Cold brew coffee keg, nitro coffee and espresso martini kegs

So by now you’ve probably seen “cold drip” or “cold brew” coffee popping up in your local cafes. And now the latest craze of “nitro coffee” So what are they and why should you care?

They are all virtually the same thing made slightly different ways with the sole purpose of making a cold coffee that is smooth and flavourful enough to drink without milk, cream, sugar etc.

The usual way till recently of getting a cold coffee has been to pour a shot of espresso over ice. This has two major downfalls.

Espresso is made by pushing blistering hot steam and water through finely ground roasted coffee beans. It is by far the most “violent” method of extracting the flavour from beans and the steam pulls with it many bitter and acidic flavours.

Because the boiling hot coffee is poured onto ice to chill it is instantly diluted as the ice melts.

Cold brew or drip coffee on the other hand is made as it sounds.

It is a much gentler extraction using course coffee grounds steeped in cold water for generally 12-24 hours (or cold water is dripped over them for a similar amount of time).

This results in a coffee with a much lower level of acidity and bitterness that is naturally sweeter and because it’s already cold when poured over ice it isn’t instantly diluted as the ice doesn’t melt immediately.

Cold brewing is generally regarded as a much better method of producing cold coffee for these reasons.

To make it yourself at home there is only 3 easy steps and you probably have everything you need already:

1. Brew: Just combine 1 part course ground coffee (you can use fine ground but it will produce a cloudier brew and be more difficult to strain all the grounds out) with approximately 8 parts water in a clean container and let it sit at least overnight. Any jug, jar, pot or bottle will do!
2. Strain: Get rid of a large proportion of the grounds 1^st by just using a sieve then pour through the sieve with paper towel or a coffee filter a couple of times till there is no sediment left at the bottom of your container. You can even use your coffee plunger to do small batches.
3. Serve: Drink as is, on ice or with milk if you are boring…

So you now have your homemade cold brew coffee but what is this nitro coffee business? I hear you say….

For a long time beer drinkers have loved using nitrogen or a mix of nitrogen and carbon dioxide for pouring stouts. It is what gives Guinness that beautiful cascading foam and creamy mouth-feel. This effect is created by using a stout tap, these have a long slender spout and work by forcing the beer through a restrictor plate (consisting of a plate with a few small holes drilled in it) inside them.

Normally beer is stored in a keg with a source of CO2 connected at about 10-12psi. Any more pressure than that would dissolve more CO2 than wanted into the beer making it an over-carbonated foamy mess when you poured it. To force the beer through that fine sieve though a much higher pressure of around 30-40psi is needed. This is where nitrogen comes in because, unlike CO2, nitrogen (N2) doesn’t dissolve very well into liquid. In fact at 5 deg C (normal serving temperature) CO2 is about 100x more soluble than nitrogen. Meaning we can store it a high pressure without further carbonating the beverage.

If you were to use CO2 in your coffee keg it would become carbonated over time undoing all that work you put in to make it. Carbonation adds an acidity and sharper mouth-feel to a drink whereas what we are aiming for is a smooth and rich flavour.

Therefore, nitrogen is great for storing and serving coffee!

If you were to put your coffee into a mini keg (or full size keg if you are a café, restaurant or bar owner) and flush it out with nitrogen your coffee is protected from oxygen that will cause it to go stale or off. You can then store it in the fridge for weeks!

If you want a beautiful creamy cold brew that looks like a Guinness without needing any milk you can crank up the pressure, put on a stout tap and pour something like these little beauties!