White coating on sauerkraut: Mold or healthy fermentation?

Don't throw away sauerkraut if you notice a white coating on it. First, take a close look at it. It's highly likely that the coating covering the sauerkraut is not mold but rather an indication of successful fermentation.

It may cause concern because it resembles mold, and as we know, we shouldn't eat moldy products, even if we remove the harmful coating. Usually, however, the white layer found on sauerkraut, cucumbers, or homemade vinegar is a fermentation film that indicates the fermentation process is going well.

The fermentation film forms as a result of the natural lactic acid fermentation process, which occurs under the influence of lactic acid bacteria. We could say it's a byproduct of fermentation that forms a thin layer over the sauerkraut. It's safe for preserved foods and our health, so we don't need to worry about it. However, it is recommended to remove the fermentation film from the surface of the sauerkraut or stir it in, as it could lead to quicker spoilage if left untouched.

To some people, a fermentation film might look like mold. And this should be a cause for concern. Distinguishing one from the other might seem challenging, but it's enough to know what to look for to determine whether the sauerkraut is covered in mold or a fermentation film.

Firstly, mold appears in clumps, resembling fur. It also uses various colors – from light to gray, blue, and orange. It's more problematic if we're dealing with white mold. Then, it can be distinguished from the fermentation film by its texture, as mold is not homogenous, whereas the fermentation film is milky white and uniform. Additionally, moldy sauerkraut develops a characteristic, musty smell. On the other hand, if the sauerkraut is sour and salty and has a pleasant aroma, it is certainly safe to eat.