Cold brew steeping

Why cold extraction tastes different

CoffeeHQ explanation

Different compounds in coffee dissolve at different rates, and temperature affects them unequally. Cold water extracts everything slowly, and some of the compounds responsible for sharp acidity and for bitterness come out much less readily than they do in hot water. A long steep makes up the strength without bringing all of them along.

The trade is aroma. Many of the volatile compounds that make hot coffee smell vivid are released by heat and never make it into a cold brew in the same way. So cold brew is rounder and gentler and also plainer, and coffees prized for delicate floral or fruity notes usually show less of them.

Concentrate or ready-to-drink: decide first

Typical range

There are two ways to make cold brew, and the ratio depends entirely on which you choose. Neither is the correct one.

Cold brew recipes vary more than those for any other method. These ranges describe common practice; there is no standard ratio, and strength is a matter of preference.

Making a batch

CoffeeHQ explanation

1. Combine coarse coffee and cold water. Use a jar, a jug or a French press. Stir until every particle is wet; dry pockets in the middle of the mass will not extract.
2. Cover and leave it. Steep for twelve to eighteen hours. In the fridge, lean towards the longer end. Start with sixteen hours and adjust the next batch by taste.
3. Filter in two stages. Strain through a sieve or the press's mesh first to remove the bulk, then through paper or cloth for a clear result. Trying to do it in one pass through paper clogs quickly.
4. Label it and refrigerate. Note whether it is concentrate or ready-to-drink and the date. Keep it sealed in the fridge.

Diluting concentrate

CoffeeHQ explanation

Dilution is simple arithmetic: equal parts concentrate and water halves the strength. A concentrate brewed at around 1:8, diluted one to one, lands close to ordinary drinking strength, and that is a sensible first attempt. Adjust the dilution, not the batch, until it tastes right.

Remember that ice is water too. If the drink will sit over ice, dilute a little less than you would for a drink served straight, or the last third of the glass will be thin. Milk dilutes in the same way water does while adding sweetness and body.

Keeping it

CoffeeHQ explanation

Cold brew has had no heat step, so treat it as you would any other perishable drink: make it in clean equipment, keep it refrigerated and do not leave it standing at room temperature once it is filtered. Flavour is usually the first thing to go, fading and flattening over several days.

Concentrate holds its character longer than diluted brew. If a batch smells or tastes off, discard it. CoffeeHQ does not give a number of days here because it depends on how the batch was made and stored.

Fixing the next batch

Tendency, not a guarantee

Weak and watery

Usually because: Too little coffee, too much dilution, or melting ice. Less often, too short a steep.

Change first: Dilute less first, since that costs nothing. If the undiluted brew is weak, use more coffee in the next batch.

Work through cold brew strength

Bitter, woody or astringent

Usually because: Steeped too long, or ground too fine for a brew of this length.

Change first: Shorten the steep by a few hours. If you ground finer than coarse, go coarser instead.

Work through bitter coffee

Cloudy or silty

Usually because: Fine particles have passed the filter, usually from a single coarse straining.

Change first: Filter a second time through paper, and let the brew settle before pouring off.

Reduce sediment

Flat and lifeless

Usually because: The coffee was stale to begin with, or the batch has been kept too long. Cold brew starts with less aroma, so it has less to lose.

Change first: Use fresher coffee and make smaller batches more often.

Tell stale coffee from a brewing fault

Cold brew against other cold coffees

Tendency, not a guarantee

• Iced coffee — Brewed hot and then chilled or poured over ice. It keeps more acidity and aroma, and is ready in minutes rather than the next day.
• Nitro cold brew — Cold brew infused with nitrogen and served from a tap, which gives a creamy texture and a foamy head without any milk.
• Iced latte — Espresso with cold milk and ice. More intense in coffee flavour per sip and much quicker to make.

Where it comes from

Accounts differ

Slow cold extraction has a long association with Kyoto, Japan, where coffee is brewed by letting cold water drip through grounds over many hours. It is often said that Dutch traders introduced the idea, and the style is sometimes called Dutch coffee, but that account is repeated far more often than it is evidenced.

Steeped cold brew of the kind described here became widely popular much more recently, spreading through cafés and bottled products from the 2010s.

What to do next

• Cold-brew batch and dilution calculator — works out how much water or milk to add to a concentrate of a given strength.
• Cold brew vs. iced coffee — the two are routinely confused and are made in opposite ways.
• Extraction science: solubility and diffusion — the fuller explanation of why temperature changes which compounds end up in the cup.
• French press — the most convenient vessel for making cold brew at home, and the same immersion principle with heat.
• Become a barista — A structured programme from dose and grind through milk, drinks and maintenance.