Fermentor VS Fermenter: What’s the Difference?

Home brewing can be an addictive past time. The process of beer making is fascinating and experimenting with different recipes in an effort to find the “perfect brew” is very enjoyable.

Of course, home brewing can also be frustration at times, particularly if a brew goes bad due to incorrect measurements, poor ingredients, or temperature exposure. 

Another frustrating aspect of home brewing is all of the jargon, slang, and careful intelligible waffle that comes with the past time. There are dozens of technical words along with countless nicknames and colloquialisms for brewing equipment, which can lead to confusion.

Two of the most commonly confused and misunderstood terms are fermentor and fermenter. Given that they sound similar and are both related to fermentation, it’s no wonder. Here are the definitions and difference between these terms.

What Is A Fermenter?

Fermenter has two definitions. The first definition for fermenter is any agent or substance that causes fermentation. In the world of home brewing, this is usually a bacterium like mold or yeast, or an enzyme.

When home brewing beer, the most frequently used fermenter is yeast, which promotes the anaerobic (oxygen-free) conversion of sugar to ethyl alcohol and carbon dioxide. In slightly simpler terms, the yeast cells eat and metabolize the sugars found in the wort, producing alcohol and CO2.

The second definition for fermenter is “an apparatus that maintains optimal conditions for the growth of microorganisms, used in large-scale fermentation and in the commercial production of antibiotics and hormones.” Source.

In the world of home brewing, the types of fermenter apparatus most commonly used are buckets, carboys, conicals, and corny kegs.

What Is A Fermentor?

A fermentor is “an apparatus that maintains optimal conditions for the growth of microorganisms, used in large-scale fermentation and in the commercial production of antibiotics and hormones.” In other words, a bucket, carboy, conicals, or corny keg!

As you may have realized, the definition of fermentor is identical to the second definition of fermenter! It’s no wonder the terms are sometimes confused and used interchangeably.

Fermentor vs Fermenter

So, a fermenter can mean either the ingredients that trigger fermentation or a fermentation apparatus. A fermentor is only be used to refer to the apparatus itself.

So, if you are writing an email, blog post, or manifesto about home brewing, remember to use the appropriate spelling. If you want to avoid confusion, it’s usually best to use fermenter when referring to yeast or other active agents and fermentor when referring to fermentation vessels.

Two different pictures of homebrew fermenting. Text in-between the two pictures reads fermentor vs fermenter.