I'm a newcomer to the world of lacto-fermentation.

I've previously made my own sauerkraut with great success, and thought to dip into the unknown and try lacto-fermenting onions, carrots, and beans.

I did so by cleaning the jar with boiling water, wash the vegetables, adding water, salt, and some brine left over from the sauerkraut ferment.

It's has been 2 to 3 weeks when I check my carrot ferment today. There are quite some white growth on top. It has a faint alcohol-like smell. Does this mean it has gone off and unsafe to continue?

EDIT: Browsing the internet, seems to be either mould or yeast. I don't want to chance it so I am disposing it.

Picture of white blobby things growing atop the ferment

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3 Answers 3


Throw it away and start again. How much of that liquid was bribe? Something went wrong. It looks like you added too much liquid. You only need enough to cover your vegetables. I would use 5% by weight of salt for this type of pickling. For example, if you use 100 pounds of carrots, then add 5 pounds of salt.

Don’t give up! Try again


If it was me I would start over. When in doubt throw it out. For vegetables, I weigh the vegetables, do my math percentage for the salt then weigh the salt and put in the jar first with a bit of filtered water. Then, I add the veg, then fill it up with the filtered water. This way I know that my salt is 100% correct. I used to do it by tablespoon and quart. I decided that if I didn't use all the water, then I also wasn't actually using the right amount of salt. that is why I switched to adding that salt in the jar first with a bit of water. I do two percent on my sauerkraut and Three percent on my vegetables. I do not make a brine for sauerkraut, I let it make the brine. I always know my salt is right based on the weight. If you don't have one get you a kitchen scale that you can tare and weigh your vegetables and your salt. Do some reading and research decide on your salt percentages.


tdewtx's comment "when in doubt throw it out" is a good rule of thumb. If you're not sure, it's always better to start over.

Most likely explanation

But...there's a good chance that this is a harmless yeast colony. It's hard to tell from the small pictures, but this kind of thing is extremely common in fermentation and is referred to as "kahm."

You can read a description here. Sandor Katz, a lacto-fermentation guru, has a great 2-ish minute explainer (with a minor promotional comment at the end). And there are lots of "delightful" kahm pictures here.

Why this is likely

There are two reasons to think this is just kahm.

  1. In my experience, carrots are more likely to develop kahm than most other ferments. I assume this is due to their high sugar content.
  2. You mentioned a faint alcohol smell. Often when people say this, they mean beer or wine, i.e., yeast.

What to do next time

To address this if it happens in the future, never let a ferment run 2-3 weeks before checking it. Especially for the first couple of weeks, I check every day or two. That way I can scrape off anything unpleasant before it becomes widespread.

When kahm is widespread, I throw out the ferment—not for safety reasons, but because it tends to impart a yeasty flavor to the vegetables. But when there's just a little at a time, as long as it's not actually in contact with the submerged vegetables, and if I'm confident it's yeast, I scrape it off and continue.

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