The 3 Biggest Fermenting Mistakes You’re Already Making

biggest fermentation mistakes

If you naturally ferment probiotic rich food at home like sauerkraut, you may or may not be aware of the recent controversy surrounding mason jar ferments. Recently, Lea from Nourishing Treasures did a series of posts in which she tested 18 different sauerkraut fermentation set ups to see which ones were the best — everything from a recycled salsa jar to an expensive Harsch Crock. She tested for the prevalence of lactic-acid producing bacteria, the absence of mold or other undesirable microorganisms, ease of success, and more. Her series was in-depth and fun to read if, like me, you geek out on this sort of stuff. It was also written over the course of more than a month. I invited Lea to write a guest post for you here to summarize her most important findings, and this is what she shared. Thanks, Lea!

Like all the other fermenting “experts” in the blogging world, I am not a scientist. Like them, I don’t have a degree. What you’re about to read comes from my thorough research in writing The Science Behind Sauerkraut Fermentation and my personal experience during my extensive sauerkraut experiment.

After the many comments on my blog posts during the Sauerkraut Survivor series, and the e-mails I received directly, I’ve come up with a list of the three biggest fermenting mistakes people make – and ones you’re probably making right now.

Mistake #1: You refrigerate your ferment 3-10 days after you pack your jar

This is the biggest mistake I see people making — not leaving their ferment on their counter longer before transferring to cold storage. If you want maximum probiotics in your sauerkraut (and I think we all do!), you’ll want to let your ferment go through the three stages of fermentation. This is particularly important if you are trying to heal your gut.

In a temperature of 65 – 72 degrees the first stage bacteria, Leuconostoc mesenteroides, are happiest. This is the average temperature in your home, which works out well. At this temp, the first stage bacteria kick in around day 3 and lasts until day 7.

Refrigeration slows down food spoilage; I think we all know this. In the case of fermenting, you are also slowing down the bacterial action. The LABs (lactic-acid producing bacteria) dislike cold, and they cannot truly thrive in it (read: prolifically reproduce). So, you want to leave your sauerkraut out a minimum of four weeks to give time for your sauerkraut to go through all three bacteria stages.

You can view the difference in the maturity and density of the LABs when you view the photos of the sauerkraut brine on Day 3 and Day 7 and then on Day 28.

Remember, fermentation is a method of preserving food. Leaving it on your counter gives it more time for the LAB activity to increase — which, in turn, lowers pH — and prevents spoilage. As long as your jar can keep out the oxygen, you shouldn’t be worried.

Which leads me to…

Mistake #2: Not using a jar that keeps out the oxygen

Oxygen is the enemy when it comes to ferments. LABs prefer an anaerobic (oxygen-less) environment, and our goal is to keep those little guys happy, right?

Aerobically (with oxygen) the yeasts in your ferment can be oxidized to form acetic acid (vinegar), which is not what we’re making here. Yes, you want some tang, but you can achieve tang without vinegar.

The candida-preventing yeast Saccharomyces cerevisiae has the ability to shift from fermentative to oxidative depending on the level of oxygen available. Keep the oxygen out, and this friendly yeast can help your guts heal.

So how do you know if your jar is keeping out enough oxygen? There are a few red flags that can tell us: browned cabbage, yeasty odor, pink cabbage, slime, and mold (we’ll come back to mold in a bit).


Now you don’t need a fancy jar to achieve a healthy, probiotic-filled sauerkraut. There are many inexpensive set-ups that you can use. In my experience, there are a lot that fit the bill — with jars ranging from recycled salsa jars to Fidos, and all manner of airlock systems from a number of different popular suppliers (check out Sauerkraut Survivor – Final Report for all the details). Here are a few of the generic options that worked well:

  • Mason jar with a layer of olive oil across the top of the ferment
  • Mason jar with a white lid and a baggy liner to help hold fermenting cabbage under the brine
  • Mason jar with a white lid and an airlock installed (you can pick airlocks up for a dollar or three at your local hardware or home brew store)
  • Mason jar with a metal lid and an airlock installed
  • and a salsa jar as long as you install an airlock in it

You may be surprised about the salsa jar. I was blown away when we performed our pressure and vacuum tests and found it to be airtight.

I just want to caution you about airtight jars. Due to the CO2 activity happening in the gaseous stage of your ferment, you must allow for an outlet for those CO2 gasses to escape. You want a jar with a combination of airtight seal with the ability to off-gas.

For example, the CO2 can push out through the olive oil, and yet the oxygen can not penetrate. The jars with airlocks provide a tight seal around the lid, yet the airlock allows for off-gassing. The Fido has a vulcanized rubber gasket, which acts as an airlock, allowing CO2 to be released at a certain pressure, but not allowing oxygen to come in.

So there are several options when it comes to jars, and the prices range from pennies to tens of dollars. The least expensive jars performed just as well as the most expensive ones. I personally experienced no difference, and the test results were virtually the same.

Mistake #3: Scraping away mold and thinking it can’t harm you

I know, I know. It’s “normal” to get mold. It’s “normal” to scrape it away and eat it and not die on the spot.

But is it safe?

Before you remind me that mold on cheese is safe, let me remind you that moldy cheese is created in purpose. Certain cheeses, such as gorgonzola or blue cheese, have been cultured to create a safe mold. Moldy cheddar cheese isn’t even acceptable, and certainly mold is unacceptable in your ferment.

Mold can make you sick, very sick. Some people show symptoms right away; others end up with mold sensitivities or other gut issues that evolve over time. It’s just not a risk I am willing to take.

If you’re saying, “But, Lea, I am not eating it, I am scraping it off!” I have to respond with this: mold has roots. Far before you can see the mold on the top of your kraut, the spoilage has begun. I have experienced this myself — spoilage in the brine samples before I saw them with my eyes. In fact, Jar #3, Water Baggy, had just a couple of decaying cabbage pieces on the top of the jar, trapped between the baggy and the glass. At the end of my sauerkraut experiment I removed the baggy and the decaying cabbage (which just had a little bit of white fuzz) and I took a sample of the brine from the very bottom of the 1/2 gallon jar. Guess what? There was mold. Now visually, it looked great. The cabbage was beautiful-looking, and even smelled fine. So my point is, once you get to the point of seeing mold with your eyes, it’s already too late.

Need an Easy Guide to Get Started?

I’ve created a nifty, print-friendly, easy-to-follow collection of 7 naturally probiotic recipes your kids (and you!) will love.


Where to Buy Fermentation Airlocks & Vessels

If you want to find wide mouth jars with airlocks already installed for fermentation, fermentation airlock lids you can use to top your own wide mouth mason jars, and fermentation crocks, check out the listings here.

Lea Harris is a mom and certified health coach who is passionate about her family’s health and well-being. Founding Nourishing Treasures in 2006, Lea encourages others to take baby steps in the direction of health, providing natural alternative information that promotes health and prevents disease by using traditional foods and nature’s medicine. Lea can be reached on her website, her facebook page, on twitter, and via e-mail. Sign up for her FREE video course, Sauerkraut 101.

(top photo by chiotsrun)


  1. Ruth says

    If the sauerkraut has been refrigerated for about a week can you bring it back out and put on the counter to further ferment.

    Thank You

    • says

      I have not tested this out to prove one way or the other, but I don’t believe it would be the same. The LABs would have been subjected to temps below where they are comfortable, and I am unsure they would bounce back after a week in such conditions.

      • tjsparkes says

        Actually, I think Ruth is correct. I use the juice from a previous batch to fuel up the probiotics in my next batch. The juice has been refrigerated between batches. Unless you’re freezing, the cool refrigerator shouldn’t kill the probiotics. Lots of live probiotics are sold in the refrigerator section of the store.

    • Janet Jenson says

      I love the glass weights. I like them so much I bought 4 more sets. I use them with the white lids with airlocks. I keep the jars out on the counter where in the summer when my in-home temperature ranges from 75 to 85 F so after 3 days I do put the whole jar in the fridge with the glass weight/s and the air lock still intact. It still improves with age in the refrigerator and I like it cold when eating it. I use the liquid from one batch to start the next one. BTW I put vodka (because it is a disinfectant) in the airlock instead of water.

  2. says

    Judy Chin — I actually prefer coconut oil for sauerkraut. That way, I can refrigerate my final product and the coconut oil layer solidifies. Then, I just pop it off. Easy peasy. I can even melt it and use it in something else later. It’s kinda hard to get rid of the olive oil layer, unless you just want to stir it in to the final product.

        • Eimearrose says

          The good bacteria aren’t fungi so coconut oil won’t kill them. The good bacteria are already in the kraut in small amounts before fermentation, which lets them grow. Oil prevents anything else entering (like fungi or unwanted bacteria).

    • says

      What have you learned when reseaching the risk of botulism with the oil on ferments that makes you think this is a safe practice? Evernthing I have read says that oil plus any humidity is a very dangerous combination. This is why you only use dried herbs when making flavored oils or use them up quickly.

      • KristenM says

        I’m not worried about botulism because the ferment is acidic. So, I’m no more worried about leaving my oil out on top of an acidic ferment than I am about leaving my oil out on my counter or in my room temperature cabinet (something I have always done). Plus, preserving food by leaving oil or fat on top of an acidic brine is a traditional practice that goes back hundreds, if not thousands of years. We’ve pickled pork and cured other meats by putting them in salt brine and topping it with tallow. We’ve cured olives for thousands of years by putting olives in a brine with lemons and topping with a layer of olive oil. Just about every culture around the world has examples of these traditionally fermented foods in acidic brine topped off with oil or fat.

        If botulism were a real risk, people would have stopped fermenting this way. Or, in the very least, we’d have heard about documented safety precautions people took to prevent it (the way we’ve heard about how to prevent botulism when canning).

        • says

          The ferment becomes acidic but it doesn’t start out acidic. I have heard that you shoudn’t ever keep oils that you flavor with fresh herbs for the same reason. While the risk is low (there really aren’t many cases of botulism) it is a real risk. Just because my family survived riding without car seats doesn’t mean that car seats aren’t safer than no car seats.
          There isn’t a risk of botulism in oil. The risk is that the botulism spores will be introduced by the plant food and then make their way into the oil where the acid is low and never gets high. Well made oil will not have botulism spores in it so of course it isn’t a risk leaving it on the counter. It is the combination of low acid food (the start of the fermenting process) and an oil that can protect the spores from the rising acid levels that makes it risky.

          • KristenM says

            Yes, but it starts out salty! And salt prevents botulism from taking hold just as well as an acidic environment.

            • KristenM says

              Put simply, the things that work against botulism are:


              The presence of any ONE of these factors will make it impossible for botulism to reproduce in enough numbers to make you sick.

              So, for the first few days, while you’re waiting for the ferment to become active and acidic, the salty brine is keeping you safe. After that, you’ve got an acidic brine, and you’ve got TWO of these anti-botulism agents going for you.

              • says

                How much salt does it take to prevent botulism? Obviously there is a unsafe level or there wouldn’t be the advice about making sure your tomato sauce is acidic enough when canning it to prevent botulism. Tomato products usually also have added salt so how much is needed to prevent botulism and how would one know if there was enough in their ferment?

                • says

                  Patty: According to modern food science, it takes 10% salt to be safe in preventing botulism, which is higher than most people want to eat out of hand. Acidity should be about 4.5 or lower to prevent botulism. Botulism takes time to develop, so starting out with a much lighter brine and waiting a few days for fermentation to commence is not cause for concern. Cause for concern is foods that are below 10% salt or above 4.5 ph stored for a period of time. It is only necessary to meet one of these two parameters for the prevention of botulism. many foods that we store in the fridge meet the potential botulinum supporting criteria, but they are not stored for a very long time. i see people making mistakes with olives all the time thinking that they can lye cure them and then store in a light brine for months or even years.

              • Andre says

                I am speaking of 32 years experience and probably thousands of batches of fermented vegetables, I have never used salt in my ferments, my whole family eats the krauts and I have given away many jars of it, we never had a problem with harmful bacteria,I have had the krauts in the fridge for more than 6 months and it is still good.

                • Andrew says

                  Hey Andre, I am curious as to how you ferment vegetables without salt. I have a few family members who need to restrict sodium in their diets, so this is of interest to me.

      • says

        I replied to this below, but the only thing I’d think twice about would be garlic, due to the botulism spores naturally found on garlic.

        But ferments? I’m not worried about it. There is sinmply no evidence showing it to be harmful.

          • says

            There isn’t one. There are no studies showing a risk of botulism in oil-topped ferments.

            That is why I’m not worried :)

            However, if you can back up your concerns with a scientific study proving oil-topped ferments to be harmful, I would like to read it and would be willing to change my opinion at that time, based on any evidence.

            • says

              You haven’t found a single study done on the safety or lack there of with oil topped ferments and therefore you think that proves that they are safe? So the best way to know that something is safe is to check and see if anyone has studied it yet and as long as they haven’t it must be perfectly safe.

              • says

                Why are you afraid of using olive oil? Did you read a study where it was shown to be unsafe? If so, then I can understand your fear.

                Otherwise, it is a food that we’ve been eating for thousands of years and that is proof enough for me that it is safe. I don’t need a study to prove olive oil is safe :)

                • says

                  No one said eating olive oil was unsafe. Mixing oil with a moist food however is dangerous and can be contaminated with botulism spores and be deadly, especially if you keep it in storage for a long time. A small amount of oil is not the problem however a large volume of oil all together (like topping a ferment) is the issue.

                • Gretchen says

                  I’m curious why no one has addressed the fact that olive oil will go rancid quickly when exposed to oxygen (which is right above it) if used this way in a ferment. (Source: The Whole Foods Encyclopedia by Rebecca Wood)

    • Jassica says

      At what temperature do you ferment? Coconut oil is solid below 76 degrees (I believe). How does this allow for off-gassing? Other than that, it’s brilliant. Also, olive oil will thicken significantly when refrigerated and shouldn’t be terribly hard to remove most of it.

  3. Jeff says

    Thank you for this helpful information.

    Regarding Mistake #1. Does it depend on what I am fermenting? How long should I leave my pickles and other vegetable ferments out?

    • KristenM says

      Yes, the ideal length depends on what you’re fermenting. Therapeutic veggie ferments traditional for long-term storage (like sauerkraut, Kim chi, cortido) should be fermented a long time to maximize LABs. But a simple condiment like ketchup doesn’t require that kind of time because the goal is less therapeutic and more about achieving the right flavor.

  4. Kelly Alpacapeople via Facebook says

    Sauerkraut is one thing I’ve never attempted because of mold. I’ve had people tell me “it’s safe,” “it’s just the bloom,” etc. But, I have developed a severe mold allergy to the point where I can’t eat peanuts, corn, pistachio’s etc. I was wondering about air-locks and kefir…are they necessary?

  5. says

    Re: the layer of olive oil. I’m going to start a fermented peach chutney in a mason jar (actually a Ball jar) tonight, and I’m a bit apprehensive about leaving it out on the counter for that long. I don’t want to use my very expensive EVOO (I’ve stopped buying cheaper olive oils) as a seal because, hey, it’s expensive. Would melting some coconut oil (still expensive, but cheaper than the EVOO) and pouring it on top work? I also think the flavor would compliment the chutney better.

        • KristenM says

          Yes. If you’re striving for a sweet ferment, you don’t want to ferment it for a month! A few day will give you the flavor you’re looking for.

      • Ken B says

        Doesn’t seem like it would work too well when the coconut oil re-solidifies. Expanding gas/brine would just push the solid oil up and out of the way (possibly at an angle).

        • KristenM says

          Since I live in Texas, that’s never been a problem for me. My coconut oil is usually always liquid unless I’m intentionally chilling it!

    • Dean says

      The airlocks only cost about 75 cents or so, rubber stoppers are inexpensive too.
      You can use either a Ball Plastic Reusable lid and drill a 5/8″ hole in it or the more expensive Tattler brand reusable canning lids with the same size hole. You’ll need to use a metal canning ring to hold the Tattler down.
      I stick primarily with wide mouth jars because I have big hands but the same principles work with regular size jars.
      If you want One Gallon glass jars and matching lids try this outlet. These don’t have standard sized canning jar opening so you have to buy their lids but the cost is very reasonable.
      Buy extra plastic lids so you can alter them for airlocks and have enough unaltered lids for closing up the jars for refrigeration. :-)>

  6. Daja Abdelaziz Gombojav via Facebook says

    This seems to go against Sandor’s recommendations in Wild Fermentation. He just covers with a towel, as long as the brine covers all the cabbage. And if it gets mold he just removes it. That is sort of a traditional practice, is it not? Now I feel so confused! LOL!

      • Bekah Rieke says

        I make sauerkraut in an open crock covered with a towel. I basically follow Sandor’s method. The kraut is submerged in about 2 inches of brine and weighed down with a plate that just about covers the open surface area of the crock. Once at the end of October, I had a thick layer of mold develop at the top of the brine. After about a month, I peeled it off using tongs (it came off like a piece of plastic) and assumed the kraut was ruined. Upon further inspection it seemed fine so I tasted it. It was great and I ate the whole crock throughout the Winter not experiencing any signs of sickness. I think that the mold almost acted like a seal and that the kraut submerged in the brine was definitely not getting any oxygen. It’s actually the best batch I’ve ever made.

        • John says

          I think that as always people are over reacting. I grew up making Sauerkraut since I was a small child. We always had several crocks going in the basement with nothing on top of it then several layers of old pillow cases. Mold? So what, we took it off and that was that. None of our extended family ever died or got sick because mold none got sick of other illnesses modern people obsess about.It is this over protectiveness and concern that is the biggest problem these days. People are growing up weak, their bodies can’t handle real food anymore and children get sick just looking at nature.

          Make sure you have 2-4 inches of brine over top of your produce and make sure you let it ferment 10-12+ weeks minimum…4-5 weeks at 65-75degF and the rest of time in a cool dark spot to permit the bacteria to finish the job. make sure the temp does not go below about 50F and not higher than 60F during the second phase. I have started to use 20gal fermenting cocks with water locks for sauerkraut (wonderful stoneware directly from Poland), but frankly, I never have seen any difference in taste. I always have several 10-20 gal fermenting cocks going with the products of my garden.

  7. Tziporah Falowitz Hirsh via Facebook says

    I have been making kimchi for years but never left it out at all. Have I been getting ANY probiotic benefits???

  8. Erin says

    Thanks for posting this!
    So just to clarify- If I am starting some ferments in wide mouth mason jars with the standard cap (the kind that are normally used for hot water bath canning), should I throw some coconut oil on top and still screw the lid on? What about other ferments- is it a good idea to drop some oil on all of them? Slightly dumb questions, I know, but I like to be specific when it comes to whether or not I am eating mold :)
    Thanks and God bless!

    • KristenM says

      If you use oil on top, you don’t need the lid unless you want it. Just cover with a towel to keep flies and other bugs out.

    • says

      The oil will act as a barrier between your ferment and the air – no need to cap unless you want to keep the dust off it. If you do cap, use a white lid – the metal lid and ring keep out the air so well that it also hold in the pressure (and could “pop” in your face when you go to open it).

  9. says

    I ordered airlocks from Amazon from a company called Pickle-Pro. They are very reasonably priced and fit onto a standard wide mouth jar. Finding wide mouth jars can be hard, so I ordered some of those from Amazon too.

  10. Lara says

    I’m with Daja — I thought that a crock pot with brine covering the cabbage was okay. Tamp it down with a plate and use a jar filled with water for weight and then a loose towel covering for bugs. If this is not okay, should I transfer my week-old mixture now to Mason Jars and do the coconut oil cover? So confused!

    • KristenM says

      Lara, something can be okay without being optimal. I think what you choose to do should depend on your goals. If you want to create the most therapeutic, LAB-rich ferment, you would do better in an airtight system that would produce less acetic acid (vinegar produced when yeasts interact with oxygen) and more lactic acid. If you’re just going for flavor, enjoyment, and a decent amount of probiotics, then an open air ferment may be all you need. The only problem I see with open air ferments is that they are more likely to mold or produce inconsistent batches. Thoughtful, well-researched, and well-meaning people can all reasonably argue about how mold may or may not be “safe,” but we can all agree it’s less than ideal.

  11. says

    I’m not sure you have convinced me about scraping off the top mold. You didn’t cite or prove anything about the type of mold or the harmfulness thereof, just your “eww! there’s mold!” stance. Any evidence? We’re talking about traditional preparation here, so I’ll go with the traditional non-airtight crock method over your “ew” unless there is some other factor I’m missing. And you are contradicting the whole idea of the mold being aerobic-loving whereas the brine is anaerobic. That makes sense to me. Any rejoinders? I’m open.

      • says

        Really? Your sources are a couple of 150 word blurbs on LOL. No studies were cited and no evidence was given, only statements. If this is how you conduct your research I’m afraid I cannot put weight in your testimony (although I do believe you that mold risk, such as it is, can be minimized through use of a proper air lock). I thank you for bringing the question to my attention, but it is still unanswered in my book. I’ll have to conduct my own research and see what I find from actual sources.

        • dianna says

          Settle down Sarah and be respectful. This is not your site. You can get your own if it means that much to you :)

          • GR says

            OK, the answer was a bit rude, but if you’re going to give people health(?) advice I would think that you would want to use a source a bit more authoritative than ehow.

            Also, though I can’t remember the name of the book, I remember when I was in grade school reading the story of a German(?) child who was suffering with a fever. The story described how the child’s mother went to a large barrel filled with sauerkraut, scraped the mold off of the top, and dipped a bowlful of the cool, fresh kraut from underneath. I understand that we should probably avoid certain materials, practice good hygiene, etc., when fermenting, but what were the conditions like centuries ago when people were fermenting food?

  12. Bethany says

    Thank you SO, SO, SO, SO, much for this post, totally cleared some things up for me without hours of research. I am going to do the route of the fido, best price and I can find them locally. Thanks again, this was an awesome series of posts.


  13. Ken B says

    Do you think the pressure in the sealed jars (non-airlock lids) contributed to the good LAB quantities, etc.? I.e. does fermenting under pressure provide better results?

    • says

      This is a super excellent question and one I am currently working on finding an answer to. I do personally feel that yes, fermenting under pressure could indeed provide better results.

      Don’t tell anyone (shhh) but I am currently working on a experiment right now that I just haven’t had the time to share on my blog yet. I have two Fido’s with kraut: one with brine covering the cabbage (with food-grade dehydrator screen), the other with no weight so the cabbage is sticking up out of the brine. It’s been almost two weeks and there are no signs of spoilage at all…

  14. says

    Daja Abdelaziz Gombojav — If you read my post on mason jar ferments, I’ve got a whole big letter written by Sandor explaining the different ways he ferments. In short, he does it all! He doesn’t “recommend” one way or another, but is, in fact, rather of the mind that we should all have fun and do whatever works for us.

    Yes, open air fermentation is traditional. But, scientifically, you should know that it produces different probiotic results than a traditional airtight system (like a ferment “sealed” with fat or oil). Yeast with exposure to oxygen produce acetic acid (vinegar) instead of lactic acid. In an open air ferment, this means your end result is a mix with some acetic acid (usually at the surface of the ferment) and some lactic acid (usually deeper in the ferment, away from the oxygen). That’s perfectly okay and safe. But, it isn’t optimal for those using ferments for therapeutic purposes. Those people want the most LABs possible, and so will opt for an airtight system.

    Plus, simple anecdotal evidence suggests that you get more consistent results the more variables you control, so an airtight system produces more consistent, successful results.

  15. says

    Thank you for putting the word out on the mold! It’s something I never really got my head around because it’s so widely spread that you would be able to eat it safely, but the way you put it definately took care of that!

    The same with home made baby bum wipes with water, oil and a bit of soap. Works perfectly, but why oh why won’t people understand you shouldn’t let it stay on hot summer day temperature for more than a day? It’ll get moldy much faster than your eye will detect.

    Entirely different subject but it reminded me 😉


  16. Joy says

    I ferment vegetable medleys – consisting of kale, cabbage, onions, green beans, carrots, brussel sprouts, celery, etc. Would the same apply to them, ie I need to ferment them up to 28 days? I love the taste of these much better than just plain cabbage.
    Also, if you bake sauerkraut, does the heat destroy all the probiotics?
    Thanks for a good post —- will be changing my methods based on your reply.

  17. Charissa says

    I made my first batch of sauerkraut a few months ago and made mistake #1. I think it was out for about 5 or 6 days and then off to the fridge. No mold. Used a Ball jar with metal screw top. Didn’t get much liquid from the cabbage so added some spring water and then sealed it with some whole cabbage leaves wadded up at the top. After a few days I opened the tops to release some built up oxygen/gases. The kraut was delish but very “young” tasting. After being in the fridge for weeks since it has mellowed and is “softer.” So my question is could you use the Ball jars with the lids I used and every few days just open the tops to release the pressure? Or is it that every time you open the jar you invite the opportunity for mold growth no matter how quickly after you reseal the jar?

    • says

      It could taste “young” if you didn’t add salt to the water (brine). You do want a 2-3% ratio of salt to brine (3 TBSP salt to 1 quart).

      It’s difficult to say if you could use the Ball lids. In theory, it would work, if you knew how much pressure was built up so that you could release it quickly and re-tighten before oxygen was able to come back in. When the CO2 is whooshing out, the oxygen can’t get in.

      It is very inexpensive to purchase grommets and airlocks and convert the lids you have. I have found the grommets on ebay (you want the 3/8″ inside diameter ones) and the airlocks I’ve found for under a dollar.

      • John says

        Brine is better mixed by weight as different salt used has different weights and grain sizes. Larger grain sizes will result in to light a brine and finer grain sizes will result in to high a brine solution. The best way to measure it is to buy a cheap digital scale that has a 1 gram resolution…unless you want to make large batches and then a normal scale is good enough.
        Normally there is really no need to add brine.
        Cut your produce, put it into a glass bowl, stainless bowl or like I do a bowl made from white oak or cedar. Ccrush your vegetables using a rolling pin, or a clean bottle (make sure it is one with thick glass). Pound the crap out of it, mix the in the salt and let it stand for 12-18 hours covered with nothing but a cloth. This will permit the produce to wilt and release the water to create brine. Add your spices transfer to the fermenting container and cover with the brine…chances are you have more brine then you need.
        To ferment items that you don’t want to crush.
        Buy a head or two of Bock Choy , shred it, crush it in a bowl and pound it for at least 5-10 min, mix with ~2 table spoon worth of salt (not too critical). Let stand covered with a towel at room temperature for 12-24 hours transfer the brine into a sterile glass …don’t forget to press out the cabbage. Eat or toss the cabbage whatever you desire (I use it to make kimchee). Bock choy cabbage juice is neutral in taste, has lots of minerals and vitamins and is the perfect starter for ferments like pickles and other.I hate the thought of using plain water, even filtered water to make a brine.

  18. Shannon says

    So you tested the air locks on the bullet point list above? And you received similar results? I’m just clarifying because another blogger (who shall go unnamed) states quite adamantly that only the glass top jars are truly air-tight. Just wanted clarification. Thanks!

    • says

      Yes, I have heard that myth – and I repeat it is a myth. Anyone with a vacuum pressure gauge or air compressor can perform this test themselves to see – don’t take my word for it! :)

      The glass top jars (Fido, for example) do allow for off-gassing since the white gasket acts as an airlock. No, it doesn’t allow oxygen in, but it does allow for CO2 to be released.

      On the other hand, the simple metal lid and ring are just plain tight. I personally wouldn’t feel comfortable using it without an airlock since the seal is so tight and could pop off and hurt you when you go to unscrew it. Even the salsa jar held lots of pressure (that one surprised me!).

      • says

        “On the other hand, the simple metal lid and ring are just plain tight”

        This notion is incorrect. I’ve posted a detailed reply aobut using just rings and seals on Lea’s sauerkraut survivor blog post page. I’ve used mason jar seals and rings, or preferably the plastic mason jar lids with a seal underneath, for years and it work’s fine. Pressure or air leakage have been a non-issue in literally hundred’s of jars of fermented vegetables. The Fido jars work on exactly the same prinicipal, but they are more expensive and the salty and acidic brine can affect the metal bails over time. Also, the lid cannot pop off without loosening the ring and the ring cannot be loosened fast enough to cause a flying lid before the pressure is released out the side of the jar. It can however spew liquid all over the place if the pressure is too high or if the lid is screwed on very, very tightly or opened during the most active part of fermentation. I would not open the jars frequently during fermentation and it is best to top them up before resealing if you do, just to purge air from the jar.

        • says

          I have actually had a lid and ring both pop off when making sourdough for the first time years ago. I had no idea the CO2 that would build up! I have no idea how they both managed to pop off all by themselves, but the glass was unshattered. Quite a shock – and what a mess!

          So the lid can definitely pop off without even touching it.

          I have also had friends of mine relate when they go to release pressure the lids pop off. The metal bands bend due to pressure.

          So from my own personal experience and observations I would not recommend fermenting with a metal lid and ring unless you have an airlock installed to allow the CO2 to release.

          The myth circulating that “threaded lids just don’t hold” is a fallacy. All of us who have experienced what I described above knows this. The hold pressure to a fault.

  19. Michelle Doyle via Facebook says

    You can pick up gaskets & airlocks at any local home-brewing shop for a couple of bucks. Drill a 1/2 inch hole in a standard canning jar metal lid, insert the gasket, pop in the airlock and you are all set. There are several DIY tutorials if you do a quick google search.

  20. says

    Thanks for doing all this and giving us fermentistas the courage to take it further and get the most out of our ferments. Although I did invest in a few pickl-it jars after many failed mason jars of kraut, I am happy to supplement those with some plain fido jars so I can have more batches going concurrently. The pickl-it jars have yielded some fantastic Kraut tasty and still with a little crunch. I only left them out for 12 days so I can’t wait to try 28!

  21. Betsy says

    I’m making kraut in Pickl-It jars in the fridge because my house is cooled no lower than 76 in this summer heat and during the day it’s at 80+. I think I got that idea off their site. I figure it will take a looonnng time to ferment. Any other ideas for hot climates?

  22. says

    Do you have any tips for non cabbage ferments? Or will we need to get the “good probiotics” from cabbage ferments, and use the others for taste?

    I made a tomatillo salsa that is fermenting now :)

  23. says

    Lydia Joy Shatney — I don’t think that’s a real risk at all, so long as your ferment is a)salty enough while waiting for fermentation to take hold, and b)active enough to produce an acidic ferment. You don’t worry about the oil you store in your cabinet containing botulism, do you? So, why would you worry about the oil you store on top of an acidic brine? Plus, we’ve been curing olives for thousands of years by placing them in a brine topped with olive oil. If this were a real danger, wouldn’t we have heard about it by now? Wouldn’t the olive producers of the world be warning us to watch out for botulism and cure our olives a safer way? The brine and fermentation keeps botulism at bay. And, it’s not just olives and olive oil. We’ve been curing lemons this way, “pickling” veggies this way, and even pickling meats (particularly pork, but also other meats) by keeping them stored for months in a fermented salt brine topped with tallow. Botulism’s only a risk in a non-acidic, non-salty environment. With a ferment, you’ve got both those things going for you.

  24. Lydia Joy Shatney via Facebook says

    Kristen – the oil I store in my cabinet is a completely different issue altogether, that’s a rather silly argument. Please just investigate the botulism issue in oil curing before you dismiss what I am saying – I am sure you would not want to lead anyone to consuming a food that has the potential for botulism even if the risk is low, botulism is no joke, people can die from it. I think suggesting that people have been curing things in brine with oil is not enough of an answer – we don’t know exactly how they did it and we don’t know if people got sick from it. Just because something was done in history does not mean it’s a perfectly viable option for us today – we can certainly learn from history, but I’m not convinced we can try to replicate everything the way we think it was done in history. I’m assuming what you are quoting is from Sandor because when I went to look up some actual sources other than him (since that is all you seem to be quoting and sourcing) I saw a source from him that quoted exactly what you said here -problem is, and I have nothing against Sandor, he is not versed in the science of fermentation, though he is quite artistic about it. Let’s see some real sources with actual science, because what we are really trying to do with fermentation is get people healthy and if there are real risks people should be informed.
    First – salty brine won’t change the fact that the oil does not change during fermentation, only the vegetables do – the vegetables may become acidic enough to avoid botulism, but that doesn’t mean the oil will. Botulism spores can be on the vegetables themselves which then comes in contact with the oil prior to the completion of the ferment, so there could be spores in the oil at the end of your ferment and then you’d have to be super careful to get all the oil residue out and possibly any veggies that were touching the oil, thereby losing a bit of your ferment. spores can also be harbored in drops of water surrounded by oil and food scientists have shown that the spores can migrate up to the oil to escape when the pH starts to drop.
    As far as I know and have read there are loads of warnings about preserving foods in oil – they have to be heated once they are done for storage purposes, otherwise they can harbor botulism.
    Here is a good post with more info and sources to read on this very issue.

  25. says

    @Lydia — I don’t see the difference between storing the oil in my cabinet and storing it in proximity to a salty brine. First, let’s clarify something: the oil is not doing the preserving! For the first three days or so, the salt is. Botulism can’t reproduce in salt (this is one reason, among many, why we salt-cure meats that we subsequently smoke like bacon, sausage, etc.). After the first three days, the acid content of the ferment is doing the preserving. Botulism can’t reproduce in an acidic environment. Botulism doesn’t like: cold, dry, salt, or acid. So, if you’ve got oil sitting on top of a salty brine (which later evolves into a salty, acidic brine), where is the room for botulism to take hold? The oil is NOT sitting on top of veggies, or even coming in contact with veggies. So, I don’t understand the hullabaloo. Also, we really *do* know how olives were traditionally preserved — in a salty brine topped with olive oil. We really *do* know how pickling pork was traditionally done — in a salty brine topped with tallow. It’s not just one man, Sandor Katz, reporting on this. It’s history. It’s tradition. It’s like saying that we don’t really know that the Nicene Creed we recite in churches today is the same one that was written back in the fourth century. We know it is. It’s history! It’s tradition! It’s been passed down to us, recorded over and over, in many languages, for more than a thousand years. Why insist on a study when we’ve a)got the weight of history, and b)have the weight of modern science to demonstrate that botulism can’t readily reproduce in the cold, or when it’s dry, or where there’s salt, or when it’s acidic? We already know these things. The conclusion is common sense. Plus, you’re asking for a study to prove the negative, to prove an absence of something. How many samples of oil-topped brine would you need to test before you felt safe? A hundred? A hundred thousand? And what makes those any more relevant than the hundreds of thousands of people the world over who’ve preserved their olives, lemons, veggies, and even meats in oil-topped brines for millennia?

    • says

      I agree. If you feel oil is unsafe, don’t use it. If you want to warn other people not to use it, coming with some scientific proof would help your argument. I don’t think anyone here needs to prove it’s safe today when it has been proven through history. However, if you could prove it is unsafe with scientific evidence, I would be open to removing “oil-topped brine” from the list of recommended set-ups.

      But for now, it is recommended because it does keep the oxygen out – which was the purpose of my study: to determine which methods keep out the oxygen. There are plenty of jars left on the list that do a great job at keeping oxygen out – and I honestly don’t think the oil-topped brine would be the preferred choice anyways.

    • says

      Botulism aside, oil is a primitive means of sealing food against oxygen, which most people probably have little use for. Oil and water do not mix well. Putting even a drop of oil into your oil bottle can rapidly accelerate oxidation causing the oil to become rancid in short order. Just because people did it anyway, doesn’t mean it is a great idea. People do lots of things out of necessity. I’m sure there is a place for oil in preserving, but I think for the most part it is a moot point and that there are much better options. It is also expensive unless cheap oil is used and cheap oil is usually bad for our bodies.

  26. Sarah says

    Just wondering about rule #1. When using a starter such as caldwell’s or body ecology do you still need to ferment for longer than 10 days. The instructions that cone with these starters say to ferment for just 10 days and then transfer to fridge…..
    Thanks for all your hard work you’ve put into this research:)

      • Dean says

        Along this line of thought do you believe or possibly know with some degree of certainty that having a root cellar was a major portion to the equation of lacto-fermentation and long term storage?

        I have my own thoughts but truly would like to hear yours.

      • violet says

        MY fermented vegies are at day 5. I too am using body ecology vegtable starter,in a glass gallon jar with lid. The second and third day it built up pressure and I burped it, thereafter it seems to have quit working. The brine is clear. This recipe, (from Dr Mercola website) has no salt in it. Do you think it is okay, and just needs more time. Body Ecology recipe says 3-7 days. I’ve made saurkraut successfully for years, but always with salt. I’m a little perplexed. Thank You

  27. Caitlin says

    I was wondering how this applies to culturing yogurt or condiments like ketchup and mustard, or sourdough bread? Do all cultures need anaerobic environments, or just the vegetable ferments? Can I still make yogurt in my yogurt maker even though it isn’t air tight?

  28. Beth says

    Was there previously a list of airlock lids and other options that is not appearing in the article now? I could have sworn there was, but now I can’t find it.

    Also, I think the link at the end of the article is not pointing to the intended location. When I clicked on the link in this sentence, there were no fermenting jars or airlocks listed, just various other kitchen gadgets like grain mills, etc.:
    “If you want to find wide mouth jars with airlocks already installed for fermentation, fermentation airlock lids you can use to top your own wide mouth mason jars, and fermentation crocks, check out the listings here.”

  29. JohnnyD says

    Lea H,

    First off I wanted to thank you for literally looking under the scope in the name of safety and better ferments. I hope you continue to dive deep. I’m starting a Fido jar collection now.

    Some comments.

    1. I want to believe oil on top of the brine is an effective and safe barrier on the surface, however as raised before there could be a risk of botulism spores being harbored in little gaps inside the oil barrier itself. All it takes is a spec of vegetable matter being surrounded by the oil for the conditions to be right. You challenged a previous poster to show a study that proves this to be a risk. There may not be peer reviewed studies conducted on ferments and oil barriers but there is plenty science when it concerns preserving foods in oil. For instance sun-dried tomatoes in oil. Or oil infused with fresh herbs. Here’s an example warning:

    2. On the open crock mold issue. My family has been making sauerkraut for 2 generations in an open crock. My great-grandfather used to make it by the 55 gallon drum full. It has always been accepted practice that mold will form on the top of the brine, and you remove it. End of story. I want to challenge your arguments with two points:
    A. You claim that molds are only acceptable on foods such as cheeses. Doesn’t the mold that grow on cheeses also have roots that penetrate all throughout the cheese? Isn’t it common practice if you have a hard cheese that starts growing mold on the surface, to just scrape or cut off the mold and continue to eat it? What about the roots?
    B. You claim that you have found mold throughout the jar brine when it starts growing on the surface. Are you able to identify this mold? If you can identify the mold growing in the brine as a harmful mold I’d be more cautious but just because you see mold under a scope doesn’t 100% mean it’s harmful.

    I’m also a little confused about molds. I thought molds were aerobic, which is why they only grow on the surface? Are the roots of molds able to survive in anaerobic conditions? Or are they growing in the dissolved oxygen that exists in the brine? Lastly lets some invisible to the eye molds do start growing as the ferment process goes on. 5 weeks later when your ferment is done and acidified, wouldn’t the amount of lactic acid kill the molds and whatever biological threat in the brine? However these dead, allergenic, or dangerous organisms would be dead in the brine, BUT still showing up under the microscope correct? So is there a threat from ingesting dead mold organisms? Or is the threat from alive mold organisms?

    Maybe mold is only dangerous when it is left on the surface for extended periods of time, which would prevent the drop of the pH, and prevent the lactic acid bacteria from preserving and destroying any invaders?

    I also maintain a sourdough starter and villi culture. Both are not in 100% anaerobic conditions, especially the villi which is not sealed during culturing. Both require LAB to create the lactic acid to preserve the cultures. If the LAB can keep those cultures safe, why should I fear that the LAB in open crocks can’t keep its substrate safe?

    Thanks in advance for your reply. I don’t expect all my points to be answered and I’m sorry for the run on of thoughts. Its just what came to mind after reading multiple blogs about these topics. Once again thank you for your work.

    • says

      Your link to the oil didn’t work for me. I am personally not convinced it is a health risk to use oil – but this is something everyone needs to decide for themselves. If you have a doubt, then don’t use oil :) There are plenty of other options to choose from.

      Mold on hard cheese is different – I do agree that you can cut a chunk of mold off a hard cheese and eat the rest of the cheese. However, in liquids, this is not the case. The roots grow so much more easily and go deeper in liquid. It just isn’t a good idea to simply skim off the mold and eat the rest of your ferment. There are numerous references to this – it’s not my own idea :)

      I was unable to identify the type of mold roots that I saw growing on the bottom of a ferment that had mold growing on the top. Any mold in a ferment is bad. Acceptable cheese mold is of a difference strain and would not grow in kraut.

      Once you have mold in your ferment, it will overpower the LABs. Allowing mold in the beginning stages is setting yourself up for no LABs. The LABs can only grow and thrive if there is no oxygen – the mold is a sign there is too much oxygen available. Mold is able to survive a wide range of pH, so it’s really the lack of oxygen that you can control to prevent mold.

      Yes, there are serious health threats to consuming mold organisms – “dead” or alive.

      There really is no exception when it comes to mold and ferments – I appreciate your thoughtful questions!

      Kruat and sourdough aren’t identical in bacterial composition. I do suggest anaerobic conditions for sourdough as well, though. It is harder to see surface yeast in your sourdough, so you have to be really careful. You are also adding flour and water and mixing it around and taking some out frequently, so it is not a stagnant ferment that can allow spoilage to take root easily.

      As an aside, I prefer making my sourdough with kefir water, just to give it a LAB edge :) You can check that out here:

      • JohnnyD says

        Lea H,

        Thanks for responding.

        I’m sorry the website above did not work for you. It worked when I posted that message, but saw as you saw that it went down. Here’s another reference (that is working atm, skip down to the ‘Flavored Oils’ section about 3/4’s down):

        As for mold, and cheese: What if you didn’t scrape off the mold on cheese and ate it? I’m sure you are correct when you say the roots grow faster in a liquid medium, but that shouldn’t mean that there is no trace of mold or its roots inside the cheese.

        I think we agree that the most important part of fermenting is in the beginning stages, when mold has the upper hand. If mold is allowed to gain a major foot hold before the LAB’s produce their lactic acid and anti-fungal compounds, a ferment can be lost. However this study and others show that once LAB are setup, there really isn’t much to worry about if you get surface mold:

        One other point I’d like to make. I think you may have missed something with your experiment. Since we are pointing to traditional and historical methods in preservation, it is important that we recreate the test ferments as our ancestors have. Our ancestors for the most part, did not make plain sauerkraut. When I mean plain, I mean just salt and cabbage. They used spices and herbs throughout. The German regions for example are known for their kraut with caraway seeds.

        Is it coincidence that caraway seeds are mold inhibitory? My ancestors came from Czechoslovakia and we make our kraut with whole cloves (which are pulled out before consuming). Cloves are also mold inhibitory.

        I’m not debating that a closed system like a Fido jar is a VERY good idea, especially in the beginning of the ferment, but an open crock is maybe not as dangerous if packed correctly and used with a mold inhibitory spice. If you have the energy and time I would love to see a test done with caraway or cloves to see if they can offer a level of protection that plain kraut can’t.

  30. JohnnyD says

    One other comment I forgot to make…

    Has anyone tried using Argon gas that is sold in store wine departments to create an oxygen barrier? The theory is that the argon gas is heavier than oxygen and blankets the surface.

  31. Sarah says

    Re “Mistake #1: You refrigerate your ferment 3-10 days after you pack your jar”

    Does this apply to making just fermented cabbage juice on its own? I.e. juicing a cabbage and leaving to ferment/adding a starter. The GAPS Cooking DVD advises just 5-7 days.

    Many thanks for any advice

  32. Emily says

    What about kombucha? Do you need an airlock for that? I’m dealing with a mold toxin illness, and now I’m worried since I drink my homemade kombucha daily. I only cover it with a coffee filter and a rubber band. I’ve never seen mold but like you say, you don’t always see it.

  33. Sara says

    Question. Trying to find the right lid for the mason jar. WHen you say “white lid” do you mean the plastic or white metal? Two part metal is ok but needs an airlock?

  34. Naya says

    Thanks for this post! I love your website! do these 3 mistakes apply to fermented salsa? I made a batch of salsa yesterday in recycled pasta sauce jars and I have them sitting on my counter. I’m thinking they need to be more airtight…?? Should I open them and do something differently?

  35. Ana Perez says

    Would it be safe and work just as well to cover the jar with 2 cut pieces of plastic grocery bag before I seal the Lid On The jar? I am using a jar that used to have Alfredo sauce in it.

  36. Jaime says

    Would it be okay to eat if the cabbage has lifted from the bottom and the brine is just there..most is covered but the cabbage itself is lifted up to the top of the jar..i’m no sure whether to eat or not.

  37. Missy says

    I am trying the olive oil on top method. All was good for the firs couple of days, but then I notice the cabbage had risen and some was sticking out of the oil. I put more, but is it still ok or should I throw it out?

  38. shane keskeny says

    you mention 28 full days for the north american hard cabbage, but what about other fermented foods? Im making some kimchi right now and I would like to be able to consume it as soon as possible, so that I can enjoy its taste and health benefits. Im wondering if it could ferment fully in a shorter period of time, considering it is made with the softer chinese cabbage also called NAPA. Also the other veggies and roots that went into my kimchi were mixed together in a blender to form a paste, which makes me think this should kimchi would be easily accessible and fermentable for the bacteria and yeast.

  39. elisa says

    hi, i put my sauerkraut in a fido jar and let it sit out for 30 days, however starting from about day 2 the brine was not fully covering the kraut. i didn’t know what to do so i just left it alone. it looks and smells fine, but i am afraid of botulism growing on the part that wasn’t fully submerged. is this a possibility and should i throw it out?

  40. trevor M says

    2 weeks ago I filled two 32oz mason jars with my kraut mixture.

    some of it came above the brine level and I was told that if necessary you can add clean filtered water to just submerge it or remove the stuff above the water. I have removed it typically.

    However, I have NO IDEA what it supposed to smell like. When I just opened them now they are VERRRRRY salty & cabbage smelly. Even now that they are closed the smell is still stuck in my nose.

    Also, they have been in a dark cabinet but it has been hottttt on some days here in Pasadena and also very mild too over that past 2 weeks.

    How do I know when this stuff is done? Will the all the liquid be gone? Do I dump the excess liquid after 4 weeks?

    I made these as a fathers day gift. I hope they come out okay…

  41. says


    I made my first batch of good sauerkraut shortly after reading your Sauerkraut Survivor series on your blog – I bought the Fido jars and made sure to leave it fermenting as you suggested – and much longer than Nourishing Traditions suggests.

    It was the BEST sauerkraut! Your Sauerkraut Survivor was what, over six moths ago(?) – and my ferments are still beautiful and mold free.

    And to add my two cents to the mold issue. . .Mold may not affect you if you’re healthy, but someone with a poor immune system or someone dealing with candida can react totally differently. Ask my husband.

    Because mold spores travel through the air they can be inhaled, and someone who is immune-suppressed or dealing with candida is more susceptible. It depends on your level of resistance, so please be careful about claiming you can peel mold off the top and it won’t hurt you. While you might be just fine, others can get quite sick from it.

    My research and info comes from Candida Crusher – written by a naturopath with over 20 years experience in helping people heal from candida.

  42. Kate says

    I have just made my first batch of fermented vegetables: cabbage mainly with some carrots. The fermentation process resulted in the jars overflowing by the end of day 4, at which point the liquid level was still at the top of the jars. I then put them in the fridge and 24 hours later the liquid level has dropped well below the level of the veg. They smell like sauerkraut -not strong, but distinctive. I haven’t topped up the liquid, and don’t know if I should throw them away and start again. I used celery juice and lactobacilli starter (as per Dr Mercola’s recent post). Is this safe to eat?
    Thanks, Kate.

    • GR says


      I am new to fermenting as well, but I made something that was at least very similar – kraut (organic cabbage), with carrots and red onion, used celery juice rather than salt, left it out 4 days and then refrigerated. That was about a week ago and the jar is almost empty…I’ve eaten up to a cup or more at a time with no ill effects, and the brine has not been covering the veggies while they were in the frig (I don’t think they need to be submerged at that time if you plan on eating them, rather than storing).

  43. Hollie says

    I fermented my cabbage for 4 weeks using a kraut kap. I am concerned because the brine was covering it when I put it in the jars, but it seems that the brine receded over the 4 week period. I took the caps off, put lids on and put them in the fridge. They smell… Like sauerkraut. However, they are not a bright white, but are tan… Not brown. I’m afraid to eat it :(

  44. BrianD says

    Krauts Brine tends to evaporate when weighted with a plate. Adding salt water will eliminate both oxygen and your concerns related to spoilage. Kraut that has turned bad is just that “bad” and not likely to be easily mstaken. Hollie, keep tasting and stay confident

  45. says

    I have read all the questions / answers on this page but,,,,,what I want to know is the SALT….Is iodized salt not good for making kraut ??? I was told iodized salt will make the cabbage mushey ????
    I have made kraut for the past two years now but,, I never paid attention to which salt I used,,,iodized or regular. My kraut always turned out great but now with being told about the salt, I would like your opinion,,,Please.

  46. don ray says

    I ferment the cabbage in a crock for about 6 weeks until it tastes good. My question involves canning the sauerkraut. I understand boiling will destroy the probiotic value, so canning seems to be a problem. Without boiling the kraut, how do I get the jars to seal ?

    • WSmart says

      Tried to reply to your comment but got misdirected and posted a new comment to the article instead. See below for full comment, but I think your point is no brainer for sure. Thinking the food saver vacuum sealer, plus some oil on top, plus cool temps is the way to go.

  47. Ellen says

    I am doing the method of olive oil on top with fermenting carrots/jalapenos/garlic. A few garlic floated to the top and seem to be above the olive oil. Is it ok to remove them if they get moldy since the rest of my veggies are way down in the bottom of the jar in the brine no where near the olive oil ?

  48. Ellen says

    I have read numerous times that the mold that might form on sauerkraut can just be removed or pushed down and it will not hurt you due to the chemical make up of sauerkraut when it is fermenting. Any new info on this theory?

  49. WSmart says

    Exactly, you don’t want to kill the friendly bacteria.

    I don’t know what the best answer is there, but one thing I have mind with kraut here is using a vacuum sealer. I think food saver has a device that fits over the canning lid and can be used to seal a jar, pull out some of the air and create a vacuum. I was thinking this would be good to use for fermenting, but no doubt it would also help to keep the finished kraut fresh. It’s not canning, but if you kept it cool or in the fridge and maybe a layer of oil on top, I think you’d have something comparable.

    Be real, be sober.

  50. Michelle says

    I started my sauerkraut about 2 weeks ago, and it was fine for the ~8-10 days (i’d checked it)…just now I noticed that the brine layer was essentially gone. If I throw away the top layer (it is a little brown), can I keep the rest that was in brine? The rest smells fine and (maybe it is dumb to know this, but too late now!)it still tastes okay.

  51. SophieE says

    I was thinking of creating a one way valve by just topping my jar with a balloon with a pin-prick in it so there would be a positive pressure within the jar so only air from inside the jar would escape and oxygen wouldn’t come in.

    My concern is that there is already oxygen in the jar to begin with… Are you meant to fill it with liquid to the very edge of the seal or is that little bit of air alright? I haven’t made sauerkraut myself yet.


  52. AniKouni says

    I made sauerkraut for the first time and thought everything was OK with it. On the 4th day (yesterday) I ate about half a cup. Right away my stomach didn’t feel so good. I then read your article. The most comprehensive one I found. I woke up in the night feeling like I would throw up. I’m still in bed now feeling very nauseous. What I really would appreciate is if you could tell me if there anything I can do to get the mold out of me? This batch is going to be flushed!

    • Zigged says

      Ani, I also got sick, that’s why I’m reading all these posts. I’m not into making my own – I bought some raw kraut at Mother’s Market b/c “it’s good for you”. I munched some of it, kept in the fridge, exp date is 4/14, then last nite had some more. An hour or so later, gnawing stomach got worse and I had to make myself vomit. I still feel weak next day. Threw it out, noticed some brown parts but rest seemed ok. Sorry but this sounds pretty risky, I’ll stick to my yogurt for my pb. Meantime anyone gets sick if still in stomach, get rid of it – force if necessary. Take antacid and slowly increase your water intake as your tummy will let you to flush toxins out of your system.

  53. ethan says

    The information in this article is inaccurate and misleading. Kham yeast is not harmful. It is often unpleasant and undesirable, but not in all circumstances. Some old-timer Koreans even consider kham-yeasted kimchi a delicacy. I have found that in certain ferments (like fruit-based lactic acid ferments), it can impart an almost cheddar-like dimension to the flavor.

    Furthermore, yeast does not produce acetic acid. Aceto-bacteria produce acetic acid in an aerobic fermentation process as a follow-up from anaerobic yeast fermentation of sugars into alcohol. So it is sugar > alcohol (anaerobic; yeast) > vinegar (aerobic; bacteria). Lactic acid ferments are sugar > lactic acid (anaerobic bacteria). It is a completely different process.

    That said, yes, fill your container at last 75% – 90% full, keep your ferment submerged in the brine, and let it ferment! Don’t be afraid to assess texture and taste! Most lactic acid spoilage is just undesirable (e.g., slimy vs crunchy vegetables) vs unsafe.

    Please stop scaring people! I highly recommend Sandor Katz’ Wild Fermentation as an inspiring and accessible introduction, and, for the enthusiasts, the Art of Fermentation is also an excellent resource.

  54. dawn says

    While the lactic acid keeps the bad bacteria from growing during the fermentation process, the salt and oxygen in the jar or crock initially create an environment where botulism cannot live (aerobic). As the lactic acid begins to form it creates a gas which slowly pushes out the oxygen, but by then enough lactic acid has been produced to lower the pH to an acidic environment where bad bacteria will not survive.

  55. says

    I made a cranberry chutney with raisins, 3 cups of cranberries 1 apple.1/2cup honey on Nov. 11. I just used a wide mouth mason jar with no lock. I don’t see any bubbles in it but it smells good. What do I do. I also cut them all small.
    Thanks & blessings
    Lorraine Fleming

  56. brinn says

    I have my first batch of sauerkraut fermenting. I think it is about 2-3 weeks since we started. I just realized this morning, that the brine is not covering all the cabbage. The airlock bubbled out all “excess brine. There is only a small amount of this brine sitting in the airlock. Nothing appears to be happening. We used a couple of plastic ziplock bags filled with water to keep the cabbage down underneath the brine. There is cabbage that is poking out from under the brine. Does this mean that this whole batch is contaminated? I’m not sure what to think or do.

  57. Calhoun says

    On our third batch of kruat and the first two were great. Our third batch,(this one) has a bad smell. Maybe yeasty like. We have done everything the same. We make it in a 5gal. plastic restaurant bucket with a plate and a large baggie of water to keep it in the brine. Whats the story and can we still rescue and use it. Thanks for all your doing.
    teach peace and tolerance

  58. su says

    If you just want to get information on mold identification, I urge you to make an appointment with a professor at a college (someone with a PhD because legally, they are experts,) that is near where you live. Based on your location, they can help you determine what type of mold is most statistically likely to grow in your home. From here, you will be directed to good field guides, and will have the tools to assess your localized risk.
    I have found that good experts are usually those who list “harvesting and eating wild fungi” as a hobby. They have helped me discover a love and respect for mold, rather than a fear.

  59. Rodney Ginter says

    Hi, I made Sauerkraut for the first time this year. I made it in a beer & wine making bucket. I used 6 or seven heads of cabbage one red. I used Himalayan sea salt and added some horseradish. I put a lid with a fermentation lock on it and waited four weeks. When four weeks came I opened the bucket thinking my sauerkraut would be ready but instead it was like it had not fermented at all the cabbage was still hard like when I first cut it. House temperature was 70 to 75 degrees What do you think I did wrong? Thanks

  60. Andrea says

    Do you know how long it takes for a batch of kraut in a completely anaerobic environment (Pickle-it) to go through all the stages of fermentation so that all the probiotics are mature? I read it takes more like 3 weeks but I’m looking for some solid info. Thanks!

  61. Craig says

    I am new to making sauerkraut, made my first batch 2 months ago using a ceramic crock. Upon completion of the kraut I left it in the crock, covered the kraut with saran wrap and placed weights upon this and have left it undisturbed for the past 2 months. Today I removed the weights and the saran wrap and there is mold around the top edge, approximately 1″ wide… the rest looks good, it is pinkish, but this is because I mixed white and red cabbage together. The crock has been on the kitchen counter the entire 2 months.

    Question: Was I mistaken to leave the kraut “out” as long as I have or should I be able to eat my kraut? And should I now refrigerate the kraut? Or should I start again?

    Thank you

  62. Ashley says

    We have made several batches of sauerkraut now and seem to prefer the red cabbage, which I gather is also the most nutrient rich. The way to do this properly is to invest in a proper ceramic sauerkraut pot that is made for the job and will last a lifetime. No mold and no hassle but it does take a couple hours to prepare a large batch.

    We like to leave the cabbage to ferment for 6 weeks before taking off the lid and transferring to glass jars that are then kept in a fridge. The taste seems to improve over time as it is stored in a fridge and we eat a small bowl full every day.

  63. Carie Starr via Facebook says

    I tried kefir but it didn’t taste good with our goats milk. Now we are brewing Kombucha and find that much more doable for us. We drink it regularly and do 2nd ferment to make fizzy drinks. :)

  64. Mary Spencer via Facebook says

    So when she says mold does she mean black or green mold or does she mean the white bubbles at the top? Or white mold? I was under the impression you could scrape the mold, from several fermentation books I’ve read

  65. Alice Benham via Facebook says

    Is there much point in buying airlocks for your lids, if you can accomplish the same thing with a layer of olive oil?

  66. Brooke Shambley via Facebook says

    Food Renegade, I’ve read your later post where you interview the top fermenting expert and he says it’s okay to scrape off the mold, but then you’ve never revised this earlier post. As you repost it, many people give up on fermenting because they can’t get it “right”. Will you consider revising?

  67. Brett says

    Food renegade is wrong when he says that the optimum bacteria is created in a minimum of four weeks. Perhaps more diversity but not more in quantity. I researched this extensively when I began making kraut. Turns out that some universities have done research on this and they consistently found optimum bacteria count at 7 days at 74-75 degrees. With all due respect to food renegade, I trust a controlled university study much more than some guy taking random samples at home with a microscope.

  68. Andrea says

    I took your advice and bought pickl-it jars to create an anaerobic environment and then left the ferments for 4 weeks.

    I tried them at the end of the week and they tasted great.

    At the end of 4… not so good.

    They were sour but also soggy. They weren’t as crisp and bubbly as they were after just a week. I also noticed they really stopped burping as after the first couple weeks. Are they really better for you at 4 weeks because they taste so much better after a week.

  69. Andrea says

    Brett, would you please include links to some of these studies?

    I don’t care about me or anyone else being right or wrong, just getting to the bottom of it :) Thanks.

  70. Kathryn says

    imust have done this all wrong. I thought i was suppose to cover cabbage with water not allow it to make its own juice its completely covered with water a white film has developed I tasted a [iece of cabbage it was salty not vinegary but I don’t think this is right. Help how do I keep it air tight in the crocks?

  71. says

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  72. Donna says

    Hi thanks for the great info. But I have one question.
    I have just made my first batch of sauerkraut and beetroot carrot and apple . Now that I have them in the fridge the water level is about half way down. So the top is not under any liquid. Is that ok or should I add some water ?
    I had the jars very full with the vegs weighed down with cabbage leaf and a glass shot glass so under the liquid. But they bubbled a lot and I did release the pressure thought I had too much liquid in them. I used fido jars and thought they weren’t working as they weren’t air tight. But they were actually doing what they should – releasing the pressure
    But now I seem to not have enough liquid. Like the store bought sauerkraut .
    Thank you.

  73. Mary says

    Well, great .. (sarcasm)… I am new to the fermented foods “club”, though I have believed whole-heartedly in probiotics, and have consumed yogurt, buttermilk, and kefir, for many years. I recently “discovered” Kombucha fermented tea. And recently I learned about probiotics in fermented foods, was informed that fermented foods are easy to prepare at home, and, as fermented foods are expensive to purchase at health food stores, I decided to make my own, starting with basic sauerkraut. I have read, and googled, and watched youtubes on how-to. I was convinced this is a simple process “anyone” can do. So I made my first batch of cabbage & beet sauerkraut yesterday. But NOW I learn that the “basic process” is NOT healthy, and that I am making 3 (or more) mistakes… … Even if I scrape off any mold that forms I might ingest mold… or worse, perhaps ingest “bad bacteria”… Supposedly I have to purchase expensive airlock systems. My great-grandmother and grandmother did not have fancy airlock systems, yet they made healthy fermented foods — that is, no one died from eating them (as far as we know). ~~~ I am feeling quite discouraged about this…. What is TRUE??

  74. Connie says

    Lea, I have read elsewhere that mold on the surface is an indication that there is mold down in the container, but it seems to me that, just because conditions are right for mold to grow on the surface, doesn’t indicate that conditions down in the container would be hospitable to the mold. I know you said you checked the bottom of the jar and found mold there–did you also sample from the middle of the ferment? Might it not be that mold is able to form on the perimeter but not into the ferment. Might it be that throughout the history of fermentation there was always a bit of mold around the ferments but the amounts were not enough to be harmful because they couldn’t actually penetrate the ferment? These are questions I have come up with over time. Thank you for this great post. I look forward to your response.

  75. Connie says

    I like the idea of using a layer of olive oil to top the ferment, but I would be concerned that a layer of coconut oil, solid in my kitchen in the months it’s cool enough to ferment, would crack under pressure allowing oxygen back into the gap created. Did I misunderstand something?

  76. Connie says

    Hi, I have a question about when you’re putting the layer of olive oil on top. I was under the impression that it wouldn’t expand if I did this, but it still does, so I’ve been assuming that it wasn’t working properly. But perhaps, it is just CO2 in there, and OK to not press back down? Do you just leave more room at the top so it won’t overflow? Thanks!

  77. Katheryn Barrett via Facebook says

    There are other WAPF people who say that probiotic content dies off after 6 days…

  78. Laura says

    It’s self-contradictory to venerate our ancestors and their traditional foods in one breath, and in the next breath, tell us that THEIR fermentation methods are very dangerous. Sandor Katz is globally-recognized as the authority on traditional fermentation, and he says our ancestors used closed crocks, open crocks, and even holes dug in the ground.
    How can you (or we) trust the health-giving qualities of traditional foods if, as you say, one of the cornerstones of every traditional diet of the world has been made “wrong” by cultures all over the world for thousands of years? So we’re supposed to distrust time honored traditions because of your science? That’s precisely what the USDA is doing with “MyPlate”! I distrust so-called science, and much prefer the traditions of my ancestors.

  79. Kelly says

    If I use a fido for sauerkraut, do I need to open the lid at all before 28 days to relieve some of the pressure so the jar doesnt explode? Should I put a layer of olive oil on the top? Thank you!!!

  80. Tricia says

    Thanks for the good information! I just clicked on your link on where to buy fermentation airlocks and vessels, but I don’t see anything like that. (Several other good lists, but nothing on fermentation vessels). Has the list been moved somewhere else? I’m new to fermenting, and really trying to figure out the best way to go about it!

  81. says

    Great post. I have experimented with using mason jars but find using a fido-style jar along with fermentation weights such as Pickle Pebbles (available at and ebay and amazon) take the guesswork out of making sauerkraut at home. Since I made the change I have never had a batch go bad on me.

  82. Erin Horn via Facebook says

    (And I just use salt to ferment, no whey or starter. It may take longer with just the salt, but eh, so what? :)

  83. Sarah Icantthinkofsomethingcooltoput via Facebook says

    haha, this post was such perfect timing, as i just started my first batch of sauerkraut today lol o/ Thank you for all your posts! ^o^

  84. roberta says

    Hi, I just made sauerkraut for the first time. The big Fido (type jar) must have had a crack in it because when I checked it that night, it was leaking all over the counter. I quickly transfered it to 2 other jars I had. One fido smaller jar and a mason jar. I don’t know if it is going to be ok. There was not enough brine so I added a bit of water to cover the cabbage. Since I only had one fido jar (or something like a fido jar) I added a layer of olive oil. Then I put cheese cloth over it.
    I put big leavews on top to hold down the cabbage. (had not read you site yet)

    Questions!! And Thank you for helping me:
    Should I take the big leaves out?
    This is day 2, there is white stuff coming out of the fido jar, I think that is ok? Should I open it and make sure it is still in water and take out the big leaves?
    The cheese cloth is all wet and both the jars are leaking. I am not sure how I would take out the big leaves in the mason jar as the olive oil is on top of all of it.
    Oh my I didn’t think it was going to be so hard. Any help would be apprecated very much. I am really wanting to eat this for myself and my family.
    Thank you!!

  85. Sonja Pokorna says

    Hello there,

    does anyone have an idea, why my red sauerkraut tastes fizzy, after alcohol.
    I fermented for 18 days (the temperatures were very hot – about 86 Fahrenheit) and then I divided the 4 kg sauerkraut into 2 jars and stored it in 2 different fridges. The sauerkraut in the first jar tasted really good but the sauerkraut in the second jar after 2 weeks, stored at about 50 Fahrenheit tastes after alcohol, fizzy. It fermented probably further on. The jar was closed, but the sauerkraut was not submerged in the brine. What happened here? I suffer from severe Candida overgrowth and I am on the GAPS diet – so I don’t want to make any mistakes. Any tip would be appreciated.
    How high should be the storing temperature in the refrigerator?

    I heard that after 3 weeks the fermentation is finished and afterwards the bacteria die out (because all the sugar, the food source had been eaten)
    How long should the sauerkraut be fermented to get the most bacteria out of it but still be on the safe side – esp. when the temperatures are pretty high – like at about 85 Fahrenheit in the summer?

  86. Mandee says

    Thank you so much for these writings on fermentation… I was wondering about the mold issue. Since mold can’t be seen at the beginning of its growth, is there a way to test for it when making saurkraut?

    Thanks again!
    Wonderful Post!

  87. Danny says

    Dumb question, but new to this, when you finally transfer your jar to the fridge, do you remove the air lock and put a normal tight lid back on or just leave it all as is.

  88. Valerie Garcia via Facebook says

    This post was very timely as I just finished making my first ever batch of kim chi using a Harsch stoneware crock and I have questions! I read your wonderful posts often but rarely comment or question but this is a matter of life and death (for my kim chi)!! If anyone can help I appreciate. Here is the thing: I got everything in the crock according to the recipe, but I hadnt read anything about reserving one or two whole cabbage leaves to lay across the top of the veggies and under the weighing stones until a few hours AFTER I sealed the crock up with the water. So I hurried and got a whole cabbage leaf and I OPENED THE CROCK, put it over the submerged veggies, put the stones back and put the top back on and made sure water seal was ok. My question is, DID I MESS UP BY OPENING THE CROCK??! Iam so scared! I just freaked that omitting the cabb leaf on top would wreak havoc on my kim chi and I would only find out weeks later when I cracked open the crock, to my horror and disappointment. Id love some reassurement or the cold hard truth….I hope I didnt mess up here…

  89. Calvin Rooks says

    Hi, I sure liked this article! Is there some way you can be sure if there is mold or not? I have lately been using the glass lid with the wire lockdown and gasket. filling them full and they off-gas and liquid comes out in 2 or three days until its done. However the kraut is not submerged completely in the brine and I cure it for 30 to 60 days. I don’t see any mold and it tastes fine I think. Is there any way to test or know for sure? What do you think, could you e-mail because I’m not on your site much. thanks so much!


  90. Amie says

    Will opening my lid cause the cabbage/carrot kraut to spoil? I have mine in a large mason jar with a plastic lid. Every few days, I take a taste test to see if it is ready. Some bubbles will rise to the surface if I push the kraut down with a wooden spoon. The coloring looks like I’ve seen in the stores.

  91. Renee B says

    I’m confused?? This is the first time we tried making sauerkraut how do we know when the mold is okay in the mold is not okay?? I am getting ready to can it but having second thoughts?

  92. Melanie says

    So, I guess after reading this, I’d better change my method of doing a jar that my cabbage is being held under its own brine by a heavy weight drinking glass under a kitchen towel. I thought I just had to scrape of the foamy scum off everyday. No mold that I can see so far…
    Anyways, I had a question. I have a surplus of cabbage and I want to make it into sauerkraut. However, we can only eat so much sauerkraut so fast. I have a dehydrator that goes down to 115 degrees or less. Can I actually dehydrate my cabbage raw and then rehydrate it and make it into probiotic sauerkraut and have all nutrients intact?
    I’m not sure I’ll get any notifications that you answer this question, so could you please email me your answer instead? Thanks!

  93. Emily says

    Hello all! This is such wonderful information, thanks to Lea for taking the time to do these experiments and show you findings. I have been making sauerkraut fOr some time now but always left the jars open with extra cabbage leaves on top. I’ve read many things on the internet that says you can just discard the leaves and as long as the cabbage is below the brine, it is “safe” however I never liked the idea of it. After reading your suggestions I bought a couple air locks. However all the liquid rose so much that it started coming out the top. I unscrewed the jars to push everything back down but I’m wondering if I’ve ruined the batch. Plus the liquid just rose to the top and leaked out of the airlock again. Appreciate any advice!

  94. Gohar Orozco via Facebook says

    Thanks for this. I have a question regarding mold – I have scraped away the mold and cooked with tomato sauces, does the heat kill the bad bacteria? Also, if we don’t show immediate reaction to bad bacteria, is there a way to see/check if we have a problem after possible ingestion? Also, which organs suffer from it? Is it the liver only or other organs too (asking in order to have in mind when checking on health symptoms). Thanks you!

  95. Alejandro says

    Hi! I am in the middle of my first sauerkraut batch and am very excited/nervous :) even more after reading all the comments because it appears I have done many things i shouldnt have hehe
    After reading some few books about it I just opened my first batch today to see how it was doing… this is after only 4 days. There was many bubbles in the jar so i guess the fermentation was going well. I was using a jar with an airlock but it appears some brine escaped from the side of the lid and therefore not airtight… not sure if thats a very big problem.
    So, my main concern is that, to try the cabbage, i took some of it out, ate it, and also stirred the cabbage a bit around. Somehow I realized that after eating some of the sauerkraut there wasnt enough brine left to cover it completly again. To achieve this I just added some water in. I think i had put too much salt initialy so therefore i didnt prepared water with salt but just added pure water. Is this ok or did just ruined it??
    So what happens after we start eating the sauerkraut? how do we keep it? and is it a big problem that some brine escaped through the lid? should i have it tighter?
    Thank you very much for your help!! really need support with this :)


  96. Jerry says

    I’m always forgetting to replace the water in the rim of my Harsch crock. Any thoughts on using an oil instead of water to avoid evaporation? I could put a towel over the whole thing to keep dust, etc. out.

  97. Karen says

    Hi, can you tell me if I should leave other fermenting vegetables (other than cabbage (sauerkraut)) out ‘on the bench’ for 12 weeks before refrigerating, like you recommend for sauerkraut? Thank you

  98. jasmine says

    I have a 10-Litre Harsch fermenting crock. After I leave my food (let’s say kimchi) ferment for four weeks, what should I do with it while I take months to eat it? Should I store it in individual jars outside or inside the fridge?

    • says

      Hi, im in the process of making my first batch in glass maccona coffee jars…. they have a plastic rubber inside the glass lid however im not sure if thats enough to keep the air out. Im storing the jars in my garden shed in the backyard (about 25 degrees celcius). Its day 2 and when i went out to check on them i could actually hear them fizzing…. so i put some heavy bricks on top to keep the pressue in.. is that ok? This is too fun… i keep thinking they may explode!

  99. Ben says

    I’m getting mould after putting the sauerkraut in the fridge for a few weeks (near the top of the jar where the cabbage dries out). Any tips on avoiding this?

    • Julie says

      Never mind… I see the discussion about this issue in the comments above. I wasn’t able to activate the comments earlier on my mobile. I would delete my comment, but I don’t think I can.

  100. Ellen says

    All the other websites say a bit of fuzzy mold on fermented veggies can not hurt you that spores can not grow down-the salted brine prevents this and it is perfectly safe to scrape and eat if all smells and tastes fine. Any update on this theory?

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