When brewers are looking to take their tasty, exciting – but still – beverage and hook it up with some bubbly life, they really have two basic options. The first and more traditional route is to ‘naturally carbonate’, where in they add some form of sugar source – sterilized or actively fermenting wort, sugar, honey, DME, etc. – bottle or keg it, and let the yeast ferment out the small sugar source, releasing CO2 and making the magic happen under pressure.
The second method is ‘forced carbonation’ – the method I tend to use most regularly at home. While I certainly do not frown upon natural carbonation (if for no other reason than I don’t want CAMRA to show up at my door with torches and pitchforks…I love those guys), I prefer forced carbing for most of my brewing purposes.
Uh… How Do I Do It?
Forced carbonation is rather simple. You rack your still beer into a keg or other sealed and sanitized container that has a gas in valve of some kind….there are modified pop bottle caps that you can purchase to carbonate two litres of beer at a time, for example. Then, for maximum carbonating efficiency, you ensure the beer is cold, as CO2 is much more soluble in a cold solution – this means less pressure will be required to hit the same level of carbonation. Lastly, connect the beer vessel to a CO2 cylinder and pressurize, leaving the gas connected and hitting the solution with pressure. The solution will absorb the CO2, leaving you with a carbonated beverage.
That might sound quite simple – and it is – but you do have to take care to ensure that your beer is properly carbonated. You need to know your rough beer temperature and your target carbonation (volumes of CO2 in solution). From there, it is easy to find a chart online that tells you how much pressure to use at a certain temperature to hit a certain carbonation level. Sort that out, leave the gas on and the beer cold, and it’ll all happen…usually in less than a week.
There are some brewers out there who use a variety of changes to this method, such as hitting the beer with very high temps for maybe a day or two, hoping they hit the level they were seeking before it fully carbonates to the level of pressure being used. Another option is to hit the beer with gas and shake the keg, roll it on the floor, ride it like a bull – whatever you like. This puts more of the beer in direct contact with the gas right away, and it can leave to almost instant carbonation. I haven’t done this shake n’ bake method myself, but I have heard reports that the carbonation level is difficult to nail, and the carbonation will not necessarily be as stable as it might be if you used a little more precision and patience. However, that being said, sometimes you just need that beer right freaking meow, I suppose!
Upsides of Forced Carbonation
You can hit a desired level of carbonation by quickly referencing a kegging chart, using your beer temperature and desired level of carbonation (I know you can do basically the same with natural carbonation, by calculating the required sugar based on OG and desired carbonation…I just find this less daunting).
You do not require any new ingredients (wort, yeast, sugar, whatever) to carbonate the beer. If you have an existing keg setup, you are able to make this happen.
It is ‘cleaner’ in the bottle than naturally carbonated beer – assuming that you might want to bottle a bit after you keg and carbonate…competiton, anyone? As you are not adding or multiplying your yeast content to take on the new sugar source, there won’t be that same layer of yeast in the bottle, so carefully decanting homebrew to avoid cloudy beer is a thing of the past.
Don’t have a kegging system but think this sounds cool? Put together a kegging system. You’ll love it. There, another upside to forced carbonation!
Do what works for you. Do a combination of them. I know there are some styles that are sweet to naturally carbonate – and some that are just easier, as they have extremely high expected carbonation levels, and serving or bottling from a keg can be a hassel (or sometimes impossible!) at those levels. I have a buddy who force carbonates most of his beers, but he also naturally carbonates some of them in the keg, and then still serves them from that keg using a CO2 cylinder. Find an awesome approach and run with it.