Tips To Prevent Beer Loss During Fermentation

When homebrew beer is fermenting, it will naturally begin to bubble and foam on the surface. This is a sign that the yeast is reacting to the sugars, converting them into alcohol. If there’s no foam on the surface of your beer, something is wrong. However, an excessive amount of top foam may send some of the beer spilling over the sides. It’s not uncommon for first-time brewers to lose a fair amount of their beer during the fermentation stage.

If you’re struggling to brew a decent batch of beer without losing an excessive amount during fermentation, you should try tweaking your technique and/or recipe. There are some small steps brewers can take to reduce boilover.

Homebrew beer during fermentation (notice the top foam): photo by geoffeg.

Pros and Cons of Anti-Foaming Agents

One technique that many brewers use to reduce beer loss during fermentation is adding an anti-foaming agent. There are liquid-based products designed specifically for the reduction of beer foam. While they are certainly effective at reducing beer loss, they may also affect the flavor and overall carbonation of your brew.

Personally, I wouldn’t recommend using an anti-foaming agent. It’s only a temporary solution that doesn’t solve the underlying problem. And depending on which type of anti-foaming agent you decide to use, it may turn the flavor of your beer. Removing unnecessary contaminants (including anti-foaming agents) will improve the quality of your beer.

Beer foaming: photo by soapbeard.

Use a Larger Container

The easiest way to prevent beer loss during fermentation is to simply use a larger container. For instance, if you intend on brewing a 5-gallon batch of beer, perhaps you can use a 6-gallon container. The additional space allows the foam to rise without spilling over.

I’ve also heard of brewers placing a loose-fitting top over the larger container to help control the foam. The top will still rise as the foam develops, but it will help prevent the beer from spilling over if it rises too high. You don’t have to screw the lid on your container, but instead let it sit on the top of your beer. This allows the lid to rise and lower depending on the foam production levels.

Should I Leave The Foam?

It’s usually best to discard the foam created during fermentation. Leaving small amounts in your brew is perfectly fine, but too much will affect the flavor and quality of the beer.