exBEERiment | Force Carbonation: Set-And-Forget vs. Burst Carbonation In A Kölsch

Author: Jake Huolihan

While beer is often said to consist of water, malt, hops, and yeast, many would contend a fifth element is equally as essential– carbonation. From barely bubbly British ale to sparkling Belgian Saison, carbonation contributes a number of desirable characteristics to beer that increase its overall enjoyability.

The two primary carbonation methods are natural, where carbon dioxide (CO2) is produced by yeast consuming sugar, and force, which has several sub-approaches that all involve “forcing” CO2 into solution through pressure. For the more patient brewers, there’s the set-and-forget method where the beer is left at serving pressure, usually 12-15 psi, for a week or longer before it reaches the desired level of carbonation. This works great, it just takes a while, which is why some rely on the burst carbonation method, which involves leaving the beer under a much higher pressure for a fraction of the time.

I initially relied on the set-and-forget method when I started kegging, but made the switch to burst carbonation many years ago and haven’t looked back. However, some claim that such rapid forcing CO2 into beer can result in undesirable characteristics, namely carbonic bite. With one past xBmt showing tasters could not reliably distinguish Blonde Ales carbonated using both methods, I decided to test it out again on a Kölsch-style beer.

| PURPOSE |

To evaluate the differences between a Kölsch carbonated using the set-and-forget method and one carbonated using the burst carbonation method.

| METHODS |

With the goal of making sure any differences were easily discernible, I designed a Kölsch recipe with a small touch of rye malt for added character.

Reminisce

I started my brew day by collecting RO water, adjusting it to my desired profile, then flipping the switch on my controller to get it heating up, after which I weighed out and milled the grain.

With the water properly heated, I mashed in then checked to ensure it was at my target temperature.

I let the mash rest for 60 minutes, returning every 15 minutes to give it a brief stir.

While waiting on the mash to finish, I prepared the kettle hop additions.

Once the mash step was complete, I collected the sweet wort in my kettle and brought it to a boil, adding hops at the times listed in the recipe.

When the 30 minute boil was finished, I quickly chilled the wort with my IC.

A refractometer reading showed the wort was right at my intended OG.

The chilled wort was then evenly split between two fermentation vessels.

Next, I used my glycol unit to finish chilling the worts to my desired fermentation temperature of 60°F/16°C before pitching a single pouch of Imperial Yeast G03 Dieter into each.

After a week, fermentation activity had dwindled in both beers so I took hydrometer measurements showing they were at the same FG.

I then cold crashed the beers overnight before pressure transferring them to CO2 purged kegs.

At this point, the kegs were placed next to each other in my keezer where one was placed on gas at 15 psi while the other was hit with 1 psi to keep the lid seated; after 10 days, I proceeded to burst carbonate the latter by increasing the pressure to 50 psi and leaving it alone for 15 hours, after which I purged the gas from the keg and set the pressure to 15 psi. I let both beers condition at the same pressure for 3 days before they were ready for evaluation.

| RESULTS | 

Due to social distancing practices as a result of the COVID-19 pandemic, data for this xBmt was unable to be collected in our typical manner. As such, temporary adaptations were made involving the author completing multiple semi-blind triangle tests in as unbiased a way as possible.

Utilizing 4 opaque cups of the same color where 2 were inconspicuously marked, one set was filled with the the beer carbonated using the set-and-forget method while the other set was filled with the burst carbonated beer. For each triangle test, 3 of the 4 cups were indiscriminately selected, thus randomizing which beer was the unique sample for each trial. Following each attempt, I noted whether I was correct in identifying the unique sample. Out of the 10 semi-blind triangle tests I completed, I needed to identify the unique sample at least 7 times (p<0.05) in order to reach statistical significance. In the end, I correctly identified the unique sample 5 times (p=0.21), indicating my inability to reliably distinguish a Kölsch-style beer that was carbonated at 15 psi over 2 weeks from one that was burst carbonated at 50 psi for 15 hours.

As is often the case, I initially thought I perceived a slight difference between these beers, but when blinded, I realized bias was more than likely at play. I really enjoyed this beer and felt the small dose of rye malt contributed a pleasant mouthfeel.

| DISCUSSION |

The ability to force carbonate rather than naturally condition beer is viewed as a huge convenience for many brewers, in large part because it can decrease the time it takes for a batch to be ready to drink. Even when using the set-and-forget method, a beer can be fully carbonated in under 2 weeks, though with burst carbonation, that time can be reduced to under a day. Countering claims that such rapid carbonation has a perceptible impact, I was unable to reliably distinguish a Kölsch that was carbonated at 15 psi over 2 weeks from one that was burst carbonated at 50 psi for just 15 hours.

There’s no denying that carbonic acid, which is responsible for the “bite” imparted by carbonation, exists in beer, but these results along with those from past xBmts seem to suggest its presence is perceptibly similar regardless of the carbonation method used. Another belief held by some is that the set-and-forget method results in finer bubbles, which leads to a more pleasant mouthfeel and higher quality foam; however, that was not the case in this xBmt, as I couldn’t tell them apart once in my mouth, and the burst carbonated beer consistently had better head.

I’m not necessarily the most impatient person and am willing to wait when I need to, but I do enjoy being able to drink nicely carbonated beer the day after kegging it. Given my numerous past experiences as well as the results of this xBmt, I’m even more convinced that burst carbonation is a valid approach for carbonating beer and have no plans to change what has worked so well for me over the years.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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