Cold Brew
A smooth, heavy, chocolatey coffee with almost no sharpness, made by leaving ground coffee in cold water overnight. You make a concentrate, keep it in the fridge for a week, and dilute a glass at a time.
At a glance
- Coffee : water
- 1:8
- Active time
- 10 min
- Total time
- 970 min
- Makes
- 8 glasses
- Serve
- Over ice, diluted
- Kit
- Jar + filter
Ingredients
Note: This makes about 650 ml of concentrate, because the grounds hold back some water. Dilute one to one with cold water or milk to serve.
Method
-
Grind coarse
Grind the coffee coarse, the setting you would use for a French press or slightly coarser.
Fine grounds over-extract in a long steep and turn the concentrate muddy and bitter, and they clog the filter.
-
Combine and stir
Put the coffee in the jar, pour over the cold water, and stir until every ground is wet. Dry clumps float and never extract.
-
Steep
Cover and leave it: twelve to fourteen hours at room temperature, or eighteen to twenty-four in the fridge.
Cold slows extraction, so the fridge version needs longer. Past about twenty-four hours, it starts to taste woody.
Steep 12 to 24 hours -
Filter it twice
Lift out the mesh insert or pour the coffee through a sieve, then pour it again through a paper filter. The second pass removes the fine silt that makes cold brew taste chalky by day three.
Filter 10 minutes -
Dilute and serve
Pour 100 ml of concentrate over ice and add 100 ml of cold water or milk. Taste, then adjust next time.
Keep the concentrate in a sealed bottle in the fridge and use it within ten days.
Why this works
Temperature changes what water pulls out of coffee. Many of the compounds that taste sharp, sour or harshly bitter dissolve much faster in hot water than in cold, while a good share of the sweet, heavy and chocolatey ones still come through slowly. Cold brew is therefore not hot coffee chilled. It is a different extraction, with a different balance, and that is why it tastes smoother and rounder. The trade is aroma. Many of the volatile compounds that make fresh hot coffee smell wonderful never form or never leave the grounds.
The acidity claim is widely repeated and partly true. A 2018 study from Thomas Jefferson University found that cold brew and hot coffee had similar pH, but hot brew had more titratable acidity, meaning more total acid in the cup. In plain terms, cold brew tastes less sharp, though it is not dramatically less acidic in the chemical sense.
A long steep in cold water needs a high dose to get anywhere, which is why the ratio is a concentrate at one to eight. Diluted one to one, it lands at a normal iced coffee strength. A coarse grind keeps the steep from over-extracting the woody, bitter compounds that eventually do come out after a day.
Cold brew is not new. Japanese Kyoto-style drip has existed for generations, and cold coffee extract was sold in the nineteenth century. What changed in the 2010s was scale. Cafés in the United States made it a menu staple, and it has since become one of the biggest growth categories in coffee.
Variations
- Cold brew with milk: concentrate one to one with cold milk, which is smoother than an iced latte.
- Nitro: charged with gas for a cascading, creamy pint. See nitro cold brew.
- Hot: concentrate one to one with boiling water, a quick low-acid hot coffee.
- Vanilla sweet cream: 30 ml single cream with 10 ml vanilla syrup, poured over the top.
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Questions
What is the best ratio for cold brew?
One to eight for a concentrate, by weight: 100 g of coffee to 800 ml of water. Dilute one to one to serve. For a ready-to-drink cold brew, use one to fifteen and do not dilute.
How long should cold brew steep?
Twelve to fourteen hours at room temperature, or eighteen to twenty-four hours in the fridge. Longer than about twenty-four hours tends to taste woody.
How long does cold brew keep?
Concentrate keeps about ten days in a sealed bottle in the fridge. Diluted, drink it within two or three days.
Is cold brew less acidic?
It tastes less sharp. Research has found a similar pH to hot coffee but lower titratable acidity, meaning less total acid. The difference you notice is mostly taste.
Does cold brew have more caffeine?
The concentrate is strong, but once diluted one to one, a glass usually lands roughly in the range of a cup of filter coffee. It depends entirely on the dilution.