Espresso Martini Keg | Recipe & Step-By-Step Instructions | iKegger

Espresso Martini Keg Recipe

For home use with our mini keg system. Our standard recipe makes approximately 14 martinis in our 2L keg. The number you get depends on how generously you pour them. The recipe leaves around 300ml of empty keg space. 

It is important to leave some empty space in the keg so there is plenty of surface area in contact between the liquid and gas. It also means shaking the keg mixes the ingredients well, as there is room for them to move.

You can increase or decrease the volume of mix you make depending on how big your keg is, and how much you want to make in a batch, but leave some empty space. Also be aware that if you have a lot of empty space in a keg you will use up gas bringing the empty space up to absorbing pressure.

Aborbing Nitrogen into liquid that can hold foam (eg coffee and beer) is what causes the iconic Guinness pour with cascading bubbles that form a dense head as it settles. This is why it is also perfect for pouring espresso martinis or nitro coffee.

Successful nitrogen infusion into espresso martini mix relies on 3 conditions:

 

Chilling The Espresso Martini Mix:

• Chill all the ingredients before putting them into the keg. This is doubly important using the insulated black kegs. The colder the liquid, the more nitrogen can absorb into it. If you start with room temperature liquid no gas will dissolve until it is down close to 0 deg so ideally put the vodka in the freezer and chill the rest.
• The black kegs are insulated and will stay cold all day out of the fridge. The same works in reverse, if you put room temperature liquid in and then put the keg in the fridge it will be at least 24 hours before it is cold and only then will it start absorbing gas. For absolute best practice, swirl some cold water around in the keg to chill it before filling with chilled ingredients.
• Our recipe calls for ice cubes to be put in the keg, this is an important part of the recipe so don't leave them out.

Absorbing:

• Always double check the regulator is turned off before screwing in or unscrewing a gas bulb and also before connecting or disconnecting the regulator from a keg, both result in a sudden change in gas pressure that can damage the regulator.
• Insert a bulb and connect the regulator to the keg filled with martini mix and ice cubes.
• Turn the pressure up to 50psi and shake the keg well for about 30 seconds. Shaking like a cocktail shaker where the liquid and ice smash backward and forward is more effective than the liquid swirling as it "beats" the gas into the liquid.
• If your martini mix is ice cold and the pressure is high enough, nitrogen will slowly absorb into the liquid just by leaving the keg in the fridge overnight with the regulator turned on, however it's not as effective as shaking.

Pouring:

• With more than 20psi of pressure in the keg it is harder to control the flow rate as you have to push quite hard on the button. It's also worth noting that the first time you press the button for each round of drinks it will require a little more pressure and may "stick" for a second then release, which the following pours won't do.
• Personally I turn the regulator off and then do a test pour into a tumbler or water glass to see if the foam is looking good, at the same time as reducing the pressure and "unsticking" the button. After that it's a lot easier to control the flow rate depending on how hard you push the button so you can pour into martini glasses without it shooting up the other side.
• You can either do what I do, or turn the regulator off and release some pressure using the ring pull valve till the needle drops to 20psi, then turn up the regulator till the needle moves upward a little indicating the regulator will now hold the pressure steady at 20psi.
• When you pour your martini into a glass what was a black liquid should now pour as a creamy paler colour. This will settle in the glass to form a dense foam on top and black base over about 10-25 seconds. The lighter the colour the more nitrogen has dissolved and the better the effect will be and the longer to settle.
• You can keep pouring drinks now until you see the pressure start to drop, ie the needle moves down, indicating the bulb is empty. Turn the regulator off, insert a new bulb and turn the pressure back up to 20psi to continue pouring.
• If you won't be pouring anymore drinks for a while turn the pressure back up to 50psi while storing to keep the gas dissolved in the mix.
• When you next go to pour a drink (whether it's a few hours, a day or a week later) give the keg a quick shake before dropping the pressure again to pour.

Trouble Shooting

• We have tested hundreds of brands of coffee, pre-made by other companies and by ourselves with various beans. Some just don't work well and the foam dissapates quickly, this could be due to oil content, strength of brew or other factors. Boston Black is designed specifically for making espresso martinis by a crew in Melbourne and it's used in over 50 bars around Australia, they brew in large batches that are always exactly the same. Chillbru have been using our kegs for years to demonstrate and run events with their coffee, it's made fresh weekly in small batches, it's delicious but has a shorter expiry period. We are certain that if you follow the directions these will work correctly, we can't guarantee anything else you try will work as well. Espresso or very strong cold brew concentrate generally will work fine though if you follow these instructions.
• The ice is important for 3 reasons, it dilutes the mix to where it's supposed to be, it brings the temperature down to at or below 0 deg and it "smashes" the gas into the liquid when you give it a shake. Don't leave it out.
• Higher alcohol content can impact the ability of the cocktail to hold foam sometimes, if the foam dissapates too quickly after following the instructions above try adding more coffee to the keg and infusing with nitrogen again. Considering how easy it is to get your next cocktail it's not a bad idea to reduce the alcohol content a bit anyway ;-) 

Espresso Martini Keg Recipe

Our recipe calls for Chill Bru or Boston Black Cold Brew Concentrate, Vodka, Kahlua and Ice in a 1:1:1:0.4 ratio.

In a 2L keg that is 500ml of each liquid with one of our trays of ice (200ml).

• You can increase or decrease the volume you make in a batch just maintain ratios the same or similar.
• As above you can increase the ratio of coffee if you choose to. This will reduce the alcohol content per cocktail and potentially hold foam longer if it's disappearing too quickly.
• The number of Nitrogen bulbs you use depends on how much empty space you have to fill with gas in the keg, how much gas you absorb into the liquid and whether you release gas to drop the pressure or just pour a drink to do so.

Generally a 2L keg filled following the guide above will use 2-3 bulbs to dispense.

Nitrous oxide has much more gas per bulb (8g) than pure nitrogen (2g) and also absorbs more easily into liquid, but in our experiments the foam is more affected by alcohol content.

• You use a lot less bulbs if you use nitrous oxide instead of pure nitrogen in nitro coffee / lower alcohol content cocktails or if you use a combination of pure nitrogen and nitrous oxide but it's a matter of experimenting to get the outcome you want.

For events, businesses and parties where you will be going through larger quantities of nitro infused liquid we also have disposable gas bottles that hold the equivalent of 140 of the bulbs and just need an adapter to attach to the iKegger 2.0 mini regulator.