Fermented Beets with a Homemade Air Lock System

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fermented red beet slices

photo by vsimon


I am in love.

With my fermenting husband, and these fermented beets.

Vibrant, colorful, crunchy, tangy, salty, probiotic, raw.


Last summer he experimented with sauerkraut, the old-fashioned way. In a ceramic crock, with a rock as a weight. It was beyond gross. Under the rock was blue, green, gray, and white mold. Supposedly, this is to be expected. Nothing wrong a little (or a lot of)  mold, they say. My response? “Yuck, no!”

So I bought some glass crocks with loose fitting glass lids. And tried fermenting diced beets. They were equally disgusting. The brine became as thick as honey and everything turned brown. These were dispatched to the compost bin.

We learned about fancy-dancy German crocks with air locks in the lids. They are lovely, prevent mold and spoilage, but cost three figures. That would make for some expensive veggies.

Then Vince’s engineering nature kicked in. And his frugal streak. I will let him explain from here.


fermenting jar with air lock

air lock lid on a canning jar

photo by vsimon


Simple Raw Fermented Sliced Beets

The recipe is simple enough, but I wanted the fermentation process to be just as simple.

Normally fermented pickles are done in a crock or glass container with a weight on top to keep the contents below the brine level. And then you have mold and scum that needs to be occasionally and regularly removed. This is not a nice task, and rather off-putting for some.

Another common practice is to use a large plastic bag filled with additional brine as a weight and a seal against mold and scum. But it doesn’t always work and can spring a leak.

The method I like best is to use an air lock to keep out the exchange of air during fermentation. Off gassing is allowed by the air lock during fermentation while maintaining an air seal, thus eliminating almost all mold/scum growth.

To begin with, you will need the right equipment. Any size jar will work, just adjust the recipe to fill it. But the jar cap is not typical. I made the air lock cap by purchasing a simple inexpensive air lock from a beer and wine making store. It cost less than $1. Then I fitted it to a standard jar lid by drilling a hole and sealing the air lock into the hole with silicone caulking. I’ve made several of these for different size jar lids, regular and wide-mouth. You will also need a small weight to keep the beets submerged in the brine. We went weight hunting at a local re-sale shop and found small round glass coasters that just fit into my jars. The weight has to be made of materials that are not reactive with the brine. Glass works great. Marble, and the previous rock, started to dissolve in the brine.

Half-sour pickles. What?

My recipe is based on the basic Half-Sour Brine recipe from Joy of Pickling by Linda Ziedrich, with a couple of added ingredients.

Half-sour pickles are not pickles stopped half way through the process. They are pickles that are fermented in lower salt brine.

Classic full sour fermented pickles are fermented in a brine of 5 to 8 percent salt to water ratio by weight. Half-sour pickles are fermented in a 3.5 percent salt brine.

Half-sour pickles also do not take as long to ferment as full sour pickles. These beets will be ready to eat after about 2 weeks in a dark location at room temperature.

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light streaming through paper thin fermented beets

photo by vsimon

Fermented Red Beet Slices


1 quart jar

1 air-lock cap

1 glass weight


fresh beets – thinly sliced. Estimate 6 to 8 medium beets.

1/8 teaspoon ground cloves

1/8 teaspoon ground cinnamon


2 cups water

1 tablespoon pickling salt

Begin by thinly slicing your washed raw red beets. Do not remove the stem end, use it as a handle while shaving off the very thin slices. I use a mandolin to slice the beets, but you could slice the beets with a knife.

Pack the beets into your jar until you are within about 1-1/2 inches from the top. Add the ground cloves and cinnamon. Place your weight onto the sliced beets.

Mix brine in a separate container until the salt is dissolved. Pour the brine mixture over the beet slices until it completely covers all the slices and yet is below 1/2 inch from the top of the jar. Save any unused brine, you will need it later.

Install the air lock cap and fill the air lock half way with additional brine mixture. Set aside in a dark location at room temperature. Place a saucer or plate under the jar to catch any possible spillage as the fermentation process “breathes”. Bubbling should start within days and slow after a couple of weeks. Keep the air lock half filled with brine during the process adding more if needed.

At the end of 2 weeks, remove the weight and replace the air lock with a regular cap. I found the top layer of beets where a bit off color, but where easily removed. Refrigerate and enjoy.


3 kinds of garden beets

fresh beets

photo by lsimon

More notes from Linda:

Use organic veggies. Fermenting cultivates bacteria and yeast that come with your veggies. They will have more if they aren’t sprayed with killing chemicals.

Vince talks about room temperature. That will vary of course. We put our ferments in the basement when our temperatures are over 85 degrees. If your veggies are bubbling vigorously and so much brine has overflowed that the beets appear “dry”, move them to cooler quarters. And add more brine.

We have used this equipment for sauerkraut with caraway, shredded carrots with thyme, cucumber pickles, and hot radishes. The cabbage, carrots, and cukes where as wonderful as the beets. The radishes were musty and nasty. So far, four hits and a miss. We are waiting on green beans and garlic.

What delicious fun!

Are you fermenting yet?

16 thoughts on “Fermented Beets with a Homemade Air Lock System”

  1. “That sounds like a lot of work, but those pictures of the beets are beautiful enough to sell the idea. Making the food look good is half the battle, especially when introducing new foods and new cooking methods. Thanks for posting!”

    Yeah right, that’s a lot of work for sure, but i think that’s worth waiting. Can you give us more ferment recipes? Thanks a lot!

  2. His engineering may have kicked in, but can’t say much for the microbiologist in him. For one thing, your lid is loaded with BPA on the underside which isn’t going to stand up to the high-salt, lactic acid. And the rust on the cover? Not so much. You still don’t have anaerobic. Look at it this way. Would you put food in that jar, tighten that two-part lid, maybe suck the oxygen out with a Food Saver? You’d have oxygen-free, right? Would you put that jar on the shelf and expect it to be good, not invaded by air? Not producing botulism? Didn’t think so. Oh, and love the black grommet. Made from petroleum and not at all food-safe. Yeah, I have the Pickl-It. And it was made to create safe food. Not what you’re doing. That pop-hole-in-cover has been around for half-a-dozen years and it has been proven to NOT WORK. You’re doing a disservice to people.

    1. Tim,
      I understand your concern with the BPA on the lids. I am concerned also, but I have to work with what I have, weighing the pros and cons of each option. I took liberties with the lid as it did not come into direct contact with the contents of the jar (Always leave an inch or so between the contents and the lid, else it will get expelled through the airlock as it ferments). I also wanted to know if this design worked before investing to much time and money into the project. At first I did not have a better option, but I have since updated my design to an all plastic (food grade) one piece lid with a silicone seal. The black rubber grommet may not be food grade (I am looking for one that is.), but it also is never in contact with the contents of the jar. That is a risk I have chosen to take.
      And you are right, I am not a microbiologist. No one removes the oxygen from their fermentation jars. The lid is simply closed and the fermentation process expels the oxygen as it releases carbon dioxide. My lids seal well enough to maintain a low oxygen environment that is needed for the anaerobic lactic-acid bacteria to do their thing, while staving the undesirable oxygen loving aerobic bacteria. I have found it to work very well. I have not been able to prove it doesn’t work.

      Thank you for your concerns.
      As with any internet information, use at your own risk.

  3. Hi, this is the kind of do it yourself lid i am looking to make for myself. Question, there are so many air locks on the market, i have seen in person the air lock on the pickl-it system – they are very high quality. Where did you get your air lock? Any links? Also, did the air lock come with the rubber gasket? And, lastly, that lid is different that the 2 part lids i have – you know the regular mason jar lids. did you get those special or, i could use the regular mason jar lid i suppose. Thank you!! (Very timely post – the harvest is going off!)

  4. That sounds like a lot of work – but those pictures of the beets are beautiful enough to sell the idea. Making the food look good is half the battle – especially when introducing new foods and new cooking methods. Thanks for posting!

  5. Thanks! By the way, did you peel the beets? Can’t wait to try this-I love beets. I’ve been curious about making fermented vegetables and you’ve encouraged me to take action!

      1. Well, I would say $2.59. You really ought to sell this idea to the canning jar manufacturers! 🙂

      2. PMx2,
        That is exactly why I am not marketing the caps. They would cost me $2.50 in materials just to make them. Unless I could sell thousands, then the costs would drop. But I don’t see that happening.

      3. I am selling something like this – a one-piece low profile (food grade) silicone airlock. They go for $8.50 for a set of 1 airlock lid, and 1 storage (unaltered) lid. At this price-point, our business is growing at a healthy rate. I’m providing this information to be helpful, not to sell my product, though I am perfectly happy to do that also. 🙂

        I used plastic, to avoid the rust problem – BPA free plastic.This was our flagship product for more than a year. We have just begun to sell Fido jars with our airlock in them – but they are not nearly as popular as our plastic lids, I’m guessing due to price. Fido jars are far more costly to purchase wholesale, require more time and more costly equipment to process, and they are more expensive to ship.

        If you make lids and sell them, you have to make sure they are food grade. I got stopped on the first incarnation (with the prototype) precisely because I could not find a food grade grommet in the size I needed. The only way I could do it was by ordering them in bulk from India or China (NOT an option as far as I was concerned for many reasons), or make it myself. I settled for making it myself – I cast my own parts from silicone. I understand that brewing shops DO have the right size grommet for the airlocks though – at least some do. You’d have the same issues with silicone – any that you use has to be food grade.

        As for the air-tight issues, disregard anyone who says that the environment has to be “airtight”. It does not. It only needs to be snug enough that air cannot freely circulate. The inside pressure is higher than the outside pressure on the jar, so air only moves one way – out. A reasonable seal around the edge of the jar is sufficient. (The Pickl-it people have a LOT of erroneous information on their website, which has been repeated and further distorted by people who do not understand the behavior of air and water. And just because someone is going to take issue with me saying that, I’ll also state that their information is VERY one sided – they apply all the GOOD sounding science to their side, but not to any of the other options, while applying the BAD sounding science to the other options, but not to their own product, where it applies equally.) If an environment for pickling is airtight, then the gas that you are trying to release CANNOT get out.

        Hope this information is helpful.