February 19, 2020

Carbonating Beer Using Specialty Techniques

There are some very unique processes that go well beyond the advanced conditioning material. These include more historical methods rather than the exacting science we have covered thus far. We’ll cover casks and firkins, kräusening, and using wild yeast and bacteria.

Carbonation of Cask and Firkins

Cask conditioned ales are the original English ales. The beer is added directly to a cask with priming sugar, yeast and a small number of hops. They are served at cellar temperatures (~55F) from either gravity or pulled using a beer engine. The low volume of carbonation, the added hops, and the warmer temperatures make these ales truly magnificent. Although not difficult to do, real ale does require some additional hardware.

All we need to do is treat the polypin as we would any other container. After you are sure your beer is completely fermented and has been cleared you can rack directly into your polypin. We really want quite a low level of carbonation so I like to shoot for about 1.8 volumes or so. Yeast at the above rates. One small change is the addition of a small quantity of hops to this pin. Just add .25 to .5 ounce of hops to a hop bag and insert that into your pin. Get it all mixed in your pin and allow a week or so for carbonation. After carbonation, it is of the utmost importance to introduce oxygen into this beer at this time. ***PLEASE NOTE - I KNOW THIS GOES AGAINST EVERYTHING YOU’VE BEEN TAUGHT BUT STAY WITH ME! This limited oxygen exposure is mandatory to get the true cask flavors. A cask is basically open to the environment and every pull of the engine draws more air into it. Because we are using a poly-pin, as we draw pins off, they collapse ensuring there is no oxygen exposure. This is the benefit of using them but a hindrance in this instance. We need to get around this. Here is how you do it:

  1. Open the spigot and bleed off the extra pressure
  2. Compress the poly-pin to push out as much of the CO2 as possible
  3. Let the weight of the beer pull open the poly-pin and draw in as much air as possible
  4. Close the spigot when it’s full. It should feel bloated.
  5. Give the whole poly-pin a good shake to get the oxygen into the beer.
  6. Wait about a week and serve either by gravity or by beer engine.

It's best to store these beers on a downward angle towards the spigot as the yeast will settle out of solution and won’t end up in your glass. If you are having real trouble getting yeast to fall out of the solution you can use Isinglass at a rate of 1oz/ 5-6 gal (each poly-pin).

Kräusening (Mit Speise)

In Germany, the Reinheitsgebot allows only the use of malt, hops, yeast, and water in brewing. This leaves the problem of carbonating the beer without the benefit of any regular sugars. What nearly all German brewers do is add a portion of fermenting beer to the finished beer. The process is called ‘kräusening’ in that you are taking part in an actively fermenting batch at high kräusen and adding it to a finished batch. This not only provides the sugar for carbonation but also the yeast. This technique can be used for bottles or kegging. The latter is practiced in German where the carbonated beer is then filtered before bottling.

For the home brewer there are basically two ways to accomplish this:

1. Traditional Kräusening - Add Actively Fermenting Wort 
Commercial brewers brew the same recipes over and over. Inasmuch, they always have an actively fermenting beer that is the same as the beer type as the one they want to carbonate. This isn’t usually the case for home brewers. Let's just say for the sake of argument you are brewing the same beer you need to carbonate although any beer will work. If not, the closer the new beer to the one you will be carbonating the better. Each beer will be slightly different in that its fermentability will vary from one recipe to the next. Keep in mind the higher the final gravity of the beer will change the amount of kräusen that you add. The higher the FG the less kräusen you will need.

The amount of kräusen to add is dependent on the amount of carbonation needed and the gravity of the kräusen. Use this example as a reference:

Let’s say we have 5 gallons of Oktoberfest sitting at 32F that we need carbonated. From the priming calculator, we see that we need 2.5 volumes of CO2. Our new batch of Oktoberfest is fermenting at high kräusen and has an SG of 1.038. This means we will need approximately .75qts (700ml) of kräusen to carbonate our beer.

2. Modified Kräusening - Make a Starter from Saved Wort 
As homebrewers we don’t brew all that regularly and usually like to do many different recipes. Brewing the same beer twice in a row isn’t appealing to most people. This puts a damper on a traditional kräusen to prime your beer. We, however, can do what I call a ‘modified’ kräusen. The procedure is basically the same as for the traditional method except that you save some of your wort after the boil. We can approximate how much kräusen we will need using the above methods. I then suggest you double it until you are comfortable with the process.

We will use our Oktoberfest again as an example. After the boil we will save 2 quarts of wort in a sanitized container. Since this is a lager most people either choose to freeze this wort or to simply ‘can’ it in mason jars. When you are ready to prime your beer all you need to do is basically make a starter with this beer. Add the approximate amount of yeast as indicated in the ‘yeast rate’ section. At high kräusen, test the gravity and then do your final calculations on the amount to add (this is why we save extra).

Let’s say we have the same 5 gallons of Schwarzbier sitting at 65F that we need carbonated. From the priming calculator, we see that we need 2.3 volumes of CO2. We canned 2qts of the original boiled wort and has an OG of 1.055. We add 100,000cells yeast/ml and let it start to ferment. At high kräusen this ‘starter’ is at 1.029. When we plug this into our calculator we see that we need 1.5qts (~1400ml) of the 2qt starter.

Kräusen Examples - 5 GALLONS
Type  Yeast  Temp  Kräusen S.G. Kräusen vol







2.5ml Wyeast



1.5qt (~1400ml)

Carbonating Beer With Wild Yeast And Bacteria
There is also interest in the use of non-saccharomyces yeast and various ‘bugs’ in beer production. Traditionally most were contaminants that gave a specific character to the beers. The ‘aged’ flavor in English stock ales and stouts was found to come from Brettanomyces claussenii (aka B. anomalous). B. lambicus and B. bruxellensis provide the main ‘funky’ component to lambics. The bacteria pediococcus cerevisiae and Lactobacillus delbrueckii respectively provided the acid to lambics and Berliner weiss. A very simple way to start using these bugs is to use them in your bottling process.

Characteristics Of Wild Yeast And Bacteria
Style Type Of Bug Character BU Effect

B. Bruxellensis


Barn Yard


B. Clausenii


Pineapple, aged Tobacco


B. Lambicus


Cherry Pie


L. Delbrueckii


Lactic Acid


P. Cerevisiae


Lactic acid



Wild Yeast and Bacteria Pitching Chart

Style Pitch Rate per ml  Wyeast per Package


3,000 to 1million

75 billion Bacteria


1:4-5 Vol of Yeast Used

10 billion

You can substitute regular priming yeast with any of the brett stains and still do the same function. The only thing you need to remember is that brett can ferment some of the dextrins that saccharomyces can not so plan ahead for that depending on the body of your finished beer and the amount of priming sugar you will add. Brettanomyces can also eat the sugars (cellobiose) from the oak. Although the beer will carbonate quite quickly, it will take a while for any brett character to develop. It should also be noted that your choice of yeast you use to ferment the beer plays a role in the amount of brett character that will ultimately develop. Using a plain American ale yeast will give you a lot less character than one that is full of phenolics and higher alcohols like the Belgian strains. FWIW - Brett usually won’t go below 1.006 FG but some strains have been known to go down to 1.002. 

Unlike yeast, these bacteria will not actually ferment sugar to produce carbonation. You will be using them, along with a bottling yeast strain, to give a unique character to your beer. The biggest hindrance to using these bacteria is the presence of hops. When deciding which beers to put these in it is imperative that the BUs are below 10. The farther you get over 10, the more likely these bacteria aren’t going to work for you. Traditionally they are pitched at a ratio of 5 parts yeast to 1 part bacteria. It is also not a good idea to make a starter of these cultures but to add them directly from their packaging. Lactobacillus can do its job aerobic and anaerobically but prefers the latter. Pediococcus is much more an anaerobe but can produce a good amount of diacetyl.

Examples - 5 GALLONS (same pitching rates as above)
Style Vol CO2 Wanted  Temp Amount Sugar  Vol yeast Vol of bug*

Berliner Weiss



1.5 cups DME

2.5ml Wyeast

4.75ml L. delbreukii (1:4)

Brown Porter



3.0oz brown sugar

No yeast

12.5ml B. lambicus & 12.5ml B. bruxellensis

Belgian Tripel



6.25oz table sugar

No yeast

25ml B. clausenii




125g Corn Sugar

25ml Wyeast

~1ml B. bruxellensis

*1mill cells/ ml yeast and 3,000 cells/ml brett WYEAST Bacteria - ~10 billion cells & 100ml = 100 million cells/ ml. Brett - ~75 billion cells & 100 ml = 750 million cells/ ml

Read More About Carbonating Beer:

How Do I Carbonate Beer - Carbonating your beer in bottles and kegs
The Complete Guide to Kegging Vs. Bottling - What's right for you
Why Didn't My Beer Carbonate? - A few key issues why your beer didn't carbonate
Over Carbonated Beer - Dial in your carbonation
How to Pour Beer from the Tap Without the Foam - Pour a perfect pint


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