What Does Fermentation Smell Like?

If you buy something through a link in our posts, we may get a small share of the sale.

Fermentation is the key to the beer-making process. It is the process that breaks down the sugars in food, creating alcohol and carbon dioxide as byproducts. Fermentation has been used for centuries to make beer and other alcoholic beverages. Now, you may be wondering, what does fermentation smell like?

What Does Fermentation Smell Like?

The smell of fermentation is often described as “yeasty” or “bread-like.” This is because fermentation creates carbon dioxide, which produces a yeasty smell. The scent of fermentation can also be described as “fruity,” “sour,” or “reminiscent of vinegar,” depending on the type of food that is being fermented. It is also an indication that the process is going on well.

An image of a woman drinking beer

An excellent way to get an idea of what fermentation smells like is to think about the smell of beer or bread. Both of these foods go through a fermentation process, and they have a distinct smell that is different from other foods. If you have ever been near a brewery or a bakery, you will know what I am talking about.

The smell of fermentation is sometimes compared to the smell of vinegar. This is because vinegar is also a product of fermentation. When food is fermented, the sugars in the food are broken down into alcohol and carbon dioxide, creating vinegar.

How Fermentation Works

Fermentation is the process of converting sugars into alcohols and carbon dioxide gas–the fizz in beer. This chemical reaction is catalyzed by enzymes that occur naturally in yeast cells. When yeast and sugar are combined in the right proportions and kept at the right temperature, fermentation will occur.

The carbon dioxide gas is produced as a waste product of fermentation. It is produced in such large quantities that it forces the liquid out of the container if it is not vented. The alcohol is produced when the yeast cells consume the sugar molecules and convert them into energy. This process produces the characteristic flavor and smell of fermented foods.

The best vessel to use for fermentation is one that allows the carbon dioxide gas to escape and doesn’t allow oxygen to enter. This is why many people use a mason jar with a loose-fitting lid for fermentation. The lid allows the gas to escape while preventing oxygen from entering and causing the wort( the liquid extracted from the mashing process during beer brewing) to spoil.

Does Homebrewing Beer Smell Bad?

Generally speaking, the smell of fermentation is not bad. Many people find the smell of fermenting beer to be quite pleasant and even sweet. If you are a beer lover, then you have probably noticed the sweet smell of fermentation while standing in line at a brewery or while walking past a bar.

However, there are a few scenarios in which the smell of fermentation can become unpleasant. This could indicate that your brewing process is not going as planned or something has gone wrong. The following are a few of the most common causes of unpleasant fermentation smells:

  • Infection: If your beer has become infected with bacteria, it will likely smell bad. This is the most common cause of unpleasant fermentation smells. The smell could be that of sour milk, vomit, or spoiled meat. If you notice any of these smells, it is best to discard the beer and clean your brewing equipment thoroughly.
  • Off-flavors: If your beer has picked up any off-flavors, it will also likely smell bad. The most common off-flavors are caused by oxidation, which can produce a cardboard-like smell. Other off-flavors include phenolic flavors, which can smell like Band-Aid or disinfectant, and sulfur flavors, which can smell like rotten eggs.
  • Sanitation: If your brewing equipment is not properly sanitized, it can cause your beer to smell bad. The most common sanitation issue is wild yeast contamination, which can cause your beer to smell like bread dough or sourdough. Use a non-rinse sanitizer to clean your brewing equipment to prevent this from happening.
  • Corrosion of the Brewing Vessel: If your brewing vessel is made of metal, it could be corroding. This will cause your beer to smell like metal. To prevent this, clean and sanitize your brewing vessel regularly. You can also use stainless steel or food-grade plastic brewing vessels, which are less likely to corrode.
An image of a person smelling beer

Frequently Asked Questions

Should Fermentation Smell?

Yes, fermentation should smell. The most common fermentation smells are alcohol, bread, and yeast. If you notice any other smells, it is best to investigate the cause and take corrective action.

Why Does My Beer Smell Sweet?

The beer smells sweet because the yeast consumes the sugar and converts it into alcohol. This is a normal part of the fermentation process and is nothing to worry about. Examples of sweet smells are ripe fruits, candy, honey, and molasses.


Fermentation must be done in an oxygen-free environment to prevent the wort from spoiling. This way, the yeast can convert the sugar into alcohol without producing off-flavors hence producing a pleasant smell. Homebrewing beer should not smell bad; if it does, it indicates something has gone wrong.