If an unexpected flavor of green apples or hard cider has presented itself in your homebrew, you likely have an acetaldehyde problem on your hands. Now that you know what it is, how do you get rid of it?
If your yeast is dormant or dying, you may need to turn to the German art of krausening. This will allow you to rid your brew of acetaldehyde by introducing fresh, healthy yeast to a beer in the middle of fermentation.
The presence of acetaldehyde in homebrew typically has one of three root causes: 1. The beer has not fully fermented 2. The yeast is unhealthy and underperforming 3. Over-oxidation has occurred, typically during bottling
Its flavor is most commonly compared to the sweet tartness of green apple. In some cases, it may make your beer taste more like a very dry cider.
In high enough concentrations, acetaldehyde will cause your homebrew to present a green apple odor in addition to the appley flavor.
In some cases, simply conditioning your beer longer will resolve the issue. If your airlock stops bubbling and the off-flavors of acetaldehyde are still presenting themselves, the next thing to try is a German technique called krausening.
Maintaining a high standard of sanitation will help prevent acetaldehyde, and a host of other unwanted guests, from showing up in your homebrew.
- Allow your homebrew to finish conditioning - Use healthy yeast in your homebrew (and use the right amount!) - Ferment your homebrew at a slightly higher temperature -Avoid aeration as soon as fermentation begin -Don’t introduce oxygen to your homebrew during bottling