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  • Writer's pictureKatherine Young

The Basics of Lacto-Fermented Vegetables

Updated: Sep 25, 2021

What is Lacto-Fermentation

Lacto-fermentation is the process of preserving vegetables with the use of the bacteria lactobacillus. This bacterium is present on all surfaces especially on the surface of the vegetables that you will be fermenting. This is a wild ferment, meaning that all the bacteria required is already present in your environment and nothing cultures will need to be added to the mix. Salty brine is the most important part of lacto-fermentation, as appropriate salinity equals safe fermentation. Lactobacillus can thrive in environments higher in salinity than most bacteria. By creating an anaerobic environment for your ferment, it hinders new bacteria from entering the environment allowing the lactobacillus to thrive. Under the right conditions, these guys are literally protecting your food from the bacteria and fungus that will cause it to rot.

The Science of Lacto-Fermentation

When the proper anaerobic environment is created, lactobacillus will take the carbohydrates from your vegetables and metabolize them into lactic acid. As the lactic acid increases in the jar the overall pH of the brine will increase in acidity. This increase will aid in protecting the food products from rot causing bacteria as most cannot survive in a pH lower than 4.6.

During this metabolic process the lactobacillus excretes CO2. This is what causes the bubbling effect in your ferment. However, a happy ferment will give off a large amount of CO2. If the fermentation vessel does not have a way for the CO2 to escape the jar may explode under pressure. Therefore, it is recommended to use products that are specifically designed for the type of fermentation that you are practicing.

Two of the important factors in the science of lacto-fermented vegetables is oxygen and sunlight. Direct sunlight can kill the lactobacillus in your ferment and can encourage the growth of certain funguses. If you are fermenting in a clear jar, it is best to keep it hidden. I keep my ferments in a cedar chest. Direct light can also accelerate the deterioration process of vegetables. Oxygen will also accelerate the rotting process and will encourage the growth of bad bacteria. Therefore, it is imperative that your ferment stay anaerobic, devoid of oxygen.

Time and Temperature

Time and temperature are two important factors when fermenting vegetables using lacto-fermentation. The ideal temperature for vegetable ferments is between 70-74 degrees Fahrenheit. This temperature will encourage the lactobacillus growth and is not so warm that food can spoil. As temperatures cool, the lactobacillus become less active. Once your ferment has reached the flavor and texture you desire, place it in the refrigerator to slow the fermentation process. If handled correctly, some ferments can last months in the refrigerator.

The time that your ferment will rest at room temperature is dependent upon the food that you are fermenting and your acquired taste for fermented foods. Always refer to the recommendations of your recipe or a trusted fermenting manual for the suggested times. For most vegetables, I taste test the ferment every few days to check the taste and texture. Sauerkraut can be an exception as I generally ignore the jars for their four weeks before I begin to disturb their environment.

Fermentation Tools


There are two types of fermentation crocks that are avaliable in a variety of sizes. Open crocks utilize a weight and a lid that rests loosely on top of your crock to keep out sunlight. The weight is responsible for holding the vegetables underneath the brine safe from oxygen. The loose-fitting lid allows for CO2 to escape. Water-seal crocks have a ridge holding the lid in place. Once applied, the ridge is filled with water to create a seal. When pressure builds from the CO2, the water will allow for bubbles to escape from the crock.

Although many antique fermentation crocks are attractive, they should not be used for fermentation as many manufactures commonly used led in production. If you would like to use an antique crock, please research the manufacture and materials used during the time of production.


Weights are responsible for holding the vegetables underneath the brine during the fermentation process. The most important is to be sure that you are using food grade materials that are non-reactive. Some people use river stones etc. in their ferments but beware of using stones purchased at craft stores. You can also choose to use plates and bowls in larger ferments.

Airlock Lids

Airlock lids come in multiple varieties. However, they all preform the same function. They allow for excess CO2 to escape while keeping oxygen from getting into your ferment. They are inexpensive and effective.


A tamper is an inexpensive tool that is used to press down vegetables that are fermented in their own brine.


Jars are a great fermentation vessel as they come in a multitude of sizes and colors. Purchasing canning jars is a great way to ensure that your glass is food grade and that the jars can easily withstand pressure.

I prefer using mason jars with airlock lids due to the size varieties available. The variety makes it easy for me to make small batch ferments based on the fresh produce I have available in the garden. It is cost effective and allows me to ferment multiple projects at one time.


When cleaning it is important to remember the difference between cleaning, sanitizing, and sterilizing. Cleaning is removing the dirt off of a surface with the use of soapy water. Sanitizing is the process of removing most of the bacteria and fungus from a surface. Sterilizing is the process of killing all bacteria on a surface. The difficulty is finding the proper balance to cultivate positive bacteria growth without over sterilizing the fermentation environment. For the purposes of lacto-fermentation, it is best to use sanitization to ensure that good bacteria is not completely eradicated from the mix.

Sanitization Methods:

  1. Run all materials through a sanitization cycle in the dishwasher.

  2. Submerge all materials in simmering water.

  3. Soak your materials in a diluted bleach solution.

  4. Use a foam rinse sanitizer that is sold for fermentation purposes.


The most important choice in salt is knowing that your salt product does not contain any anticaking agents. These are usually present in iodized salts or table salts that we often keep in the kitchen. My favorite salt to use in fermentation is canning salt because it is fine grain and does not contain anticaking agents. You can also choose to use kosher salt, sea salt, or Himalayan pink salt. Just be sure to read the labels to ensure that it doesn't contain any additives. I recommend using fine grain salt to ensure that the salt is being dissolved or evenly distributed.

The salt in your ferment will also harden the proteins in your product, giving it that crisp and crunchy texture (Shockey & Shockey, 2014).

Vegetables in Saltwater Brine

Almost all vegetables can be fermented in a saltwater brine. The food will be held beneath this brine creating an anaerobic environment for the ferment. Remember that the salinity of your brine needs to have the right balance to allow lactobacillus to thrive while being uninhabitable for harmful bacteria. The brine should always be calculated by weight for safety, which is why we do not recommend following fermenting recipes that use volume measurements.

Be sure to use non-chlorinated water when creating a brine for live fermentation as chlorine can harm the growth of good bacteria. To weigh, place your jar on the scale and zero it out. Add the vegetable, record the weight, and zero the scale out again. Add the water required to cover the vegetables and record the weight. Remove the water from the jar, calculate and weigh salt, mix the brine and pour it over the vegetables (Weissman, 2019).

For vegetables in saltwater brine

Vegetable Weight + Water Weight x 0.02-0.03 = Amount of Salt in Grams

Vegetables in Self Brine

Sauerkraut is the most popular vegetable that is fermented in its own brine. When making a kraut, the vegetable is shredded, salt is applied, and the product is massaged. Salt activates the osmosis process and begins pulling water from the cells of the product. The expulsion of water combined with salt is the brine for your ferment. Self-brining vegetables will require the use of a tamper to pack them into a vessel, remove air bubbles, and ensure that all food content is beneath the brine.

For vegetables in their own brine

6 grams of salt per every pound of prepared vegetable

Tips for Safe Fermentation

  • Do not use reactive materials when fermenting including plastics and metals.

  • Do not wash vegetables with soaps or chemicals before fermenting as it kills beneficial bacteria.

  • Always use recipes that formulate the brine or salt ratio by weight as vegetables do not have standardized sizes.

  • Only use food grade weights or materials to hold food beneath the brine.

  • Remember to keep the outside of the vessel clean during the fermentation process as the products inside may overflow.

  • Botulism cannot grow in an environment with a pH below 4.6. Using a food grade pH test strip is an inexpensive and effective way to ensure the safety of your ferment.

  • Life fermentation works best in temperatures between 70-74 degrees Fahrenheit.

  • When in doubt, throw it out.

Thank you for reading!

And remember...

Good food comes from your own hands.


Shockey, K., & Shockey, C. (2014). Fermented Vegetables: Creative recipes for fermenting 64 vegetables & herbs in Krauts, Kimchis, Brined Pickles, Chutneys, Relishes & Pastes. North Adams: Storey Publishing.

Weissman , J. (2019, March 9). The Guide to Lacto-Fermentation: How To Ferment Nearly Anything. [Video] YouTube.

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