Cold Brew Coffee
Coarse grounds steeped in cold water for sixteen hours. Less bitter and less acidic than iced coffee, and it keeps a week.
Nutrition Info (per serving)
- 15
- Calories
- 1g
- Protein
- 0g
- Fat
- 2g
- Carbs
Ingredients
- 100 g coffee beans
- 1 litre cold filtered water
- Milk, to serve
- Ice
Instructions
- 1Grind the beans coarsely, about the texture of raw sugar. Fine grounds over-extract during a long steep and turn the brew muddy and bitter, and they are almost impossible to filter out.
- 2Combine the grounds and the cold water in a jar. Stir gently to make sure every ground is wet — dry pockets simply do not extract.
- 3Cover and leave at room temperature for 12 to 16 hours, or in the fridge for 18 to 24. Room temperature extracts faster and gives a fuller body; the fridge is slower and cleaner.
- 4Do not stir again during the steep. Agitation increases extraction unevenly and pulls out the bitter compounds you are avoiding.
- 5Strain through a fine sieve to remove the bulk of the grounds, then again through a paper coffee filter or muslin for a clear concentrate. The second pass is slow — leave it to drip rather than pressing it.
- 6What you have is a concentrate, roughly twice the strength of drip coffee. Dilute one part concentrate to one part water or milk over ice.
- 7Store in a sealed bottle in the fridge for up to a week.
Cold brew is not iced coffee. Iced coffee is brewed hot and then chilled; cold brew never sees heat at all, and the difference in the cup is significant.
Why it tastes less bitter
Temperature governs which compounds dissolve. Hot water extracts nearly everything, including the bitter compounds and many of the acids that give hot coffee its brightness and, sometimes, its harshness.
Cold water extracts far more slowly and selectively. The sugars and much of the caffeine come out over the long steep, while a good share of the bitter and acidic compounds are simply left behind in the grounds.
The result is measurably lower in acidity — often cited at around 60 percent less — and tastes rounder, sweeter and more chocolatey. It is also why people who find hot coffee harsh on the stomach often get on with cold brew.
Coarse grind, and why
A sixteen-hour steep is an enormous amount of contact time. Fine grounds have far more surface area and will over-extract even at low temperature, pulling out the bitterness the method exists to avoid.
Coarse grounds — visibly chunky, like raw sugar — extract slowly and evenly across those hours.
They also filter out. Fine grounds pass through a sieve and clog paper filters, and you will spend an hour waiting for a litre to drip through.
Do not agitate it
Stir once at the start so everything is wet, then leave it completely alone.
Stirring during the steep speeds extraction unpredictably and unevenly, and increases the bitter fraction. This is the opposite of most brewing methods and it is worth resisting the urge.
Room temperature or fridge
Room temperature for 12 to 16 hours gives a fuller, heavier body. The fridge for 18 to 24 hours gives a cleaner, more delicate cup. Both are valid and it is worth trying each.
Beyond about 24 hours you gain little and start to pick up staleness.
The ratio
100 g of coffee to 1 litre of water gives a concentrate roughly twice the strength of drip. Diluting one to one over ice is the standard serve.
If you want a ready-to-drink brew instead, halve the coffee to 50 g and skip the dilution.
Nutrition
Essentially nothing before milk goes in — around 15 calories a glass.
Caffeine content is often assumed to be lower because it tastes gentler. It is usually higher per volume, because the concentrate is strong. Dilute it properly and treat a glass as roughly one strong coffee.
It keeps for a week sealed in the fridge, which is the real argument for making it.
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