Cold Brew

Cold brew is not iced coffee. Iced coffee is hot-brewed coffee poured over ice. Cold brew is coffee brewed with cold or room-temperature water from the start, steeped for many hours, then filtered. The absence of heat changes everything about the extraction: different compounds dissolve, the flavour profile shifts dramatically, and the result can be stored for 1–2 weeks in the refrigerator.

Why Cold Water Changes Extraction

Hot water extracts coffee's soluble compounds quickly and indiscriminately. Cold water extracts more slowly and selectively. The organic acids responsible for brightness — citric, malic, acetic — extract far less readily at low temperatures. The result is a cup that is noticeably lower in perceived acidity and higher in perceived sweetness, even without any sugar. The sugars and longer-chain compounds that contribute body extract more easily relative to the acids, producing a rounder, heavier mouthfeel.

The tradeoff is time. What a V60 does in 3 minutes with 93°C water takes 12–24 hours at room temperature, and longer in a refrigerator (where temperatures of 3–5°C slow extraction further).

Ratios

Cold brew is typically brewed as a concentrate, then diluted before serving:

• Concentrate ratio: 1:5 to 1:8 (coffee to water by weight). A 1:5 ratio produces a strong concentrate that is usually diluted 1:1 with water or milk before drinking.
• Ready-to-drink ratio: 1:12 to 1:15. This produces a cold brew you can drink directly without dilution, with a strength comparable to drip coffee.

Starting with concentrate gives flexibility and reduces fridge space. Brew at 1:5, store the concentrate, and dilute to taste each time.

Steep Time and Temperature

• Room temperature (18–22°C): 12–16 hours. Faster extraction; slightly brighter flavour due to more even extraction of all compounds.
• Refrigerator (3–5°C): 18–24 hours. Slower, more selective extraction; often even lower acidity; more controlled if you are batch brewing for storage.

Steeping longer does not indefinitely improve the brew. Beyond 24 hours, off-flavours from over-extraction begin to emerge — unpleasant bitterness, a flat, hollow character. Stick to the recommended window.

Grind Size

Use a coarse grind — coarser than French press. Cold water has low penetrating power, and finer grounds compact during the long steep, restrict water flow during filtration, and produce over-extracted, astringent results. Coarser grounds allow full water contact and easy filtering without the brew turning muddy.

Filtration

After steeping, the grounds must be filtered out. Options:

• Paper filter: Produces the cleanest, most transparent cold brew.
• Metal filter: Leaves more fine particles and oils, adding body (similar to the French press effect).
• Cheesecloth or cloth filter: A middle ground; removes larger grounds but allows more oils through than paper.

Filter slowly. Do not press or squeeze — pressure forces fines through the filter and makes the cold brew hazy and bitter.

Roast Selection

Cold brew tolerates and often benefits from medium to medium-dark roasts. The low-acid extraction profile works well with roasts that have caramel, chocolate, and nut notes. Light roasts brewed cold can taste thin and under-sweet because the fruity, floral compounds that make them attractive at hot temperatures extract poorly in cold water. If you want to cold brew a light roast, extend steep time slightly and brew at room temperature rather than in the refrigerator.

Nitrogen Cold Brew

Nitro cold brew is cold brew infused with nitrogen gas and dispensed on tap, like draught beer. Nitrogen produces smaller, more stable bubbles than CO2, creating a creamy, cascading texture and a thick, velvety foam head. The nitrogen itself has no flavour, but the texture amplifies perceived sweetness and body. It is served without ice because chilling is built into the dispense system.

Storage

Cold brew concentrate keeps well in the refrigerator for up to 2 weeks. Once diluted, drink it within 3–4 days. The concentrate's lower water activity and the extraction process itself mean it has lower bacterial activity than hot-brewed coffee, contributing to its longer shelf life.