Bottle conditioning is certainly not the sexiest of beer topics. In all the classes I’ve taught, I don’t think I’ve had one person ask about it. But it’s always a topic I talk about. And usually, it’s a topic that sparks the interest of at least a few people. For me, Bottle conditioning is an incredibly important subject when it comes to the nature of the beers I’m most passionate about: Belgian beer.
Q & Ale: What is Bottle Conditioning?
In its simplest explanation, bottle conditioning (also known as bottle refermentation) is a natural method of creating carbonation in the bottle, can, or keg. Home brewers are very familiar with the process. You mix in some priming sugar, usually sucrose or dextrose, to the finished beer then package it. The yeast that’s still in the liquid eats the added sugar and creates the normal byproducts of CO2 and Alcohol. But since the CO2 has nowhere to escape to, it dissolves into the liquid creating beer’s characteristic sparkle. Simple enough.
Well, at least on the home brewing level. In commercial brewing, it’s a bit more complex. Yeast, brewing at a commercial level, is pretty exhausted by the time it’s finished the batch and not in an ideal condition for additional work in the harsh conditions of a package: increased pH and alcohol. Instead, commercial brewers will select a different strain to do the work. This new strain is mixed with priming sugar and then added to the bottle so it can go to work. The brewer will calculate the amount of pressure they want in the final product, calculate the remaining fermentables in the beer then mix in the proper amount of sugar and yeast to get to anywhere from 2.5 volumes to 4+ volumes (in the case of Belgian specialty beers).
Once the sugar and yeast are added, the bottles will spend several weeks in a warm room, usually 70-77 degrees F so the yeast will have the best conditions for finishing the beer.
Partial Bottle Conditioning
While full bottle conditioning is the ideal, it’s time consuming and if done with less than precise technique can result in varying degrees of carbonation that can lead to anything from flat beer to a gushing bottle to exploding bottles. To combat this, many breweries will partially bottle condition their beers. This means they’ll use the more modern method of forced carbonation to form the majority of the volume load, usually between 2.2 and 2.5 volumes, then add in a small dosage to round out the process. This refines the carbonation giving a better sparkle than forced carbonation but won’t be quite as elegant or complex as a true, full bottle conditioning.
Bottle conditioning provides more benefits than just bubbles. Although those bubbles will be of a finer quality: smaller with a more intense but elegant character; the process leads to a beer with deeper complexity, better head retention, better shelf life, better aging prospects, and a finer texture. This is the real reason I care about bottle conditioning so much. It leads to a far superior beer.
This is one of the main reasons Belgian beers taste so great from the bottle. You get to try the product as intended in its best form, not filtered and pasteurized for draft stability. The flavors and texture of a bottle conditioned beer are truly unbeatable.