My letter was published in the March/April 2016 issue. It reviews the causes of under carbonation in bottle conditioned beer and explains how to diagnose and fix a problem when it occurs.
October 29, 2015
Letter to the editor of Zymurgy Magazine
Thank you for your response to Bill Bartman’s letter about under carbonation in his RIS (November/December 2015.) It provided a thorough explanation of insuring yeast health at priming time. But shouldn’t a diagnosis also include the basics? Improper bottle conditioning plagues us all- homebrewers and commercial brewers alike. To do it consistently is not easy. Success depends on:
– Accurate measurement of volume. Not as easy as it would seem.
– Accurate measurement of finished gravity, for the record.
– Accurate input for temperature of green beer. In most calculators, the temperature defines assumed residual CO2. This temperature should be based on the highest temperature reached during fermentation, not the temperature of the green beer at bottling time. However, if you added fruit, cold crashed, had extended aging, or aged in a barrel, it is much harder to assign an accurate temperature. That takes trial and error, and knowing your beer well.
– Correct amount of priming sugar, measured by weight, based on measurements above. Make sure the sugar solution stays in suspension during bottling.
– Following all of your instructions about using the right selection, amount, and preparation of healthy yeast.
– Storing the freshly primed bottled beer at the correct temperature*. This is crucial. High gravity Belgian and American style strong ales should be stored for 4-8 weeks at 68-74 degrees f. to ensure thorough carbonation. Possibly, bottles need to be rotated to ensure even heat. Overly low temps for conditioning are one of the main causes of under carbonated beer among brewer’s I know.
Finally, Bill could also partially diagnose the cause of under carbonation in his bottled beer by uncapping and taking a gravity reading. If the gravity is above what it was at bottling time, then the sugar was not consumed by yeast and he needs to re-yeast as per your instructions. If the gravity is the same, then re-fermentation did not occur because there was not enough sugar added.
What do you think? Thank you for your column!
Berks County, PA
* Yeast: The Practical Guide to Beer Fermentation by Chris White and Jamil Zainasheff
* Brew Like a Monk by Stan Hieronymous.
* On the Yeast Guide to Bottle Conditioning by Thomas Miller. BYO 11/2000
* American Sour Beers by Michael Tonsmeire