How to Make Nitro Cold Brew: Keg, Nitrogen and Stout Faucet
How to make nitro cold brew: drinking-strength cold brew, pure nitrogen, charging a keg through a diffusion stone or using an inline infuser, serving pressures, the stout faucet and troubleshooting.
In this post
The short answer: make cold brew at drinking strength, chill it to 34 to 38°F, put it in a keg, and push it with pure nitrogen through a stout faucet, either after charging the keg with nitrogen through a diffusion stone or through an inline nitro infuser. The nitrogen makes the tiny bubbles, the creamy cascade and the thick head.
Nitro cold brew is ordinary cold brew served like a stout. Nitrogen barely dissolves in liquid, about 80 times less than CO₂, so it does not make coffee fizzy or sour. It comes out of solution as the coffee is forced through the small holes of a stout faucet, and that is the cascade.
What you need
- Cold brew at drinking strength, about 1:12, or concentrate diluted 1:1. See cold brew ratios.
- A keg and a fridge or kegerator that holds 34 to 38°F.
- Pure nitrogen, from a cylinder or a nitrogen generator, with a nitrogen regulator. Not beer gas: its 25% CO₂ slowly carbonates the coffee and sours it.
- A stout faucet with a restrictor plate, or an inline nitro infuser in the line to a faucet.
Two ways to add the nitrogen
| Charge the keg | Inline infuser | |
|---|---|---|
| How | Nitrogen through a 0.5 micron diffusion stone in the keg, then rest it cold | Still cold brew flows through an infuser that adds nitrogen on the way to the tap |
| Pressure | About 30 to 40 psi to charge and serve | About 30 to 40 psi of nitrogen to the infuser |
| Time | 24 to 48 hours in the cold before it pours well | Pours right away |
| Best for | One or two kegs, home and small cafés | Busy cafés and several taps |
Step by step: charging a keg
- Brew and filter the cold brew, and chill it to 34 to 38°F before it goes in the keg.
- Fill the keg, leaving a few inches of headspace, and seal it.
- Purge the headspace with nitrogen two or three times to push out the air.
- Set the nitrogen regulator to about 30 to 40 psi and leave it connected. A keg lid with a diffusion stone spreads the gas into the coffee faster.
- Rest the keg cold for 24 to 48 hours.
- Pour through a stout faucet, wide open, into a clean glass. Let it settle for a few seconds and watch the cascade.
Troubleshooting
| Problem | Cause | Fix |
|---|---|---|
| No cascade, thin head | Too warm, too little pressure, or a standard faucet | Serve at 34–38°F, through a stout faucet, at 30–40 psi |
| Sour or prickly | Beer gas or CO₂ in the keg | Pure nitrogen only; purge and refill |
| Sputters and spits | Keg nearly empty, or the regulator set too high | Swap the keg; lower the pressure in small steps |
| Stale, flat flavour | Old cold brew, or air in the keg | Keg it fresh and purge with nitrogen |
Frequently asked questions
Can I use CO₂ instead of nitrogen?
Not for nitro. CO₂ dissolves easily and makes coffee fizzy and sharper. It is a different drink: sparkling cold brew.
Do I need a stout faucet?
Yes, or an infuser with its own nitro faucet. A standard beer faucet pours it flat.
How long does nitro cold brew keep in the keg?
It is cold brew, so the same rule applies: kept at 41°F or colder, about a week. Cold brew is a low-acid drink; treat it as a perishable.
Can I charge nitrogen in a fermenter?
Do it in kegs. Nitro charging runs around 30 to 40 psi or more, above what most fermenters are rated for; our Unitanks are rated to 30 psi.
Making the cold brew
The nitro is the easy part; consistent cold brew is the work. A Unibräu steeps the coffee in a lift-out basket, recirculates it through the coffee bed with its pump for a clearer brew, drains through a tri-clamp valve, and chills it on the way to the keg through a counterflow chiller. See the cold brew system.