"What Is Bottle Conditioning?" by Mike Sherlock

Have you ever had a beer that had the phrase "bottle conditioned" on the label? Probably not. Although some of the smaller craft breweries and most home brewers use this technique. Generally, commercial brewers use a technique called "force carbonation." But what do these terms mean?

When yeast is introduced to unfermented beer (called "wort"), the single-cell organisms digest the sugars contained therein and excrete ethanol and carbon dioxide (CO2). In wine making, the carbon dioxide is extracted (usually by stirring it really fast). Those using Méthode Champenoise (French for "Champagne Method") trap the gas within the wine. This is the same phenomena that makes bread rise (trapping the gas in dough rather than a liquid).

During the fermentation process, brewers, both at home and in commercial breweries, allow the carbon dioxide to escape. If we didn't, then the wort would be under pressure and would hinder the efforts of the yeast. So after fermentation, one has to figure out a way to get the bubbles back into the finished beer. After all, beer just isn't beer unless it has bubbles.

Forced carbonation is simply the act of dissolving CO2 gas in finished beer. It's the exact same way Coca-Cola gets bubbles in their beverages. One just has to figure out how many "volumes" of CO2 one wants in the beer. A "volume" is 1 liter of CO2 at 1 atmosphere in 1 liter of liquid. I know that sounds very scientific, and I might have just caused your eyes to glaze over, but it's rather simple. Basically, each beer style has a standard volumes of CO2; fizzy American Lagers (Miller, Budweiser) will have 2.5 - 2.7 volumes of CO2 where flatter Irish Stouts (Guinness, Beamish) have 1.6 - 2.0. Then there is a standard table one may check to translate volumes to pounds-per-square-inch (PSI) of CO2 by the temperature the beer will be kept at. CO2 dissolves more effectively in cooler liquids (that’s why warm soda explodes easily).

So if the paragraph above gave you a headache, then bottle conditioning may be for you. It's actually the same technique used to get bubbles in Champagne. When the beer is ready to be bottled, the yeast within have pretty much consumed all the fermentable sugars. The yeast is still in there, just kind of hanging out (dead yeast have been removed by this point in a process called "fining"). So the brewer adds a little more sugar (usually corn sugar) and immediately bottles the beer. In the bottle, the yeast eats this newfound sugar and makes more ethanol and carbon dioxide. But this time, the cap is on, so the gas has nowhere to go. Bottle conditioning results in a slightly higher alcohol-by-volume (ABV) than a comparable force-carbonated beer.

So which way is best? That’s a matter of opinion. I force-carbonate when I keg (yes, home brewers can keg beer) since I’m going to have to hook it up to the CO2 tank anyway and I like having control over how many bubbles are in my beer. A home brewer can’t effectively force-carbonate bottled beer without some fancy equipment. Just about every bottled home brew is bottle-conditioned. Occasionally, one will see a special commercial beer that has been bottle-conditioned, but that’s the exception.

Bottle conditioning does not scale well. It can create some inconsistencies, like one bottle in a case being slightly more or less bubbly than the next. Besides, American commercial brewers filter and pasteurize their beer to make it look crystal clear and give it a longer shelf life. This process kills any residual yeast making bottle conditioning unfeasible for them.

So all thirsty Nobles are encouraged to stop by and meet the Brewmeisters at the Lu Lu Shriners Family Picnic on July 10th. While you’re at it, enjoy a bottle-conditioned, light, Summer ale made by us! We’re looking to grow our ranks and no brewing experience is required.