Fermentation 101: Kombucha and Kraut… after the class

Each month (first Sunday of the month, 5-7pm) we have a hands on class on kraut-making as well as a demo on kombucha brewing. It is an exciting opportunity to see, touch and feel while having someone offer insight on several years of fermentation. It can be daunting to start fermenting if you’ve never done it before but with a little help some of that fear can be abated.

After the class we encourage participants to ask questions, send photographs- anything to help you on your way in your first few batches of ferments. But we thought that we would put some information here on our site to help you along while you get going. This post today will focus on the first portion of the fermentation class: krauting making. We hope to answer many questions about the process as your sauerkraut is fermenting. Of course, as always, if you have any additional questions, feel free to stop by, email us or give us a call with any questions.

Class is over now what?

So you just went home with your first batch of kraut. Where to start?!

You don’t need any fancy tools to make sauerkraut. Sandor Katz believes heartily in using tools that you already have on hand and that is generally what we go with. Having said that, there are many tools that you can utilize to help make you feel a little more comfortable in your fermenting.

  • Weights-

Weights keep your kraut blend submerged in the brine. Weights can come in a variety of styles including ceramic weights, vegetable Weight stones for fermenting crocks 2014cores (we demonstrate in class), large rocks or even a small jar. They all serve the same purpose- keeping your kraut under the brine and healthfully fermenting.

  • Air locks-

Air locks can make things a little simpler because you can be a little less hands-on with your kraut. The air lock serves to release the carbon dioxide that is building in the kraut while fermentation is beginning and continuing. There are a few brands that secure right on to a mason jar if you are working on small batch ferments. If you have to travel or otherwise just don’t pay as much attention to your ferment, airlocks can be very helpful in keeping your batch pretty safe. Even with airlocks brine evaporation occurs, so do check your water levels.

You want to place your sauerkraut in a dry and draft-free place. Remember that it needs to stay at least 5 feet away from any other ferment or cross fermentation will occur and one will inevitably die. The temperature should stay in the 65-75 degree range, anything lower and fermentation will slow or not occur at all. Higher temperatures could speed fermentation, but watch carefully for water levels, the higher the temperature the quicker the water evaporation.

My kraut is overflowing!


As fermentation begins, within the first 24-48 hours you will notice your kraut is overflowing as bubbles begin to start the fermentation process. This is lactic acid releasing from the vegetables causing , hence lacto-fermentation. You will get to a point where you feel like it will never stop overflow, but it will. Be sure to continuously check the water levels in the first week of fermentation. When the first portion of the fermentation slows down, there will be a low water level. Be sure to add more water (brine… 3 parts water, 1 part sea salt) and keep the water level above the kraut. Should you notice the water is low, skim off any kraut that has been exposed to air and add the brine and continue to ferment.


There are various schools of thought on mold. Some people are extremely sensitive to molds (like myself). I try to keep moldmy sauerkraut mold free by consistently checking on it and maintaining a good brine level. Generally I won’t eat kraut that has developed mold because like about 1/3 of the population I have developed a severe reaction to mycotoxins. However, many hardcore fermenters simply say, skim the scum and you are good to go. Sandor Katz himself has a breakdown of the creation of molds in fermentation and how to avoid it here.

The Fermenters Club also has some great info about mold and even a video on skimming.

The bottom line is that you should (in my opion) be cautious about molds, but if there is scum or mold present, it doesn’t necessarily mean your whole batch is done for. Here is a great infographic to give you some guidelines on mold.


How Long?

I think the last question I usually get is “how long do I leave it fermenting?” There are many guides that can give you some ideas on how longtimechart to ferment your kraut. As fermentation continues your kraut changes and develops the flavor. Once your kraut gets that pickly-briney flavor that YOU are happy with, go forth and eat it! If your still a little concerned here is a good graphic that gives you some more detail on the process through time.

For us, we generally let our kraut ferment between 4-6 weeks. Then once we start to eat it… we start a new batch!


I hope that answers some sauerkraut fermenting questions. NEXT: Kombucha… what happens next?

Leave a Reply