee and water to the press, stir, cover with the plunger raised, steep 20 hours, then press and pour. The mesh screen does a decent first-pass filter. For a cleaner cup, pour the pressed concentrate through a paper filter afterward.

Worth Noting

Cold brew concentrate has significantly more caffeine than regular drip coffee — roughly double when served at 1:1 dilution. A 200ml serving of diluted cold brew concentrate can contain 200-300mg of caffeine, comparable to two cups of hot coffee. If you are sensitive to caffeine, dilute further or serve in smaller portions.