How to Get Rid of Acetaldehyde in Beer
During the brewing process, off flavors can arise in all shapes and sizes, metaphorically of course. From band-aids and baby vomit to buttered popcorn and green apples, off flavors will typically work themselves out of beer, as long as all sanitation measures have been followed, but sometimes you don’t know just what to do during brewing to allow that process to play itself out.
This is certainly true of acetaldehyde, so if you’ve been wondering how to get rid of acetaldehyde in beer, you’ve come to the right place.
What Is Acetaldehyde?
Acetaldehyde is a naturally occurring compound found in many foods and even in the human body. It is most often found in nature as a clear liquid with a strong, fruity odor. In really high concentrations, this chemical can make breathing difficult when encountered as a smoke – like cigarette smoke or burning wood – and it can be dangerous to the human body – like splashed in the eyes in chemical factories or drunk in large quantities in alcohol, milk, or fruit juice.
Again, the concentrations have to be really high. You likely won’t be able to drink enough fruit juice milk to get acetaldehyde poisoning.
When you drink alcohol, however, you are encountering both small amounts of the acetaldehyde found there, and your body will produce acetaldehyde when it ingests alcohol, so you have a larger concentration.
When your body encounters this chemical, your liver will turn acetaldehyde into acid, and your blood membranes can be damaged. It is also part of what causes a hangover, a sped-up heartbeat, and even memory damage.
In small doses, however, your body knows how to filter what it sees as poison and create a detoxification.
Acetaldehyde is known for tasting and smelling like green apples or even dry cider.
How Does Acetaldehyde Get into Beer?
Acetaldehyde is a well-known off-flavor in beer that is created during fermentation.
When yeast is first introduced into wort, as it consumes the sugars, it expels an excess of acetaldehyde as a metabolic release. The chemical is then mopped up during the rest of the fermentation process, as long as that process is allowed to come to completion.
The number one way this off flavor is found in beer is through the cutting off of the fermentation process. The beer is racked too quickly and then not allowed secondary fermentation.
The longer the beer sits with fresh, young yeast cells, which are continually being produced through natural fermentation and asexual reproduction, the more acetaldehyde will be cleaned up.
Oxygenation is another way excess acetaldehyde can be created, if it occurs after fermentation has begun.
Another way this chemical can get into your beer is through too many old yeast cells allowed to sit in the beer. Old yeast cells can experience a breakdown of their cell walls and essentially explode inside of the beer, releasing extra acetaldehyde into the beer.
Finally, you can get too much acetaldehyde into beer through unsanitary practices, like cracks in brewing equipment or un-sanitized surfaces that allow wild yeast and bacteria to thrive.
How to Avoid Acetaldehyde in Beer
In terms of avoiding excessive acetaldehyde in beer, you can simply be sure you allow for the full fermentation process to complete.
First, be sure your yeast cells are not only alive but also healthy and thriving. You can accomplish this with a simple chemical test using affordable equipment that will tell you not only how vital but also how viable your yeast cells are.
Next, make certain that your wort is thoroughly oxygenated before the yeast is added. You can oxygenate your wort by agitating it prior to fermentation.
Fully oxygenated wort will ensure your yeast thrive while fermenting and reproduce adequately, which will allow you to get rid of dead yeast cells and encourage the young and healthy ones.
Then, be sure you pitch yeast into a closed, airtight vessel so no more oxygen gets into the wort once fermentation has begun.
During fermentation, it is important to watch the krausening, or the foamy crust that forms to let you know approximately which part of fermentation is taking place along the way.
You should not stop fermentation or interfere with it, aside from taking gravity readings, until the krausen has peaked and died back down, which signals the completion of primary fermentation.
Finally, be sure to remove all sediment from your beer, including old yeast cells in the trub, effectively “racking” beer and then allowing it to undergo secondary fermentation.
It is during secondary fermentation that the remaining young and healthy yeast cells will clean up after themselves, mopping up off flavors, including acetaldehyde.
How to Get Rid of Acetaldehyde in Beer
The most important step to get rid of acetaldehyde in beer once it has been created is the krausening, the racking, and the secondary fermentation.
It is through these natural processes that virtually all off flavors can be eliminated, including acetaldehdye.
Remember, this chemical is naturally occurring rather than a freak accident of some sort, in most cases.
Once you know you have done your due diligence in terms of sanitation and oxygenation, as well as keeping up young and healthy yeast cells, you have done all you can to prevent unnecessary production of acetaldehyde.
Now, it is simply a matter of allowing nature to take its course. Brewing is meant to be a process that flows from one step to the next, rather than one that is forced. It is typically only when we try to speed up processes like fermentation that we encounter real trouble.
As a brewer, one of the greatest lessons we learn is to be patient and trust the process.
Cheers!
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Sources:
- https://www.stonebrewing.com/blog/stochasticity-lab/2014/guide-flavors-acetaldehyde#ageGatePassed
- https://beerandbrewing.com/off-flavor-of-the-week-acetaldehyde/
- https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1971.tb03405.x
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