Fermentation FAQs

Don’t forget to read the resources too!

Before Fermenting


What is fermentation anyway?

There is a whole PDF dedicated to more info about the wonders of fermenting. The short of it is that fermentation is the digestion of carbohydrates by beneficial bacteria in a given product. ie. the digestion of lactose in milk by many beneficial bacteria to produce yogurt. Purification is the digestion of proteins by pathogenic bacteria.

What about histamine intolerance and consuming sauerkraut?

I have investigated this question and here is a little write up.

Do I have to sterilise the jar/crock I am using?

No, the rule of wild fermentation is be be clean but not sterile. You don’t want to kill off the beneficial bacteria that are going to produce the

Should I wash my cabbage?

No, only rise off any dirt or hangers on (ie. slugs. You might get those with organic cabbage) that might be there. You shouldn’t wash the whole cabbage too thoroughly, the bacteria that you’re going to be farming in your ferment come in on the cabbage and you don’t want to loose them!

During the preparation of sauerkraut


I want to use other vegetables. When do I add them to the cabbage how should I cut them up?

At the salting stage. Add salt and anything extra you want to use to the cabbage and then mix and schmoosh.

For most veggies that you might be adding (ie. carrots, beets, radish, turnip, ginger, turmeric) I personally think that it’s best to grate these with a regular grater.

How much salt should I use?

There is a whole PDF about salt, but the fast facts: aim for 1-2% of the weight of your cabbage as salt in grams, ie. if you have 500g of cabbage, use 5-10gms of salt.

Great, but I didn’t weigh my cabbage before I chopped it up…

Ok, a good rule of thumb is a level tablespoon (fine salt) or a rounded tablespoon (salt flakes) for a whole large cabbage. That should be enough. If you’re having trouble getting the brine to come out of the cabbage, add a little more. Watch out, you can over do salt easily.

What sort of salt should I use?

There is a whole PDF about salt, but fast facts: flakes or fine salt, no rock salt (unless you have it in a grinder). Unrefined mineral salt is nicer. Your average table salt will do though. CERES Fair Food sell lovely Mount Zero salt and Murray River salt flakes

What if I can’t get enough brine out of my cabbage?

Add a little more salt, or leave the salted cabbage to sit for 10-3o mins before attempting to massage the brine out of it again. Also, here is a nice sauerkraut flow chart to help answer this question.

Why do I have to leave space at the top of my jar?

Leave enough room for you brine to rise in the first stage of fermentation  Carbon dioxide being released by the bacteria (mainly Leuconostoc mesenteroides) need to push their way up and out. They also cause the brine to leak out of your sealed jar. These bacteria are most active during the first 3 days of fermentation. There will be less bubbles and brine activity after these first few days.

Fermentation stage


What bacteria are in my sauerkraut?

This is from a Applied and Environmental Microbiology journal article

[prevailing species of lactic acid bacteria in sauerkraut are], Leuconostoc mesenteroides, Lactobacillus plantarum, Pediococcus pentosaceus, and Lactobacillus brevisLeuconostoc citreum, Leuconostoc argentinum, Lactobacillus paraplantarum, Lactobacillus coryniformis, and Weissellas as well as Leuconostoc fallax.

How long do you ferment the vegetables? I wish I had an easy answer to this question. Sour flavor—from lactic acid—develops over time. Longer fermentation translates to tangier flavor. This happens more quickly in warm temperatures than in cool ones. Many people, however, prefer the flavor of a mild ferment to that of a strongly acidic one. I would recommend 4 weeks, but if you can’t wait, 2 weeks is fine.

What temperature should I ferment my sauerkraut at?

Room temperature is adequate at this time of year (mid-spring). The best krauting temperature is between 17-22 degrees. Too hot and the sauerkraut might go soft (it ferments too quickly) or might be more prone to mould.

Should I “burp” my jar as it’s fermenting.

No! If the pressure in the jar get too much, the brine might overflow a bit (just keep the jar in a bowl) but you don’t want any extra air in the jar. Once you have closed that jar on your ferment, try not to open it until it’s time to eat. Only open the jar if the brine level has changed so much that the cabbage is no longer covered. If this happens, push the cabbage down again, make sure it’s submerged, weigh it down with a snap-lock bag full of water, a glass, small jar or shot glass and reseal the jar. A recycled jar should not seal well enough to warrant worrying about “exploding jars”.

Do I leave the lid on all the way through fermentation?

Yes. See FAQ directly above.

Will my jar explode?

No. really, there is such a tiny chance of this if you are using any of the recommended jars. The seal won’t be strong enough to warrant such a buildup of gases.

Brine is bubbly and spilling out the top of my sealed jar

This is a good sign! Carbon dioxide being released by the bacteria (mainly Leuconostoc mesenteroides) need to push their way up and out. They also cause the brine to leak out of your sealed jar. These bacteria are most active during the first 3 days of fermentation. There will be less bubbles and brine activity after these first few days.

My brine is cloudy…

Cloudy brine can be fine and can be a sign of things going wrong. Don’t flip out yet!  Some say it is caused by dead cell walls from the vegetables floating around. Others say it is from iodine or anti-caking agents found in some salts (particularly if you used regular table salt). The cloudy brine may settle out and form a white ring at the bottom of your jar. When it comes to eating the sauerkraut, use your sense… if it smells off/tastes off, it probably was the wrong end of cloudy.

My brine is slimy…

This may be because of something you’ve added to your cabbage. Did you use beets or carrots? The high sugar content of some veggies invites in unwanted microorganisms that prefer the high sugar vegetables. Again, use your sense… if it smells off/tastes off, it probably was the wrong end of slimy.

To help prevent this next time: Make sure you use only about 25% other vegetables in your sauerkraut, ferment sauerkraut with higher-sugar veggies for 14 days only, and make sure the ferment stays in a temperature between 17-22 degrees.

There is a white layer on the surface of my brine/sauerkraut

(from www.makesauerkraut.com) A whitish velvety or powdery layer floating of the top is not mold, but rather a layer of yeast called Kahm yeast. It can look scary and unpleasant and even smell a little strong, but it is not a harmful thing. Although harmless, Kahm yeast is something you don’t want to let overgrow since it affects the flavor of what you are fermenting. Remove as much Kahm yeast as you can from your ferment. Keep vegetables submerged in brine and container sealed.

For mould on Kahm yeast, see the good folks at cultures for health http://www.culturesforhealth.com/learn/natural-fermentation/white-film-cultured-vegetables-mold/

The cabbage at the top of my jar has discoloured…

This is probably because it has oxidize (it has been exposed to air). Monitor daily for any signs that mould might be developing. Is the brine still covering the cabbage? Make sure it is! If not, open your jar and push the cabbage under the brine again and weigh it down, recap and continue to ferment.

I have mould on the surface of my sauerkraut…

Ok, mould. What you do is up to you. Mould is an aerobic organism, that is, it needs air to live. Under the brine of the sauerkraut, the mould can’t thrive, both because it is an anaerobic environment (without air) and because of the salinity and acidity (the bacteria in the sauerkraut fermentation process are lactic-acid creating.) Therefore the cabbage under the brine is not affected by surface mould.  You can take off the mould layer and still eat the sauerkraut underneath. I have done this many times. BUT IT IS UP TO YOU. Use your judgement and senses. If it’s not good, it’s not good.

Why did my sauerkraut go mouldy?

It could be because it fermented to hot, or there was too much air in the the ferment (usually the mould form on any floating things that are exposed to the air on the surface on the brine, or anything above the brine level.) Mould is aerobic, whereas lactic acid fermenting bacteria are anaerobic.

My finished sauerkraut is too salty

Sometimes too much salt gets mixed into our ferment. To remedy this you can:

-Mix sauerkraut with lettuce (when you serve it) or stir into foods to “dilute” the saltiness

-Ferment for a longer time period. The longer you ferment, the less salty the ferment becomes.

-Measure salt and weigh vegetables to insure a 2% brine next time!


Storage stage


How do I store/keep my sauerkraut?

As soon as you’ve reached the point where your sauerkraut has fermented enough to your palate (if that’s 2 weeks or 4 or longer), put the sauerkraut in the fridge. Make sure the sauerkraut stays at least moistened, if not covered in its brine for the longest storage time. This might mean that you need to put it into smaller and smaller jars as you consume your ferment, depending on how fast you eat it. I eat about a jar a week, so I don’t have to think much about storing it optimally.

How long does sauerkraut keep for?

This sauerkraut is a fermented product so it will keep for at least two months and often longer if kept refrigerated. As long as it still tastes and smells good to eat, it will be. If you like, you can transfer the sauerkraut to a smaller container for longer storage.


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