[Easy Guide] What is Pressurized Fermentation in Beer?

By Simon in Beer Brewing

Quality beer is defined by two main processes: fermentation and carbonation. If you’re exploring new fermentation methods, you may have heard about pressurized fermentation. What is this method, and how can it be used to make beer?

Pressurized fermentation in beer occurs inside a pressurized, sealed vessel with no outlet for carbon dioxide. As carbon dioxide continues to build up during the fermentation process, the beer reabsorbs the carbon dioxide and becomes carbonated.

This article takes a closer look at the pressurized fermentation process, examines the many advantages of this method, weighs the drawbacks, and explains the best way to approach pressurized fermentation at home.

The Importance of Pressurized Fermentation

Besides being an alternative means of carbonation, pressurized fermentation offers some distinct advantages and benefits.

Eliminates many of the unwanted flavors that develop during fermentation. Pressurized fermentation limits esters, which produce fruity tastes and smells in a brew. Excessive esters make a brew taste like solvent. It also eliminates the development of diacetyl.
Allows beer brewers to ferment at higher temperatures without damaging the yeast or its flavor. Hotter fermentation tends to create unwanted flavors. However, pressurized fermentation methods eliminate these tastes.
Eliminates the need to transfer between vessels. Transferring creates the possibility of unwanted oxidation, which is responsible for the undesirable, papery flavor in brews. Because pressurized fermentation takes place entirely in one fully sealed vessel, the process prevents external contaminants from entering your beer and ruining the flavor or causing infection. It’s more sanitary, too.
Allows you to serve beer directly from a keg. With pressurized fermentation, carbonation processes complete along with fermentation.
Eliminates the need to add carbon dioxide in the secondary vessel. Conventional fermentation allows the carbon dioxide to escape, and as a result, not enough of the gas remains for proper carbonation.
Makes brewing faster. Pressurized fermentation allows you to finish and enjoy your beer much quicker. Since the process creates its own carbon dioxide, pressurized fermentation completely eliminates the need for gas.
Saves you money. Pressurized fermentation saves you money since you only need one container versus two vessels and siphoning equipment. Additionally, you’ll be spared potential trips to procure more carbon dioxide.
Preserves hop flavors. Conventional fermentation and carbon dioxide production leach hop oils from a brew. Pressurized fermentation preserves the hop oils and, as a result, the hoppy taste.
Allows you to brew more beer in a smaller vessel. The process produces small levels of Krausen, the foam that develops on the surface of fermented beers. This means you’ll require less headspace in your fermenter.

For more information on fermentation, the following video discusses how long fermentation takes for beer:

Beers Best Suited to Pressurized Fermentation

German brewing relies on pressurized fermentation to create carbonation. To ensure quality control over brewing processes, Germany’s purity laws do not allow carbon dioxide to be mixed into the brews. As a result, German brewers rely entirely on pressurized fermentation to carbonate their beer, and many German-style beers benefit from this method.

Ales and lagers perform well under pressurized fermentation. In fact, pressurized fermentation can reduce a lager’s production time.

Lagers brewed at higher temperatures than normal and under pressure finish exponentially faster than those fermented by conventional means.

Additionally, high temperature and pressure fermentation stifle unsought esters, creating a particularly clean and clear brew.

Ales need lower pressure levels to succeed. High pressures often cause yeast growth issues.

Disadvantages of Pressurized Fermentation

While pressurized fermentation has many advantages, it’s important to be wary of the potential drawbacks.

Unhealthy fermentations. Pressurized fermentation sometimes stresses yeast which can cause unhealthy fermentations. Higher pressure fermentations can lead to lower yeast growth, which causes under-attenuation.
Suppressed ester development. Some beer styles benefit from the presence of esters. Hefeweizens, witbiers, and IPAs all need the flavors esters provide to taste complete. However, pressurized fermentation suppresses ester development, removing the desired fruity flavors from the flavor profile.
Difficulty bottling. Pressure-fermented beers are trickier to bottle. Because the brew is already fermented, you’ll need a counter-pressure bottle filler to maintain those delicious bubbles.

Brewers who dry hop need to be cautious of pressurized fermentation. Dry hopping pressurized brews often cause a volcanic chemical reaction.

How To Pressurize Ferment Your Beer

If you’ve decided to try pressurized fermentation, you’ll need to focus on two major steps: choosing a container and setting the pressure.

1. Select a Container

You’ll need a designated pressurized fermentation vessel. These containers are designed specifically to facilitate pressurized fermentation. These vessels cannot be made of glass, as pressure will shatter the glass, and you will lose your entire brew.

There are several options on the market for those looking for a pressure-rated fermenter intended specifically for home brewing. However, if you aren’t prepared to invest money in a special container, you can repurpose corny kegs that are rated for up to 60 PSI. These affordable 5-gallon vessels are the best option for DIY pressurized fermentation.

2. Set the Pressure

In addition to a pressurized fermentation vessel, you’ll need a spunding valve. This fail-safe device allows you to set the desired pressure value. If the brew exceeds it, the valve releases pent-up carbon dioxide to ensure the brew doesn’t get over-pressurized.

Two major factors impact the correct pressure for your beer: the best pressure to encourage yeast growth and how much pressure your container can manage.

Different yeast strains have different needs and tolerances, so familiarize yourself with your ingredient. However, generally speaking, yeast stops growing at 37 PSI.

Trial and error is the best approach to finding your ideal pressure. Start low, and work your way up. Many brewers site 10 to 12 PSI as the perfect pressure but never exceed 15 PSI.

Conclusion

Pressurized fermentation allows brewers to produce good beer faster. By eliminating the need for secondary containers and adding carbon dioxide, the process saves money and time while still maintaining a superior taste.

The method isn’t ideal for every beer type and should be approached carefully. This article provides you with the foundational knowledge to determine if pressurized fermentation is right for you and your homebrew.