A Beginner’s Guide to Fermenting Vegetables

Category: Fermentation, Vegetables

Fermenting might sound like something for hippies or lab coat technicians, but nothing could be further from the truth. If you’ve ever eaten sauerkraut, you’ve already had fermented vegetables. And the good news is: it’s ridiculously easy to do it yourself. This post will guide you through everything you need to know to get started.

WHAT IS VEGETABLE FERMENTATION?

Vegetable fermentation is a form of lactic acid fermentation: sugars in the vegetables are converted into lactic acid by lactic acid bacteria that are naturally present on your vegetables. This lactic acid lowers the pH, inhibits unwanted bacteria, and ensures both preservation and flavor. These bacteria do more than just protect your vegetables from spoiling—they build a whole new flavor palette: fresher, more acidic, more complex. You don’t need to add anything extra: lactic acid bacteria, sugar, and moisture are all already in your vegetables. Take white cabbage: about 90% water, 1–3% sugar, and a colony of bacteria eager to get to work.

Which vegetables can you ferment?

Although sauerkraut is the most famous example of fermented vegetables, you can ferment many more: carrots, bell peppers, beets, chili peppers, cauliflower, sweet potato, parsnip, kohlrabi—they all participate enthusiastically. Hard vegetables usually do better than leafy greens, although exceptions like bok choy are definitely worth a try. The shape doesn’t matter much: slices, cubes, whole vegetables—it’s all possible, as long as you consider the moisture content and fermentation time. For example, a whole beet ferments more slowly than thin slices.

How to Prevent Failure in Vegetable Fermentation: salt and (no) oxygen

Your vegetables are full of all sorts of microorganisms: lactic acid bacteria (good), but also yeasts, molds, and pathogenic bacteria (less good). They compete for the available sugars and oxygen. To give the right bacteria the upper hand, you need to do two things: Add salt and keep oxygen out. Let’s look at each.

1. Adding Salt: Your First Defense

Salt is your first line of defense. With 2% salt (that’s 20 grams per kilo of vegetables), you give lactic acid bacteria a head start. Less than 2% is risky, as it gives yeasts and molds a chance. More salt also inhibits the good bacteria and it becomes very salty. Salt also draws moisture from your vegetables, which is useful for things like white cabbage: it produces enough of its own brine to be fully submerged.

2. Keeping Oxygen Out: The Anaerobic Advantage

Lactic acid bacteria prefer to do their work without oxygen (anaerobically). Most other microbes love oxygen, so you want to cut them off. This can be done in three ways:
a) Fermenting under water: Keep your vegetables completely submerged in their own brine or an added brine. Use a weight to keep everything down.
b) Airlock: A jar with an airlock allows gases to escape but lets no air in. Ideal: you don’t have to “burp” it daily, and molds don’t stand a chance.
c) Vacuum fermentation: Put vegetables and salt in a vacuum bag, seal it, and you’re done. It uses plastic, but your fermentation is safe and tightly controlled.

Rotpot fermentation starterkitkimchi

To ferment is to transform, turning the simple into the complex, the mundane into the magical, with just a little salt and patience. – YT

Safe fermentation tools

Basic Sauerkraut Recipe

Ingredients:

  • 1 kg white cabbage
  • 20 g salt (2%)
  • 5 g mustard seeds
  • 4 g juniper berries
  • 3 g caraway seeds

Equipment:

  • Sharp knife or mandoline
  • Large bowl
  • Sauerkraut crock, canning jar, or vacuum bag
  • Possibly a tamper or clean fists

preparation

1. Finely shred the cabbage. Remove the outer leaves and the hard core.
2. Mix with salt and spices.
3. Knead/abuse until enough liquid is released.
4. Pack into the jar and press down firmly.
5. Ensure the cabbage is completely submerged in brine (use a cabbage leaf and a weight if necessary).
6. Seal with an airlock or other method.
7. Ferment for 1–3 weeks at 18–21 °C (64–70 °F).
8. Taste regularly. Ready? Store it in the refrigerator.
9. Any mold on the surface: just scoop it off.

FREQUENTLY ASKED QUESTIONS ABOUT FERMENTING VEGETABLES

For vegetable fermentation, uniodized sea salt or rock salt is usually used out of tradition and for cosmetic reasons (table salt can make the brine cloudy). However, in principle, you can use any kind of salt you have at home: iodized salt, sea salt, rock salt, or even low-sodium salts. The iodine concentration in table salt is too low to significantly impact the good bacteria.

No, you can start with very basic equipment. A simple canning jar (like a Weck jar) is perfect for beginners. You can also use cheap preserve jars (but be careful of pressure build-up) or vacuum bags. More traditional options include sauerkraut crocks. The most important thing is to stick to the principles of correct salt content and keeping oxygen out.

If you see some mold forming on the very surface of the brine, it’s usually not a cause for panic, especially if it’s just a small amount of white mold (kahm yeast). As long as the vegetables themselves have remained submerged under the brine, they are protected by the anaerobic, acidic environment. Simply scoop off the moldy layer from the surface with a clean spoon. The rest of the ferment should be perfectly safe and delicious.

Fermentation time can vary greatly depending on the vegetable, the size of the pieces, and the ambient temperature. For sauerkraut, a good starting point is 1-3 weeks at room temperature (18–21 °C / 64–70 °F). The best way to know when it’s done is to taste it regularly. Once it reaches a flavor and texture you enjoy, move it to the refrigerator to slow the fermentation process down dramatically.

No, you don’t need a starter culture as the microbes you need are naturally present on the vegetables. However, it can be useful when you:

  • want very consistent results, for example in a restaurant or industry
  • want to ferment cooked vegetables (e.g. fermented ketchups)
  • want to ferment with less salt
  • want to get quick results
  • you prefer not to take any risks with regard to safety
  • you’re currently using sauerkraut juice or whey to start your vegetable fermentation. That is absolutely inferior to a vegetable starter, which introduces a wider range of lactic acid bacteria than, for example, sauerkraut juice.Check out our vegetable starter culture here.

Want to learn more? Take our comprehensive vegetable fermentation course

Safely and creatively

In 30+ bite sized English spoken video lessons you will learn all about making fermented vegetables at home, without the need for special tools.

  • Learn to ferment all vegetables
  • Save money, by never having to buy fermented vegetables again
  • Incite your culinairy creativity
  • Promote your probiotics
  • Many free bonusses: including a FREE bonuscourse: the basics of fermentation.

by Fermentation fundamentals

This course is part of our Fermentation Fundamentals education program.

About the Author (Meneer Wateetons)

Meneer Wateetons is a renowned Dutch foodwriter, teacher, fermentation specialist, sausage maker and the owner of startercultures.eu. He has written 9 books on culinary topics such as fermentation, alcohol making, sausages and charcuterie making and deep frying. He has taught many hobbyists, chefs and food professionals about these topics.

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