from “The Complete Joy of Home Brewing“, ed. 3 by Charlie Papazian
KRAEUSENING YOUR BEER
NATURAL CARBONATION WITHOUT CORN SUGAR
Kraeusening (besides being difficult to spell) is the process of priming beer with a measured amount of gyle. Gyle is the amount of unfermented wort a brewer uses to prime the finished beer for carbonation purposes. Gyle can be used instead of the simpler homebrewing procedure of adding 3/4 cup (175 ml) of corn sugar for every 5 gallons (19 l) of finished beer. It allows the homebrewer to make a brew from 100 percent barley malt, hops, water and yeast.
Kraeusening, a process using natural ingredients, is used by many com¬mercial brewers to naturally condition beer. On any given day, breweries are always brewing and packaging one batch of beer or another. It is convenient for commercial breweries to add a small amount of the new beer to the finished beer. But for the homebrewer, brewing and bottling in the same day is often more time-involving than desirable (it doesn’t leave you with as much time to relax and enjoy…).
A PRACTICAL METHOD FOR THE HOMEBREWER
Aha! You don’t have to brew the same day as you are bottling in order to kraeusen your beer. There is an easier, more convenient way. A homebrewer only has to save a measured amount of unfermented sterile wort stored in a sealed container in the refrigerator. The gyle must be taken from the wort before yeast has been added. When it is time to bottle, the stored gyle is added to the finished beer.
The big question is: How much wort should be saved as gyle? The sugar content and specific gravity of worts will vary with every batch. Keeping that in mind, I have reduced an involved mathematical equation to a simple formula that anyone can use. This formula will allow you to calculate accurately the amount of gyle to save in order to prime any amount of beer being brewed.
There is one assumption that I make: that priming is based on a priming rate of about 3/4 cup (175 ml) of corn sugar per 5 gallons (19L). The formula is:
Quarts of gyle = (12 X gallons of wort)/[(specific gravity - 1) X 1000]
For example, for 5 gallons (19L) of wort that has a specific gravity of 1.040:
Quarts of gyle = (12x5)/[(1.040—l)x 1000] = 60/40
NOTE: The denominator is simply equal to the last 2 digits of the specific gravity.
Quarts of gyle = 1 1/2
If the Balling scale is used instead of specific gravity, then the formula becomes:
Quarts of gyle = (3 X gallons of wort)/(degrees Bailing)
NOTE: The gyle must be removed from your batch of wort before yeast is pitched. It is important that it be sealed in a sterile jar and kept cold in the refrigerator.