Split Key Coffee
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Split Key Coffee

Homemade Nitro Cold Brew

It’s summer time here on the east coast and that means it’s time for cold-brew coffee! In the past, I’ve made a few small batches from my personal roasts, but I thought it could be fun this year to dive into something new…nitro! Nitro cold-brew is one of my favorite ways to enjoy coffee, but I’ve always been too intimidated to try it at home. Turns out, making my own batch wasn’t difficult at all! In this post, I am going to walk through my process in making nitro cold-brew at home.

This is the 3rd batch of nitro cold-brew I’ve made at home with my last batch being a naturally processed Brazilian bean––one having more chocolate and nutty flavors. For this batch, I roasted 400 grams of naturally processed Burundi Agahore Station which tends to have more wine and jam-based flavor notes. With this batch, I tried to keep the roast levels the same (medium), so I could compare the overall taste between each bean.

Post-roasting, 400 grams turned into 347 grams due to moisture loss. For this coffee, I’ve found that it benefits from resting for 4 days prior to brewing.

For drip coffee (pour-over, french press or cold-brew), I use a Nuova Simonelli Grinta grinder and grind directly into a nylon bag. I’ve found the bag to be extremely helpful once the grounds are introduced to the water. It saves me one less filtration step for when I move the coffee to the keg later.

One of the biggest benefits to grinding so much coffee at once is that the whole basement takes on a fresh coffee smell. This Burundi puts off a beautiful sweet scent that reminds me of Trix cereal and fresh-baked shortbread cookies.

I use a 5 gallon bucket for steeping and fill it will Poland Springs water. I use Poland Springs in my espresso machine to reduce internal mineral build-up and now also enjoy it for all my other brewing. For this batch, I am using a 13:1 ratio which yields 1.25 gallons of cold-brew. Unlike other recipes, I prefer to avoid the concentrate approach as it can get complicated mixing ratios post brew.

The nylon bag filled with coffee grounds is added to the bucket and covered for 18 hours. I haven’t played around with overall steep times too much, though generally find the 16–18 hour steep to work well.

After the long steep, there’s a noticeable change in the overall color as the coffee has made it’s way into the water. Just on smell alone, I could tell this roast came out as I wanted––there was a strong jammy sweetness to the coffee that was very-much what I am used to when brewing hot.

With the grounds removed from the coffee, it’s time to transfer over to the keg. I ended up going with a smaller keg (2.5g) since it’s rare, if ever, that I will brew more than that at any given time. From past experiments, I’ve found the cold-brew coffee to have a 2–3 week shelf-life before it starts to degrade in quality. I use a mesh filter when pouring the coffee into the keg just to be safe, it doesn’t really filter the coffee itself (nylon bag for the win).

Pro-tip if you ever decide to follow along and make your own nitro cold-brew––there’s always a very fine sludge of coffee at the end of your pour that should not make it’s way into the keg. If the sludge gets into the keg, it’s likely to run through your output lines and clog your taps when serving.

With the coffee in the keg, I move onto the last stage of the process, infusing the nitrogen. I ended up going with a Quick Cascade Lid for my keg which includes an input feed line that filters using a diffusion stone. Having this lid just helps speed up the infusion process, though it’s not a requirement.

This is where I always felt intimidated––something about highly pressurized gas freaks me out. My fears were misplaced as hooking up the nitrogen was super easy, I just had to follow a few steps. I start with a cold canister (left in my fridge) and hook the hose line into the “in” feed for the keg. Before unscrewing the nitrogen, I check my flow valve to ensure it’s closed and that my regulator screw is all the way out (no pressure).

Once unscrewed, the left gauge will give me a read out of the remaining gas I have left in the canister. From there, I open the flow value to the keg.

Using a screwdriver, I slowly bring the keg to pressure by turning the pressure screw until I get to 45%. I will pause at each 10% increment and wait a minute before increasing. During the process, I will pull the release on the keg lid a few times just to purge any oxygen in the keg (since I don’t do full batches).

And that’s all there is to it! After several hours have passed, the cold-brew is ready to enjoy. While it can be enjoyed almost immediately, I find that it is best to wait 24–48 hours for good results and 3–4 days for the best results.

You know you have a good result when you see a lot of cascading in the coffee. As it settles, you should see a nice billowing effect take place as a foam head appears at the top of the cup. Cold-brew coffee alone is extremely smooth and shouldn’t have much acidity. Adding nitrogen to that output only increases the creaminess of the coffee and gives it much more body. For hot summer days, there’s no better way to enjoy coffee in my opinion.

I linked to the materials I used throughout the post, but here’s a quick reference just in case you want to replicate elements of this at home.

For the nitrogen canister, you can go to a local oxygen store to get one of these. Tanks run about $90–100 and are exchanged each time you need a full one. A fill ends up running around $40–50 dollars.

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Interested in highlighting great coffee, baristas, shops and roasts. Always seeking to learn more about the craft. 🗝️ ☕️

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Brandon Dixon

Brandon Dixon

Founder of @BlockadeIO, PDF X-RAY, and @PassiveTotal. Partner and developer for @TheNinjaJobs. VP of Strategy for @RiskIQ. Roaster at @SplitKeyCoffee.

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