Nitro cold brew
Nitro cold brew is a cold brew charged with nitrogen and drawn from a tap like an Irish stout, with its cascade of bubbles and its tight head of foam. The gas barely changes what is in the cup; it changes the way it is drunk.
What does nitrogen do to a cold coffee?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
It starts from a cold brew, diluted or not, poured into a sealed keg: the liquid is ready in advance, in volume, like a beer. The pioneers improvised with home-brewer kegs and a simple regulator.
Read the stages without animation
- A cold brew in a kegIt starts from a cold brew, diluted or not, poured into a sealed keg: the liquid is ready in advance, in volume, like a beer. The pioneers improvised with home-brewer kegs and a simple regulator.
- Nitrogen under pressureThe keg is charged with nitrogen under pressure. This gas dissolves poorly, but it does dissolve, and does not sting. Carbon dioxide, by contrast, dissolves well and makes the water acidic: in a black coffee, it makes the drink almost undrinkable, hence the choice of pure nitrogen.
- The narrow faucetOn draw, a stout faucet forces the liquid through tiny holes: the dissolved gas comes out all at once, in very fine bubbles.
- The cascadeThe bubbles go down along the glass, then rise to form the head: the glass clouds up before clearing from the bottom.
- The head of foamA tight foam settles on the coffee. The small nitrogenous molecules of the brew make it foam, the polysaccharides, long chains of sugars, hold it. At Guelph, 70 mL of brew run through with nitrogen for 30 seconds make a head of 30 to 40 mL, more stable on a dark, very cold coffee, at 4 °C rather than 20 or 35 °C.
To remember: Nitrogen barely changes what is in the cup: dissolved under pressure, released as very fine bubbles at the tap, it changes the way the coffee is drunk.
In history: Nitrogen entered brewing in the 1950s; a roaster in Austin dates the first glass of nitro cold brew served to the public to the summer of 2012.
Read the full article and its sources ↓History
The idea comes from brewing. Nitrogen appeared there in the 1950s, at Guinness, when Michael Ash was seeking to extend the shelf life of beer, and an Irish stout faucet still serves a mix of three quarters nitrogen to one quarter carbon dioxide (source 3). “Nitro,” as American counters call it, is short for “nitro cold brew”: the same idea applied to cold-brewed coffee.
Mike McKim, founder of Cuvee Coffee in Austin, tells of having his lightbulb moment in 2011, drinking a lactose stout from the Left Hand brewery and watching its cascade of nitrogen; he called the brewery the next day and began charging kegs of cold brew with nitrogen (sources 2 and 3). The roaster dates the first glass served to the public to the summer of 2012 (source 1). Paternity is disputed even within the house: Lorenzo Perkins, who joined Cuvee in 2012, claims to be the first to have made and served it, and the two men agree on only one point, the public baptism at the Slow Food Quiz Bowl in Austin (source 3).
What followed was a spread through a network. Stumptown put nitrogen taps in its Portland cafés in June 2013 and canned its coffee in 2015; Starbucks announced more than 500 outlets equipped at the end of summer 2016 (source 4). Cuvee canned its own in 2014, with a nitrogen capsule housed in the can, and its can maker celebrated the launch with a billboard in Times Square (source 3).
The can has its risks. In 2017, Death Wish Coffee withdrew its nitro cold brew after consulting Cornell University's process authority: a low-acid liquid, deprived of oxygen by nitrogen, can allow the botulism bacterium to develop if the process does not prevent it (source 7). No poisoning had been reported (source 7).
The motion
It starts from a cold brew, diluted or not. It is put in a keg, charged with nitrogen under pressure, and served through a stout faucet that forces the liquid through small holes: the dissolved gas comes out as tiny bubbles, which cascade down the glass before rising to form the head. The pioneers improvised with home-brewer kegs and a simple regulator (source 3).
Why nitrogen alone? Carbon dioxide dissolves well and makes the water acidic; in a beer, the sugars offset it, in a black coffee it makes the drink almost undrinkable. Stumptown's brewmaster says it “strips” the coffee of its sweetness, hence the choice of pure nitrogen; nitrogen dissolves poorly and does not sting (source 3).
The settings
- Grindthat of the original cold brew; a finer grind gives a more stable foam (source 5)
- Dosethat of the original cold brew; the coffee-to-water ratio matters little for the foam, between 1:5 and 1:15 (source 5)
- Brew ratio1:5 to 1:15 in the Guelph trials (source 5)
- Temperatureserved cold; the foam holds better at 4 °C than at 20 or 35 °C (source 5)
- Timenot documented in the sources read
- Pressurekeg charge pressure not documented in the sources read; pure nitrogen, no carbon dioxide (source 3)
What it has going for it
- Nitrogen gives a softer texture and a richer, creamier impression, according to a draft equipment supplier (source 3).
- Unlike carbon dioxide, it adds neither sting nor acidity, which leaves the coffee its sweetness (source 3).
- The coffee is served from the tap, from a keg prepared in advance, like a beer: this is what allowed its spread to hundreds of shops (source 4).
- The cascade and the head of foam make a show at the counter, the one that had won over McKim in front of his beer (source 2).
What is held against it
- A keg, a gas bottle, a regulator and a special faucet are needed: brewer's equipment, not kitchen equipment (source 3).
- Not all coffees suit it: a very bright, fruity coffee risks losing what one loved in it, warns the same supplier (source 3).
- The foam holds less well on light roasts, the ones chosen for their delicate aromas (source 5).
- In cans, the absence of oxygen and the low acidity require a process validated against botulism; two recalls have reminded us of it, in 2017 and in 2024 (sources 7 and 8).
What it gives in the cup
What nitrogen brings is measured mostly in the foam. At the University of Guelph, 70 mL of cold brew run through with nitrogen for 30 seconds make a head of 30 to 40 mL. At equal roast, arabica gives a more stable foam than canephora; stability rises with roast degree, brewing temperature and grind fineness, and when the drink is colder (source 5). The small nitrogenous molecules of the brew make it foam, the polysaccharides, long chains of sugars, hold the foam (sources 5 and 9).
The thesis that accompanies the study puts figures on the gap between roasts: the dark brew is a little more viscous, 1.150 against 1.110 millipascal-second, and sweeter, 6.78 against 6.29 mg of total sugars per milliliter, which explains its longer-lasting foam (source 6). For the rest, the cup is that of the starting cold brew, texture aside.
Anecdotes
- McKim's lightbulb moment came from a bottle of lactose beer that had to be poured all at once into the glass, the label said, to see the cascade (source 3).
- Lorenzo Perkins says he asked his boss for payment for the nitro cold brew idea: “He laughed. I left.” (source 3).
The sources for this sheet
- Cuvee Coffee, “The Origins of Nitro Coffee,” cuveecoffee.com, September 23, 2018 · online · manufacturer
- “Cuvée Coffee's Nitro Cold Brew is Kind of Exploding Right Now,” Daily Coffee News, December 16, 2015 · online · press
- “Rising to the Top: How Nitro Transformed Beer and Coffee,” Good Beer Hunting, July 2019 · online · press
- Daniela Galarza, “Starbucks introduces nitro coffee,” CNBC, May 31, 2016 · online · press
- Dongning Yu, Xiuju Wang and Loong-Tak Lim, “Investigation of the factors affecting foamability and foam stability of cold brew coffee,” Journal of the Science of Food and Agriculture, 102 (13), 5875-5882, 2022 · online · primary · reading: article abstract (AGRIS record)
- Dongning Yu, “Foaming properties of cold brew coffee,” master's thesis, University of Guelph, defense abstract · online · primary · reading: defense abstract
- “Death Wish Coffee pulls ‘Nitro’ because of botulism risk,” Food Safety News, September 21, 2017 · online · press
- Nick Brown, “Snapchill Recalls All Cold Brew Cans Due to Toxic Growth Risk,” Daily Coffee News, June 19, 2024 · online · press
- S. P. Ishwarya and P. Nisha, “Unraveling the science of coffee foam: a comprehensive review,” Critical Reviews in Food Science and Nutrition, 61 (10), 1704-1724, 2021 · online · secondary · reading: article abstract