4 Simple Ways to Prevent Mold on Homemade Sauerkraut

Having problems with mold on homemade sauerkraut? There are 4 easy ways to keep mold from ruining all your work. Read this before you make another batch!

Having problems with mold on homemade sauerkraut?  I just hate opening up a jar of freshly fermented sauerkraut only to discover mold on the top.  Has that ever happened to you?  I would rather be safe than sorry, so the whole batch goes in the trash and I have to start all over again.  Not only is it a complete waste of money, but it is a complete waste of time too!

Fortunately over the years, I have discovered a few solutions that really help keep mold from taking over and ruining your batch of sauerkraut.  I make at least 1 batch of  lacto-fermented sauerkraut per month and since I started implementing the following 4 steps, I haven’t lost a single one to mold! 

These steps don’t cost a lot of money or take a lot of time to implement, but they can make a HUGE difference in the quality of your finished sauerkraut.

Here are 4 simple steps you can take to help prevent mold on homemade sauerkraut.

Sterilize your mason jar or crock that you use for fermenting the kraut.

Granite Ware Water Bath CannerGranite Ware Water Bath Canner

Although you can buy commercial sanitizing products meant for home brewers, I have found that it is just as easy to use boiling water to kill any mold spores.

I typically add my mason jars to a large canning pot, cover with water, then bring it to a boil.  Allow it to boil for 10 minutes than place in a drainer to air dry.

This process should kill any of the nasty bacteria that might have taken up residence on the walls of your mason jars.



Ensure that all the shredded cabbage is submersed in the brine.

Pickle Weights for Wide Mouth JarsPickle Weights for Wide Mouth Jars

Nearly all my problems with mold on homemade sauerkraut can be attributed to some of the cabbage poking up above the brine solution.  The salt in the brine solution helps prevent any nasty stuff from growing while the lactobacillus population grows and does its work on the cabbage. (Lactobacillus is the good bacteria that helps preserve the cabbage and gives sauerkraut its yummy sour flavor.)  The brine solution however can’t protect anything that is sticking up above it.

One thing I do to keep all the cabbage down in the brine solution is to use pickle weights.  Pickle weights are small glass discs that keep all the cabbage bits down in the liquid where it belongs.  (Quick Tip: Make sure you get pickle weights that are made for wide mouth mason jars.)

Using pickle weights is easy.  After your cabbage is submersed in the brine, you just add the weights to the top before you close the jars.  They are just the right size to keep all the little floaty bits under the brine.



Use a special mason jar lid fitted with an airlock.

Perfect Pickler Fermenting KitPerfect Pickler Fermenting Kit

The bacteria which produce the sour flavor characteristic of sauerkraut thrive under anaerobic conditions.  That means they thrive in an environment where no oxygen is present.  It can be difficult to achieve that if you are fermenting your homemade sauerkraut in a traditional mason jar with the 2 part lids.  Mold present in the air can be given a chance to grow if your sauerkraut is exposed to too much air.

One way I help provide the ideal fermenting environment for my sauerkraut is to use a plastic mason jar lid with an airlock. The airlock seals out air but allows the gases created during fermentation to escape.  Besides helping to prevent mold, another benefit of using an airlock is that you don’t get any of the smells that are associated with crock fermentation.

There are many brands of airlock lids out there but the one I use is the Perfect Pickler.  I got their starter kit which came with a special lid that fits mason jars, an airlock, sea salt, an instruction/recipe book, and an informational DVD.  I liked that it included everything I needed to get started.  If you don’t need all the extras though, you can get the airlock lids separately.



Use a starter culture.  

Caldwell's Vegetable Starter CultureCaldwell’s Vegetable Starter Culture

I have often made sauerkraut successfully only using the Lactobacillus bacteria that is naturally present on the cabbage.  However, if you are having problems with mold, I recommend using a starter culture to make sure your lactobacillus colony is strong and can keep all the bad bacteria at bay.

If you want to try a sauerkraut starter culture, I recommend Caldwell’s.  They are an established company that has spent years researching the fermentation process.  Caldwell’s has developed the perfect ratio of bacterial strains that gives you great results every time.



Pin this post on preventing mold on homemade sauerkraut for later:

Having problems with mold on homemade sauerkraut? There are 4 easy ways to keep mold from ruining all your work. Read this before you make another batch!

Don’t let mold on homemade sauerkraut ruin another batch!  With these 4 simple solutions, you won’t have to throw out moldy sauerkraut ever again!


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