Carbonation: The Final Ingredient
Carbonation may be one of the most overlooked and underrated component of beer. Water, barley, hops, and yeast take center stage, and it is often said that these are only four items needed to make beer. It is easy to believe that these four ingredients alone determine the outcome of the final product, but carbonation plays an extremely important role in the drinker’s experience. Carbonation affects all aspects of a beer including flavor, aroma, appearance, and mouth feel. Some may argue that carbonation is not a true “ingredient” in the same sense as the “big four”. In the case of naturally carbonated beers, this can be understood given that the carbonation is a by-product of the yeast’s “secondary fermentation” in the bottle, much like alcohol itself is a by-product of yeast activity rather than an actual ingredient added by the brewer. However, this is less true in the case of beers force-carbonated from an external CO2 source (Look here for more information specifically on keg carbonation). Regardless of how it is introduced, the level of carbonation in a beer has a tremendous effect on the final product, and is a component worthy of scrutiny for homebrewers interested in maximum control over their finished product.
How Much Carbonation is Needed?
Traditionally, certain styles of beer have been served with a particular level of CO2, and the amount of CO2 dissolved into a beer can vary widely depending on the style. While there are no laws against carbonating your beer to any level you want, it can be helpful for the homebrewer to understand the traditional guidelines. When entering a beer into a contest, or testing your brewing skills by cloning a favorite commercial beer, getting the carbonation level correct is important to the overall sensory experience.
How is Carbonation Calculated and Measured?
Carbonation levels are typically measured in either grams per liter (g/l), or in “volumes” of CO2. Most charts and recipes used by homebrewers use volumes of CO2. 1 volume of CO2 is defined as 1 liter of CO2 at 1 atmosphere of pressure dissolved in 1 liter of liquid (beer in this case). An approximate conversion is 2 g/l to 1 volume of CO2, so if a recipe specifies 5.0 g/l of CO2, this would equate to 2.5 volumes of CO2. It is somewhat of an abstract concept, so to understand what a certain volume of CO2 “feels like” in a beer, it is helpful to look at a few common commercial examples in order to calibrate the brewer’s reference point. The following table lists a few common commercial beers that most homebrewers would be familiar with and their corresponding carbonation levels. These beers display a wide range of carbonation, and provide the brewer with a good reference point for what different carbonation levels contribute to a beer, from barely-carbonated English Ales, to highly-carbonated German Weissbiers. The majority of commercial beers will fall somewhere in the middle, in the 2.4-2.6 range.
Carbonation Levels When Entering A Competition
BJCP (Beer Judge Certification Program) guidelines provide the specific parameters for each beer style, including acceptable range of CO2 Volumes. However, there are hundreds of individual beer styles within the BJCP guidelines, which can be overwhelming. Furthermore, carbonation ranges tend to overlap greatly and are often consistent to a degree amongst general regional styles. Therefore, a simplified carbonation-by-style reference can be very helpful to the homebrewer. Starting with the 2015 BJCP style guidelines, beers were put into logical groupings based on general regional characteristics, and then by common BJCP carbonation ranges. For example, it is common for many ales of the British isles (ESB, mild, stout, etc.) to be carbonated to a very low level, which contributes significantly to the sensory profile for these beers - e.g. a highly carbonated mild would be a completely different beer. So, it makes sense to group these beers into a style grouping, even though BJCP specifies nearly a dozen distinct styles within this grouping. There are many ways to slice and dice this, but for the purposes of this article, five general styles were chosen: Belgian, German/European, English/Irish/Scottish, American, and “Other”. (It was surprisingly easy to group carbonation types by geographic region, notwithstanding the “Other” category.) Within each general style, 3-5 sub-styles were selected to show the diversity (and sometimes lack thereof) within the regional styles in terms of carbonation level. The table below gives two data points for each style: the BJCP carbonation range, and a recommended carbonation target within that range based on traditional examples. A final disclaimer: as mentioned above, the BJCP guidelines and the recommendations within the chart are just that: guidelines and recommendations. Surely, there are commercial examples of these styles that do not fall within these guidelines, but in general, these recommendations reflect what is typical of the styles. Particularly in the “Other” category, there will be wide variation in commercial examples, and much comes down to personal preference. If you prefer a simpler approach to carbonation, check out Homebrew Supply's carbonation drops, which makes bottle conditioning your beer a snap!