Putting cocktails on tap has been long debated in the craft cocktail world. Like pineapple on pizza and leggings as pants, people have mixed feelings about whether or not this modern trend is appropriate. Some people are firm believers that a cocktail should be a hands on experience for the bartender, resulting in a better guest experience because it feels personal. I, however, take part in the belief that kegged cocktails can improve your bar program by letting you do the heavy lifting of crafting the drink before service. This allows you to spend more time with your guests while delivering them a perfectly balanced cocktail with every pull of the tap handle.
With that said, kegging a cocktail is by no means foolproof, so there are some things to consider before pouring your recipes into a keg:
Find a Keg (and learn how to use it)
Finding a keg is step one. The typical keg sizes you will find are 2.5, 3, 5, 10, and 15 gallon barrels. You can find new or used kegs through beer making resources such as www.homebrewing.org, or even on Amazon for a reasonable price. A 5 gallon keg or smaller is ideal for cocktails.
Kegs come in “ball lock” or “pin lock” varieties. Neither one is necessarily better than the other, but they do have a few differences. Ball lock kegs are taller and skinnier, and usually a bit pricier. Ball lock kegs also have a manual pressure release valve, in addition to the automatic pressure release valve, which both styles have. The automatic release valve is a safety precaution that will automatically vent if the pressure gets too high. The manual release valve gives you more control over the pressure in the keg. If you need a shorter/wider keg for your space, or if you would simply like to save some money, go with a pin lock keg.
Both kegs work the same way, the ball/pin differentiation is simply to indicate how the lines are connected to the posts on the keg. The posts on the keg can be nearly indistinguishable but it is very important that you attach them to the correct lines. One post is for gas (in) the other is for liquid (out). The gas post is always marked by some type of groove on the post (the exact marking will vary by brand), while the liquid post will be smooth. An easy way to remember is
Gas = Grooved, Beer (or in this case cocktails!) = Blank
The liquid/out post is attached to a dip tube that goes all the way to the bottom of the keg. As gas flows in from the top of the keg, it helps build pressure within the keg to dispense liquid from the bottom of the dip tube all the way out the top and through the liquid line.
** NOTE ** In order to connect your lines to the posts on the keg, you may need to install a ball lock conversion kit to your existing kegerator lines. This is a simple procedure that allows you to connect the liquid and gas lines to your kegerators existing lines without sacrificing the ability to connect to standard ball bearing style kegs.
Pick a cocktail (the fun part!)
Theoretically, you can keg just about any cocktail. But when you are starting out it is best to stick with simple cocktails until you are comfortable with how kegging will affect different recipes.
If you want to serve your cocktail directly from the tap (e.g. without shaking or stirring) you will have to include the dilution that would be introduced to the drink from shaking or stirring. You can test how much dilution you want in your batch by measuring out the weight of the cocktail before shaking or stirring, and then weighing it again afterward. The difference in weight will be your water content.
Ex: Cocktail before shaking weighs 3 oz → after shaking with ice weighs 4 oz → 1 oz of water should be added to the initial cocktail recipe before multiplying it to create a batch.
Once you have your recipe for an individual cocktail and its dilution established, you will want to multiply it to match the size of the keg.
Helpful Notes for Multiplying:
1 L = 33.8 oz
1 Gallon = 3.78 L = 128 oz
5 Gallon (average keg) = 19 L = 640 oz
Ingredient Viscosity & Shelf Stability
The ingredients in cocktails each have different weights. This is fine when you are shaking or stirring them one at a time, but when it is sitting in a keg for a longer period of time the heavier ingredients may settle to the bottom, resulting in an unbalanced drink. Because of this, it is best to stay away from heavy fruit juices or overly thick syrups. Keep your simple syrups at a 1:1 ratio. If you want to use honey, maple, or agave as a sweetener, mix it with an equal part of hot water to create a less viscous syrup.
I would highly recommend clarifying any juices you use in a kegged cocktail. To learn how, follow this very helpful link from A Bar Above.
If you don’t choose to clarify your juices, you will have to regularly shake your keg to make sure it is well blended. Be wary that shaking the keg will affect the carbonation, making it more bubbly with each shake.
Consider the shelf stability of everything you put in the keg, especially if you are just getting started and don’t yet know how quickly you will sell through this product. Not only do you want to avoid dumping out a costly cocktail batch, but you really don’t want expired ingredients breeding bacteria in your kegs or lines. If you must use juice, always opt for cold pressed, and consider using extracts or concentrates in lieu of fresh ingredients if you are making fruit or herb flavored syrups for kegs.
Understand Solubility & Pressurizing Your Keg
Once you have your recipe batched and poured into the keg, it’s time to ~charge~ the keg.
In order to tap your cocktail, you need CO2 in it to push it through the line. You can use a little for a flat cocktail, or a lot for a fizzy cocktail, but you will need some type of gaseous pressure inside of the tank. In order to do this there are a couple of methods you can used. For both of them you must begin by removing the gas socket from the gas line and replacing it with the liquid socket from the liquid line. The sockets are only designed to fit their respective posts, so you have to do this in order to force CO2 into the liquid line. The reason for doing this is to force the gas down the dip tube that is attached to the liquid line, so that the gas goes to the bottom of the keg and rises up throughout the whole cocktail. Once you’ve done this, slowly turn up the pressure to 5 PSI and proceed to one of the following methods of carbonation:
"In the first method you will use a lower level of CO2 pressure and carbonate for a longer period of time.
With the gas line free of leaks, use the keg’s pressure release valve to briefly bleed off some gas to ensure that gas is flowing through the entire keg as it should. In addition to hearing the release of gas as it exits the keg you should also listen for bubbling, which will indicate that CO2 is properly running from the gas cylinder, through the regulator and gas line, down through the dip tube, and up through the beer.
Once you have confirmed that the entire system is working properly, adjust the regulator to raise the pressure to 20 PSI. Allow the keg to carbonate for 7-10 days, and then check the carbonation levels.
Remember to switch and reattach the gas and liquid sockets to their proper lines and to lower the gas supply to serving pressure before doing testing.
The other force-carbing method is similar but will carbonate at a faster rate. However, it’s important to note that it involves more effort.
First, attach the gas supply to the keg in the same manner as the first method. Once the system is hooked up, turn the gas supply up to 30 PSI.
Then, gently shake the keg to stir up the beer inside. You should immediately hear bubbling within the keg. Agitating the keg increases the contact area between CO2 and beer even further, promoting faster diffusion of CO2 into the beer.
Continue to shake the keg for 20-30 minutes then lower the pressure to 20 PSI and allow the keg to carbonate for 2-3 days. Check the carbonation levels and enjoy!"
Jeff Flowers for Kegerator.com 2014
When you are making a simple syrup, you typically heat it up in order to get the sugar to dissolve into the water. The reason this works is because solids are more water soluble at high temperatures. The opposite is true of gasses - these are soluble at lower temperatures. Because of this, your keg needs to be cold during the charging process. You can charge the keg even more effectively by using ice as the water content in your cocktail. Simply freeze the appropriate amount of water for the batch, then add it to the keg before charging.
It is important to note that CO2 gas can still give you fairly flat cocktails as long as you don’t charge the keg long, and keep your serving pressure low (around 5 psi), although the exact carbonation of the drink may fluctuate overtime.
Nitrogen can also be used as the gas element in your cocktail, or a combination of both Nitrogen and CO2.
Keep Your Lines Clean
Before putting your cocktail on the line, make sure the line is clean. If there are remnants of past product in the line, it will get into your cocktail and negate all of the hard work put into the drink. Worse than that, lines can be full of bacteria, and while most won’t make you sick they can add a sour, spoiled taste to your product. While you’re at it, make sure your keg is deep cleaned if it has been used previously - lactobacillus and other bacteria can live inside there too.
If you are concerned your line may affect your cocktail, simply fill the keg with water and run it through the tap line to taste test.
Have Fun With It
Perfecting kegged cocktails can be intimidating, but have fun with it! It is a process that requires patience, passion, and a basic understanding of physics - which means it is an incredible way to hone your skills as a bartender and manager. Challenge your best bartenders and yourself to improve the balance and carbonation styles of your kegged cocktails over time, and use them as a tool to elevate your entire beverage program.
If you’re thirsty for more information on this topic, check out the links below: