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How to make sauerkraut and kimchi safely

Two hands squeezing liquid out of salted cabbage

Safety is often a top concern for home fermenters and can put fermentation wannabes off giving it a go. We get it. Leaving a jar of vegetables on your counter for days if not weeks seems weird and maybe even downright dangerous to the uninitiated. This is why we've made this handy post to help put your mind at ease when making lacto-fermented vegetables like sauerkraut and kimchi at home. We think fermentation should be available to everyone and we don't want anyone to be put off by fearmongering about sauerkraut and kimchi. So, if you follow these straightforward tips you'll be making safe and tasty ferments everytime!

The general principles of safe fermentation do apply to all types of fermented foods, but any specific mention below of salt and lacto-fermentation is specific to fermenting vegetables.

Practice basic food hygiene in the kitchen

To make ferments at home you don't need to invest in expensive kit or fancy cleaning products. Your basic kitchen utensils, an old jar and simple cleaning products will do! The main thing to remember is basic food hygiene, the same way you would whenever you're cooking at home. So, clean hands, surface and equipment are a must. Just wash equipment (including the jar you'll be fermenting in!) in hot soapy water or in the dishwasher before use.

Use at least some salt

Although it is technically possible to make kraut or kimchi with no salt we strongly recommend against it. Salt is needed for several reasons:

  • It helps to inhibit pathogenic and food spoilage microbes

  • It helps to give lactic acid bacteria ( the ones we want to grow!) a competitive advantage

  • It helps keep veg firm and crisp by hardening pectin (a type of fibre) in the veg, reducing the risk of a soggy ferment!

We recommend somewhere between 1.5-2.5% of salt by weight of your vegetables for safety, and ideal taste and texture. Make sure you weigh your salt so you know you’ve added enough to inhibit the growth of microbes that don’t like salt and make sure the salt tolerant lactic acid bacteria we want to grow stand the best chance possible. You can calculate how much salt you need by weighing all the veg you'll be using first and then multiplying that number by the decimal version of the percent salt you'll be using. So, if you're going for 2% salt you'll multiply the weight of your veg by 0.02 - see an example below.

Total weight of veg = 1200g

I wish to use 2% salt, therefore to calculate salt I need to multiply 1200 by 0.02

1200 x 0.02 = 24g

Salt = 24g

Limit oxygen exposure

This is arguably where people go wrong the most and it’s so easy to do. If you’re not keeping a close eye on your kraut or kimchi as it ferments away the top layer of veg can become exposed to air as carbon dioxide gas is produced and pushes the veg up above that top layer of brine. It's really important to check your ferment regularly while it's fermenting. This is primarily to check if the top layer of veg has become pushed up above the brine or if the brine has leaked out of the top of the vessel. If it has this exposes the top layer of veg to air which is the main cause of mould growth in ferments, So we want to make sure there is always liquid covering that top layer. If this has happened then don't panic! Just push the top layer back under the brine with a clean fork or spoon and reseal. You might have to do this multiple times, especially in the early stages of fermentation. We also recommend keeping your ferment somewhere you’ll see it often so you can keep a close eye on it.

Don't double dip

When opening and closing your jar to try it don't be tempted to double dip! This is a sure fire way to introduce unwanted microbes into your ferment and could alter its taste and smell. Although once the ferment is acidic enough it should mean anything harmful wouldn't be able to grab hold and grow there's always a chance, so play on the safe side and just get another fork!

Keep in the fridge once fermented

Once your ferment tastes as you'd like it and you're ready to eat, pop it in the fridge to slow fermentation right down. This will not only help keep your ferment at top quality for longer but if there does happen to be anything malevolent in there (remember this is unlikely if you've added salt and it's acidic enough) then that growth will be slowed down too. While you're eating it make sure to press that top layer back down under the brine to help prevent off flavours and smells and reduce the risk of something growing on the top layer.

Stick to the colour rule of thumb

We’ve also got a handy rule of thumb for dealing with any unwanted growth on that top layer. If you see something coloured or fuzzy (blue, brown and black mould growths are common if exposed to air) then you’re going to want to discard the entire batch because you can’t be sure that the rest of the batch isn’t contaminated. BUT if you see a creamy, white layer then that’s likely some type of yeast (often kahm yeast) which is safe to consume, so you can just scrape off the visible yeast and dig in. And remember to trust your nose and eyes, these are the best tools we have to help us know whether food is safe to eat.

We're always happy to answer questions from fellow fermenters so drop us a line at Or if you want a more in-depth understanding of fermentation check out our fermentation workshops to take a deep dive either with our lovely selves or from the comfort of home!

And for those of you who love the idea of fermenting but just never have the time check out our online shop where we can sort you our fine food-waste-fighting ferments delivered right to your door.

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