Cold Brew

What Is Cold Brew?

Cold brew coffee — also called cold water extraction or cold pressing — is prepared by steeping coarsely ground coffee beans in water at cool or room temperature for an extended period, typically 12 to 24 hours [S1]. The grounds are then filtered out through a paper filter, a fine metal sieve (as in a French press), or felt cloth, leaving behind a coffee concentrate that is commonly diluted with water or milk before serving.

Unlike every other mainstream brewing method, cold brew never exposes the grounds to heated water. This single difference drives most of its distinctive sensory and chemical properties. The resulting beverage can be served chilled over ice, blended with ice and other ingredients such as chocolate, or even gently warmed — though cold service is by far the most common presentation.

History and Origins

Cold brew has deep historical roots. According to documented accounts, the Dutch introduced cold-extraction coffee to Japan, where it became an established brewing tradition over several centuries [S1]. The slow-drip variant — in which water is dripped through coffee grounds at room temperature over many hours — became known as "Kyoto-style" coffee, or in broader East Asian usage, "Dutch coffee" [S1].

The contemporary commercial revival of cold brew in Western markets gathered momentum alongside the third-wave coffee movement, as specialty roasters sought to highlight origin sweetness and reduce bitterness without relying on milk or sugar.

The Chemistry of Cold Extraction

Because the grounds never contact heated water, cold brew produces a chemically distinct profile compared with hot-brewed coffee [S1]. Several key principles govern what ends up in the cup:

• Temperature and solubility: Coffee beans contain compounds — including caffeine, certain oils, and fatty acids — that are more soluble at higher temperatures. Cold extraction therefore draws a different subset of those compounds into solution over its long contact time [S1].
• Caffeine: Counterintuitively, brewing at lower temperature for 24 hours results in higher caffeine content per equal volume compared with approximately 6 minutes at 98 °C (208 °F) [S1]. This effect is amplified by the high coffee-to-water ratio used when making concentrate.
• Acidity: The pH of cold brew and hot brew coffee is broadly similar, but cold brew has a lower titratable acid concentration — meaning fewer total dissolved acids — which is why it tastes perceptibly less sharp. Both pH and titratable acidity influence the sensory experience of acidity [S1].
• Bitterness: Heat-sensitive bitter compounds extract at lower rates in cold water, contributing to cold brew's characteristically smooth, rounded flavor.

Understanding these dynamics connects directly to the principles covered in Extraction: Yield & Strength.

Grind Size

A coarse grind is standard for cold brew [S1], and this is not arbitrary. As explained in Grinding & Particle Size, brewing methods with longer water-contact times require coarser particles to avoid over-extraction. Applying a fine grind to a 12–24 hour steep would expose far too much surface area, producing harsh, bitter, and astringent results, as well as slowing or clogging filtration [S2].

A burr grinder is strongly preferred over a blade chopper: burr mills produce a more uniform particle distribution, which means more even extraction across the entire bed of grounds [S2]. For a coarse cold-brew setting, aim for a consistency resembling coarse sea salt or raw turbinado sugar.

Brew Ratio and Dilution

Cold brew is almost always prepared as a concentrate, brewed at a much higher coffee-to-water ratio than a standard hot cup. General brew ratios for hot methods commonly fall in the range of 15–18:1 water to coffee by mass [S2][S3]; cold brew concentrates are typically prepared at ratios closer to 4:1 to 8:1 (water to coffee), with the expectation that the concentrate will be diluted 1:1 or more at serving time.

Key considerations for ratio and dilution:

• Higher coffee dose → stronger concentrate, higher caffeine, more body when diluted.
• Dilution medium matters: water keeps flavors cleanest; milk or a plant-based alternative adds body and mutes acidity and aroma [S2][S3].
• Brewing a concentrate rather than a ready-to-drink brew also improves storage efficiency — a smaller volume stores longer without degrading.

For a deeper treatment of ratio variables, see Brew Ratio.

Cold Brew vs. Iced (Flash) Brew

These two methods are frequently confused but are fundamentally different:

Flash brew (also called Japanese iced coffee) brews hot coffee directly onto ice — capturing volatile aromatic compounds that cold extraction largely cannot, because those aromatics are released by heat [S2][S3]. The trade-off is a brighter, more acidic cup. For those who prize the floral and citrus notes of a light-roast origin coffee, flash brew often outperforms cold brew. Equipment such as the Hario Switch is well suited to flash-brew immersion technique.

Cold brew, by contrast, excels with medium to dark roasts whose chocolate, caramel, and nutty notes translate well through the low-acid, low-temperature process.

Nitro Cold Brew

Nitro cold brew is cold brew charged with nitrogen gas, dispensed from a nitrogen beer-tap system [S1]. The dissolved nitrogen creates a cascade of fine bubbles and a rich, creamy foam head — visually and texturally similar to a draft nitrogenated stout.

• Nitro cold brew is served without ice, which would destroy the foam head [S1].
• The nitrogen gives the beverage a smoother, creamier mouthfeel without adding dairy or sugar.
• Its commercial origins are disputed, but it was first offered at third-wave coffee shops in the early 2010s [S1]. Possible origins include Cuvee Coffee in Austin, Texas and Stumptown in Portland, Oregon, around 2012–2013 [S1].
• By 2016, Starbucks was rolling out nitro cold brew at 500 stores, and by 2020 it was available at more than half of Starbucks US locations [S1].
• Canned nitro cold brew — using a nitrogen-filled capsule to pressurize the can — became commercially available from Stumptown and Cuvee by 2015 [S1].

The nitrogen used is the same gas occasionally employed in darker stouts such as Guinness, specifically chosen because — unlike carbon dioxide — it produces a smoother, less sharp carbonation [S1].

Food Safety and Storage

Because cold brew operates at low temperatures for extended periods, food-safety discipline is essential:

• Steep in the refrigerator when possible for the full brew period, particularly in warm climates. Room-temperature steeping is common and generally safe for a 12–24 hour window, but the finished concentrate should be refrigerated immediately after filtering.
• Filtered concentrate should be stored in a sealed glass or food-safe container in the refrigerator. It is widely recommended to consume cold brew concentrate within 1–2 weeks of brewing; ready-to-drink (diluted) cold brew should be consumed within a few days.
• Cold brew stores well because it maintains its character cold better than hot-brewed coffee — the absence of volatile aromatic compounds that degrade quickly actually works in its favor for shelf life [S2][S3].
• Equipment hygiene: Any vessel, filter, or tap system used for cold brew should be thoroughly cleaned between batches. Residual coffee oils can turn rancid and harbor bacterial growth, particularly in the warmer parts of a room-temperature steep.
• For nitro cold brew served from a keg or tap system, follow the same sanitation protocols used in draft beer service.

Brewing Step-by-Step

1. Grind coarsely. Use a burr grinder set to a coarse setting — approximately the texture of coarse sea salt.
2. Combine coffee and water. Use a coffee-to-water ratio suited to your target concentration (e.g., roughly 1 part coffee to 4–8 parts water by mass). Water for Coffee quality applies here: filtered, low-mineral water is a common recommendation.
3. Steep. Cover and steep for 12 to 24 hours at room temperature or in the refrigerator [S1]. Longer steeps and room-temperature steeps generally extract more.
4. Filter. Pour through a paper filter, fine metal sieve, or felt filter to remove all grounds. Double-filtering (metal sieve then paper) produces a cleaner cup.
5. Dilute and serve. Dilute concentrate to taste — a 1:1 ratio with cold water or milk is a common starting point — and serve over ice or chilled.
6. Store. Refrigerate the concentrate in a sealed container and use within one to two weeks.