Nitro Cold Brew. Even though this cold coffee has been in for a few years already, it is still veiled in mystery. Where does it come from before it gets to the tap? What makes it so beautiful and what makes its texture so smooth?
What is nitro?
Nitro Cold Brew, commonly shortened to Nitro, is the name of coffee infused with nitrogen. The idea, wild as it seems, is in itself not a new one – the same principle applies to tap aerators or the famous Guinness beer which we will discuss a bit later. Nitrogen is dispensed from a tank into the keg of coffee in a way similar to that used in brewing beer. Guinness, its famous foam and unique texture are precisely the result of adding nitrogen. This is exactly what a nitro brewing process is all about. Nitrogen somewhat squizes into the coffee structure, giving it a smoth and thick body. Nitro reveals flavour notes usually absent from cold brews; repeatedly, we succeeded in brewing batches tasting of cognac, red wine or even pineapple juice.
Indispensable parts of nitro are precisely the foam and ”cascading effect” which we owe to the tap structure. Inside the tap neck, there is a small valve with tiny holes hit by the pressurised nitrogenated coffee. When coffee passes through the holes, it and the gas contained in it get agitated, creating the impressive effect of the brew. And yet, the foam is there not only for a showoff; it also makes nitro appear sweeter (as a result of a mysterious illusion playing with our taste buds). What will most certainly make coffee geeks happy is the fact that nitrogen help us absorb caffeine contained in coffee. Even a small 100 ml cup of nitro gives you a caffeine kick compared to a 200 ml drip.
Nitro coffee is always served cold; first, it tastes better this way, second, this is required by the chemical reaction between nitrogen and coffee.
How to start?
To start making nitro two things are essential: nitro equipment and coffee. Let’s start with the first one. You will need a keg, nitrogen tank, regulator, fridge and tap. Even though each of these components is manufactured specifically for baristas, you can just as well build your set-up from parts used for beer brewing. The most important thing is to remember the two key differences between a coffee and a beer tap:
1. Nitro (as the name suggests) should be infused only with pure nitrogen, no nitrogen and carbon dioxide mixtures, which could spoil the taste of coffee.
2. To achieve a full visual effect, you should use the Guinness/nitro stout tap. Its structure makes for the lion’s share of nitro’s beauty.
Now let’s talk about coffee. Technically speaking, you can brew nitro with every coffee type, however, the most practical and sensible way to brew it is with cold brew. We usually make twenty litre batches with this type of coffee. When the coffee is ready, it can either be nitrogenated, bottled or drunk as a classic cold brew. Its strength should be matched to your taste, but we stand by the ratio of 60g of coffee to 1 litre of water.
Only cold brew?
Having said that, cold brew is not the only way of making nitro. We tested cold drip, but it couldn’t satisfy the growing demand (which has risen proportionally to the temperature outside). Some coffee shops brew their nitro from batch brew, which makes for an interesting flavour and helps control the extraction. Freshly brewed coffee needs cooling, as nitrogen is absorbed best in low temperatures. When the coffee is already inside the keg, we dispense nitrogen two times. The first time, it is needed to get rid of the oxygen (which would speed up the process of coffee spoilage).
Once the nitrogen has filled up the keg, the magic begins. Gas particles slowly infiltrate the liquid, which can take up to 24 hours. Patience pays off: once the nitrogen has helped the coffee ”mount” to the tap, your cup gets filled with a drink entirely different in texture.
Probably there are many other ways of making a delicious nitro and the end product depends on your imagination. Coffee is just the beginning – you can nitrogenate and tap also cascara, tea and any other drink you can think of. So all we can do now is wait for the first Nitro Multitap Bar! If you still can’t get your head around nitro, go out and try it yourself. As far as in know, in Warsaw you can get nitrogen-infused coffee, in, i.a., Coffeedesk, Cophia, Czytelnia, Kawiarnia Kawałek and Tłusty Kotek