Are Mason Jar Ferments Safe?

Recently, the internet has been in a tizzy over whether or not mason jar ferments are truly safe. Perhaps you’ve read other bloggers struggling with the issue. Or, maybe this post is the first you’ve heard about it. Or maybe you’re one of the few who’s wondering why I’m even talking about fermentation at all, let alone something called mason jar ferments.

Fermented foods pre-date refrigerators, hot water bath canning, and modern preservatives. They are one of the ways traditional food cultures “put up” their summer harvest for the winter. Every continent has examples of these naturally fermented foods. There are vegetable ferments like sauerkraut, kimchi, cortido, and dill pickles. There are dairy ferments like yogurt, kefir, and cheeses. We even have a tradition of preserving our meat through lactic acid fermentation in old-fashioned brine curing of sausages, hams, and even bacon.

The basic premise behind these traditional fermented foods is this: lacto-bacillus bacteria cultures take over the food, producing lactic acid. This not only increases the nutritional value of the food (often increasing some vitamin content like B-12 and C by 300-600%!), but it also preserves the food for months or even years while producing a pleasantly sour taste. In modern, industrialized food production we fear the inconsistency of such traditional natural ferments, so we mimic that sour taste with vinegar while killing off all bacteria using hot water bath or high-pressure canning methods. While this gives us food that tastes almost like the traditional good stuff (or at least it tastes sour), it also gives us dead food devoid of the extra nutrients and healthy beneficial probiotic cultures found in a living, naturally-fermented food.

When Sally Fallon Morrell published her cookbook Nourishing Traditions, she wanted us to re-learn the value of these naturally fermented foods. She wanted to present recipes that made lacto-fermentation simple, to use tools and ingredients that the average person would have on hand.

Ferments in her cookbook are straightforward. Vegetables or other foods to be fermented? Check. Salt? Check. Other contributing spices or herbs? Check. Mason jars? Check. And, if people wanted to add a starter culture to the ferment to help make sure the lacto-bacillus bacteria could take off quickly, she recommended using whey strained from yogurt or raw milk.

So, many of us took her instructions and dived right in.

What was your first ferment? Mine was sauerkraut, followed quickly by a raisin chutney that knocked my husband’s socks off. (He loves that stuff and would eat it at every meal if I kept him in a constant enough supply of it.)

So, what’s the big controversy?

Recently, the blogosphere has erupted with a slew of posts asking the big question: are mason jar ferments safe?

The basic argument behind the critique goes something like this:

1. Lacto-bacillus cultures need an anaerobic environment to thrive.
2. Mason jars don’t seal well enough to remove the oxygen from the ferment.
3. Therefore, the fermentation that happens in mason jars doesn’t produce enough quality lacto-bacillus cultures to reap all the health-benefits of fermentation.

The proof that mason jars don’t seal well enough is that some ferments don’t “keep” well. The surface of the ferments may get moldy, and molds specifically thrives in an aerobic environment. So, if it’s aerobic enough for mold to grow, then it’s too aerobic for an authentic anaerobic lactic-acid ferment. Furthermore, that mold has grown spindles throughout the ferment, not just on the surface where it’s actually visible. So, even if you scrape the surface mold off, you’re still eating mold when you eat the ferment.

To correct this problem, the argument says we need specialized fermenting equipment like Pickl-It containers or Harsch crocks which use vacuum seals to remove the oxygen from the fermenting vessel. These containers can be expensive, so the average person is left wondering if they should even keep fermenting at all. If mason jar ferments aren’t safe, but it’s all they can afford, should they just abandon making their own fermented food? Should they save up and dish out the cash for the expensive equipment?

Are Mason Jar Ferments Safe?

I couldn’t deny the logic of the argument, and I wondered what puzzle piece I was missing. After all, these are new, specialized vacuum-creating fermenting vessels. How did we successfully produce lactic-acid ferments before they were developed? Sure, a few traditional cultures did interesting things like sealing their ferments with fats or oils, burying them beneath the ground, etc. But other successful traditional cultures fermented in open vats. If mason jar ferments aren’t safe, then these open vat methods of fermentation weren’t safe either. And, that, of course, would mean that the way we’ve been successfully fermenting foods for thousands of years is dubious.

I have a hard time critiquing traditional methods of food production, particularly when my entire food philosophy is based on a return to traditional, real food.

So, I decided to ask a few people I consider experts their opinion.

The first person to respond was Jenny from Nourished Kitchen. Jenny, you’ll remember, has an amazing online class available called Get Cultured! How To Ferment Anything. I took her class last year and was blown away by the hundreds of easy recipes allowing me to ferment everything from ketchup to salsa to sweet pickles.

Jenny said this:

If your ferment rests below the brine level IT IS IN AN ANAEROBIC ENVIRONMENT. The brine itself makes it an anaerobic environment. End of story. Folks were making ferments for thousands of years before the Pickl-it was developed a few years ago. They used crocks, stones and brine … to create an anaerobic environment.

The next person I asked was Wardeh from GNOWFGLINS. Wardeh recently had a book published on the subject of fermentation (which I’m hoping to review for you guys in the not-too-distant future) called The Complete Idiot’s Guide to Fermenting Foods.

Wardeh said:

I prefer a good-better-best approach. Completely anaerobic is best for many ferments, so ideally one would want to provide that if one could. Does this mean that it is all or nothing? Does this mean one can’t ferment in not-ideal containers or with other barriers to airflow? Does this mean you can’t achieve anaerobic in mason jars? I don’t think so. Often Pickl-It people tell others to use keep using mason jars until they can afford Pickl-Its. This recommendation says to me that they know that fermentation occurs in less than ideal (to them) situations.

One of the Pickl-It folks’ arguments is that even below the brine there’s an exchange of oxygen with the air, and this interferes with the proper production of lactobacilli. Although I haven’t been in a lab to test it (nor will I), my feeling is that with a starter culture provided, salt and acidity at the right levels, the lactobacilli are going to thrive just fine. I think we do know this from experience because people ferment sauerkraut (even in the open air) and it lasts in cold storage without spoiling or getting moldy. I’m not saying open air is the best approach — there is greater risk of spoiling — but certainly it can be successful.

Wardeh even shared a few arguments from her local WAPF email list. A couple seemed worth mentioning to me.

First, carbon dioxide is heavier than air. Anyone who has worked with natural ferments before knows that naturally-fermented foods produce carbon dioxide. That’s why the end result is nice and fizzy. Because carbon dioxide is heavier than air, it will sit on top of the surface of the ferment and act as a barrier between the ferment and the oxygen in the air. The biggest trick with this is to not move the ferment or allow for air movement. So, a simple sealed container like a mason jar ought to be sufficient so long as you don’t open it frequently during the fermentation process. I’m not sure just how much protection this offers, but it certainly helps explain why some people (like me) have never had mold grow in their long-term mason jar ferments.

Second, if you really really want an anaerobic environment, just do it the old-fashioned way and pour a thin layer of olive oil or coconut oil over the top of your ferment. The oil top layer will keep oxygen off the ferment’s surface. When you’re ready to eat the ferment, the coconut oil layer will pop right off as a solid, removable hunk as long as the temperature is below 76F. If you use olive oil over something like a fermented salsa, you can just mix it right into the ferment for added flavor.

The final person I sought out was Sandor Katz, author of Wild Fermentation and the soon-to-be-released The Art of Fermentation. Sandor is basically the world’s leading expert on traditional fermentation. He’s traveled the world learning from traditional cultures, and he’s taught fermentation workshops everywhere from California to Italy.

He apparently received a lot of questions about this topic recently because he chose to address it publicly on the Wild Fermentation Facebook Fan Page. This was his response:

I hear that much controversy is brewing on the internet over vessels for fermenting vegetables, and the implications of whether or not they are totally anaerobic. I have made hundreds of batches of kraut in all sorts of vessels (most of them open crocks), and I have witnessed, consistently, that it doesn’t matter. Each vessel has advantages and disadvantages. No particular type of vessel is critical. People have been fermenting vegetables for millennia in crocks open and closed, in pits and trenches, in sealed and open vessels. It can be done many different ways. The only critical factor is that the vegetables be submerged under brine.

Whenever vegetables are submerged under brine, lactic acid bacteria (which are anaerobic) develop. Whether or not the vessel protects the surface of the ferment from atmospheric oxygen, the microbial development under the brine is anaerobic lactic acid bacteria. In the vocabulary of microbiology, lactic acid bacteria are “facultative” in that they do not require oxygen, but are not inhibited by its presence; in contrast, certain other bacteria (for example Clostridium botulinum) are “obligate” anaerobes that require a perfectly anaerobic environment.

The only difference air exposure or lack thereof makes is whether aerobic organisms like yeasts and molds can develop on the surface. The barrel of kraut I have had fermenting in the cellar for six months now is good and sour, and I have been eating from it and sharing it widely for months. Each time I remove the cloth tied down over it, and the jugs of water weighing it down, and the two semi-circular oak boards that rest upon the surface, I skim off a moldy layer around the edges and down the middle, wherever the surface was exposed to air. I toss the moldy layer into the compost, and the kraut beneath it looks, smells, and tastes wonderful. Many people have reported how good it made them feel and not a single person has complained of any problems from it, ever. The brine protects the vegetables from the aerobic organisms that grow on the exposed surfaces. The ferment is a lactic acid ferment, even though the surface is aerobic. Surface growth should be scraped away because if it is allowed to grow it can diminish the acidity of the kraut and affect flavor and texture, but if you keep periodically scraping mold away, the ferment beneath is fine.

I have also fermented in Harsch crocks, Pickl-Its, Mason Jars, and many other types of vessels. Mason jars become highly pressurized if you fail to loosen them to release pressure. Even if they are not perfectly airtight, they permit little airflow. Many times I have witnessed carbon dioxide force its way through the airtight seal by contorting the tops to provide an escape for the pressure. The various air-locked designs that allow pressure to release while preventing air from entering the system are generally effective at preventing aerobic surface growth. Yet still I generally do not use them because I love to look at and smell and taste my krauts as they develop, and each time you open an air-locked vessel you defeat its purpose, allowing air in. The vessels are effective, but are not well-suited to my desire to taste at frequent intervals. Different vessels suit different needs and desires. No one type of vessel is essential for fermenting vegetables. I have had success using every type of vessel I could think of. As long as you can keep vegetables submerged, lactic acid bacteria will develop. The process is extremely versatile.

You can see from his response that Sandor isn’t afraid of mold. He just scrapes off the surface mold and enjoys what’s underneath. Even if the argument that mold produces “spindles” throughout the ferment is actually true (which it may not be, given that the environment below the brine really is anaerobic), why should that bother you? If you eat cheese, you eat mold. Some cheeses even attempt to cultivate certain kinds of mold (like blue cheese). Surely the benefit of eating a probiotic, extraordinarily flavorful, traditionally-prepared ferment outweighs any sort of ick-factor you may have over the presence of small amounts of invisible mold?

So, What Should You Do?

You can see that the overwhelming opinion of people-in-the-know is that mason jar ferments are safe. And, if you’re still hesitant about mold growth on the surface of your ferments and really want to prevent it no matter what, then opt to use oil on top of your ferment. It’s cheaper than an expensive crock or Pickl-It container, and it’s just as (if not more) effective.

If you’re new to fermentation, I highly recommend enrolling in Get Cultured! How To Ferment Anything. It’s currently on sale again for more than $50 off it’s regular price through May 22nd. The e-course is even recommended by fermentation expert Donna Gates, author of The Body Ecology Diet.

For more information about the class, click here.

(sauerkraut photo by johnnystiletto)


  1. says

    This is interesting – I had no idea there was any controversy about mason jar ferments at all. Of course, I’ve just made my very first batch of a fermented food – kimchi. I have problems with casein, so I just used salt, and packed it all into two quart-sized mason jars and allowed it to sit on the counter for 3 days before sticking it in the fridge.

    My husband and I love it – we’ve already gone through one jar and it’s interesting how the taste and texture develops, the longer it ferments. I gave no thought to anaerobic conditions or any of the rest of it, and have not had any problems with mold or off-putting smells or flavors. We’ve been excitedly discussing what will be our next ferment – I was thinking sauerkraut, but now I’m thinking the raisin chutney, especially in light of how much your husband enjoys it.

  2. Celia says

    I never knew there was a controversy either. I actually made my first batch of kraut with a method in Martha Stewart Living, of all publications. (It called for mason jars.) I find it the most reliable method for me, as I usually have multiple ferments going in my kitchen and limited funds. No problems yet!

  3. says

    You have put in to words all that I have instinctively, and based on biology & anthropology, felt is true. Thank you. I look forward to the continued charitable conversation between the knowledgeable lovers of ferments.

  4. says

    I didn’t know I needed this information, but I really do! I have been lacto fermenting for a long time in mason jars and while sauerkraut is always successful, I’ve been plagued with the occasional mold and getting really frustrated. I’m going to take Wardeh’s recommendation and start adding a layer of coconut oil to the top of my ferment. Thank you so much!

    • KristenM says

      Mold has never once been an issue for me, even without the oils, and I prefer LOOOONG sauerkraut ferments. I like it after 3-6 months when it starts getting softer and less crispy. That said, the most important thing is to keep the cabbage submerged beneath the brine. I think the oil tip is useful, too, although I’ve never tried it.

      • Josefina says

        Thanks for the tip! I love soft and deeply flavored sauerkraut–not the crispy, barely fermented stuff I find at the coops, which I can’t even digest. After reading this, I was going to take the time to ask what makes it nice and soft. Seems I don’t have to!

        3-6 months is a long time, but I’m patient when it comes to good food:). How often do you need to check on it to ensure the cabbage stays under the brine? How do you manage to have a mold-free surface? What type and size of container to do you use?


        • KristenM says

          Well, even after 3-6 months, it’s still crispy. But it’s not CRUNCHY. Know what I mean? It’s still not going to be like store bought stuff that’s been boiled to death.

          I use mason jars when I do sauerkraut. I put a cabbage leaf across the top of the veggies, then a shot glass full of water on top of that to weigh it down. Then I make sure there’s at least an inch or so of brine above the veggies.

          I’ve never had mold, but I also don’t fiddle with my ferments the way Sandor says he does. I put it in the jars and immediately put it into storage, not moving it or opening it again until I’m sure I want to eat it.

          • Josefina says

            Thanks! I like the idea of not fiddling with my ferments to:).

            When I lived in the US I used to buy a brand of sauerkraut that was ground up rather than shredded. Since perhaps it’s impossible to get that boiled texture, that I actually prefer, I wonder if grinding the raw cabbage would be doable in a home setting. I had shredded sauerkraut going at home for about 3 weeks once and it did loose its crunchiness, but I still had some difficulty digesting it. Possibly cause of my jaw misalignment–I can’t break it down so well. Anyone experimented with this? A note in NT comes to mind, where Sally cautions against chopping beets too fine for kvass as it would ferment too quickly, producing alcohol.

            • Allan Moss says

              You may want to try hot-water processing following your natural ferment. You will lose some nutrition, but you’ll get the natural ferment flavor and the shelf-stable texture. Just a thought. If you do this, be sure to follow the cold pack processing times when canning.

            • LaDawn Wells says

              I rather like the crisp texture but to keep it from getting mushy I was told to put either an oak tree leaf or grape leaf in the jar as the natural tan in in the leaves keep the vegetables crisp. However, I have seen a YouTube video of cabbage being put through an augar juicer grinding it and fermenting it in the mashed state. It is topped with a cabbage leaf and submerged in a glass jar in the juice and salt brine. No need to worry about alcohol – beets are high in sugar so they need to be quartered to slow down their ferment. Here’s the video

  5. says

    Thanks for this write up! I had been putting off making another batch of kraut because of this controversy. Now, I think I am going to (happily) go shred some cabbage, pound it, and start the process. My kids sure loved the real kraut when I made it.

  6. says

    After mulling over the arguments, and realizing there is some truth to all sides, I made a no cost change in the way I ferment. This can be done in any container.
    I have done the old bag of water on top method, and always had trouble with it happily bubbling over, no matter how I did it.
    Sealed jars work most of the time, but I lost my entire seasons kraut last year.

    I took two plain crocks that I have, with loose fitting lids.
    I made my kraut, packed it in, the laid plastic wrap over the top. Pressed it in to cover all surfaces, and the pressed the outside well, making sure there were no obvious air bubbles.
    I filled the little well left with water, added a rubber band to the outside, and popped on the lid.

  7. says

    We have a 2 gallon fermenting bucket that we bought from a home brewing store – since my husband also brews his own organic whole grain beers. Then we store in mason jars after the fermentation. We haven’t had the mold issue, but then again we don’t keep it on the shelf for very long. 😉

  8. Shauna says

    Thank you so much for such a comprehensive look at this controversy – very enlightening and helpful. I have used both mason jars and Pickl-its. While I feel I get a much fizzier beet kvass (my only foray with the Pickl-it so far) it does not make up for the price difference. I appreciate your work on this.

    • KristenM says

      You’re welcome. I’m not anti Pickl-It by any means, but I do take offense at the idea that it’s the only safe way to ferment and know you’re getting a good lacto-bacillus fermentation.

  9. says

    Like the other comments, I had no idea this was something to fear. My first exposure to fermented foods was through a friend who made a down and dirty mead in a food grade bucket with berries, honey and water – no boiling, no measuring, no covering, nothing. We just stirred the fabulously fizzy concoction every couple of days. I was instantly hooked. I picked up a copy of Sandor’s Wild Fermentations and went on to create many a ferment in all manor of open containers, never giving a thought to potential harm. I’ve never once encountered mold, even in my humid environment. Thanks for sharing some of the background science and other opinions on the matter. Sounds like raisin chutney may need to be the next fermenting adventure.

  10. Taj says

    Thanks for the info. Pleas share the recipe for Raisin Chutney!

    Also, could anyone share what some of the best ways to keep your kraut submerged when using mason jars, other than the oils on top as mentioned above. I normally just put a lid on the jar and after three days or so refrigerate and begin eating. I am a newby to all of this.

    • Melissa says

      The last time I made a batch of kraut, I used one of the leftover outside leaves to cover all the shredded cabbage, sank it down in place so that all the vegetables were covered in brine, and then wedged a shot glass between the leaf and the lid to keep everything submerged. This was using a flip-open glass jar from ikea. I would open it just a bit each day to release the internal pressure (and, boy, did it bubble up). First kraut I ever made, and it worked like a charm.

    • Allan Moss says

      We went to the beach and found some nice flattish, smooth granite stones that barely fit the opening of the jars. Cover the kraut with a couple layers of whole leaves and push the rocks down on top. Use two or three rocks and wedge them under the shoulder of the jar so they keep the kraut submerged. I also do this with my pickles. I once saw a pottery kraut crock designed for open fermentation. It had a loose-fitting stoneware top held down with wire bails (like the old beer bottles, but upside down) It rested bout 2 inches below the lip of the crock so could be maintained fully submerged. If I had been a pickler at the time I definitely would have bought it.

  11. Carol says

    THANK YOU for this!! I had read this on another blog and commented on how silly I thought it was. Those trying to sell the products are going to give compelling arguments for why you NEED their products. This is their job. But, as you said so well, fermenting has been going on for so long without these newfangled items. A little mold doesn’t bother me and is likely to be good inoculation! Most of my ferments work beautifully!! Thanks for the dose of reason and logic here! :-)

  12. says

    KerryAnn at Cooking Traditional Foods goes into very deep detail over why the specific fermenting vessels are superior, including but not limited to how she herself feels health-wise. While I personally have no experience with the Harsch or the Picl-it, I am very strongly considering one for kraut & sourdough, both of which I’ve had issues on & off with mold. I will continue to make my buch, DK & WK in a capped bottle or jar, because that’s what works for me.

    I say try them yourself if you can afford to, to make your own wise decision. Until you do, all you’re doing is trusting one person over another, and that person will not be yourself. You’ll never know until you try it yourself, something I am in the process of working on. Otherwise, I am also along the lines of good-better-best.

    • KristenM says

      Good-better-best seems like a reasonable way to look at it, and I can see the merits of using a specific vessel like the Pickl-It.

      That said, I think it’s unfair and WRONG to say that these new vessels are the *only* right way to ferment, the *only* way to ensure a therapeutic lacto-ferment.

      If a Pickl-It can help you reduce mold and you want to experiment with it, then by all means DO! I’m all for nifty kitchen tools that make my life easier. Just don’t tell me that the nifty new gadget is the only way to do things right, especially given the weight of history.

      • says

        You’re absolutely right. I’m not telling you (or anyone) that a certain way is the only way.

        Quite frankly it pisses me off to read that if you’re not doing this or that, then you’re just wrong & aren’t doing anything good. Lord knows I keep reading a lot of that all over the web from some certain bloggers that think they’re God. I do what I can afford. I ONLY do the best I can, and if someone else doesn’t like that, they they should just be thankful that they’re aren’t part of my family. I’d hate to do SO wrong for them. No one deserves to tell me something is the only way & I wouldn’t dare make mention, politely, of someone that did.

        Family, friends & love first. Then food. Always.

  13. Rachel says

    Wow! Thank you sooo much!!!! This is what I’ve been pestering about and complaining about this whole time to the other bloggers who were pushing the Pickl-its. It just seemed soo strange that all of a sudden this specific company was “the only way” to go. I asked for someone (anyone!!) to contact Sandor Katz and others on this matter and now it’s finally happened. The answer is completely satisfactory and exactly what I expected it would be. Even congruent with what my chemist hubby said which was that water (brine) provides an anaerobic environment. So again, THANK YOU!!!!!

  14. says

    Another great post from the Food Renegade! Thank you so much for this information. I appreciate your level-headed and well-researched approach in all of your posts. It makes your information much more reliable than many other real food bloggers out there.

  15. Emma says

    Its not really about mason jars, it’s about aerobic fermentations being safe and effective, which you don’t really explain :(

    One could drill a hole in the top of their mason jar lid and pop in an air lock for $3!

    • KristenM says

      I think I *did* explain that in my 1-2-3 argument above. Plus, I repeatedly said (both in my own words and using the words of others) that if the vegetables are submerged beneath the brine, it’s NOT an aerobic fermentation. It’s anaerobic. Only the surface is aerobic enough to allow something like mold to grow, and even then it’s not all that likely if you take proper precautions. Plus, it can easily be prevented by using a thin layer of oil across the top.

      • EmmaBlue says

        Thanks for the tip Rick.

        I found both the title and bullet points of the article misleading, it should be called Are Open Air Ferments Safe or Are Aeorobic Ferments Safe?
        Since this is not something specific to mason jars, but any plastic or glass container with an open air fermentation happening. And it also has that shock value because most people use mason jars!!! Reminds me of Time magz Are You Mom Enough?

        I appreciate the awesome dialogue this article started and I look forward to blogging about it in more simple terms.

    • Josefina says

      As for effectiveness of an ‘open’ jar ferment, the comment by Sandor Katz does a pretty good job explaining the science behind lactic fermentation. They don’t need oxygen, but are not inhibited by its presence. Now, looking at this again, it really doesn’t say whether ‘facultative’ means that these bacteria would grow more optimally or not in the presence of oxygen. Just that they aren’t inhibited. But science aside, being that people are obviously able to produce well fermented krauts without using air-lock systems, I’d say the bacteria can indeed thrive in open air vessels.

    • Rick says

      Hi Emma.

      You CANNOT just drill a hole in a metal mason jar lid. It will rust into your ferment. Use a Tattler plastic lid for that, it works like a dream. I use a #4 rubber stopper with my airlock.

      • Emma says

        Thanks for the tip Rick.

        I found both the title and bullet points of the article misleading, it should be called Are Open Air Ferments Safe or Are Aeorobic Ferments Safe?
        Since this is not something specific to mason jars, but any plastic or glass container. And it also has that shock value because most people use mason jars.

        I appreciate the awesome dialogue this article started.

  16. Lisa says

    While I agree with the overall summary that you can safely ferment in mason jars, Jenny from Nourished Kitchen is incorrect. Water contains dissolved oxygen. There is a constant exchange of gases at the surface of the water to maintain equilibrium.

    I have a few Pickl-It jars and absolutely love them. We are using ferments therapeutically, not just as a delicious food, so I appreciate that I am maximizing the LAB population.

    A layer of oil is a great idea. I’ve done that with kefir but never thought to try it with veggie ferments.

    • says

      If the ferment is not actively exposed to air it is fine and will support LAB fermentation and the solids resting below the brine won’t mold. I should have elaborated.

    • says

      Incidentally, when I contacted Donna Gates about this issue (who uses and recommends ferments therapeutically) her sentiments echoed my own: if the solids of the ferment are submerged in brine, you don’t have to worry about airborne yeasts (or molds).

    • KristenM says

      About using ferments therapeutically and maximizing the LAB population, I appreciated Sandor pointing out that lacto-bacilli are not obligate anaerobes.

      That means the presence of oxygen won’t hurt them or hinder their proliferation. They just don’t need oxygen to multiply.

      What does that mean for us? No particular method is going to maximize LAB population. So long as the vegetables are submerged beneath the brine, the ferment is going to happen. The only thing that might increase the LAB population is fermenting it for a longer length of time in a warmer environment, as this allows more growth and bacterial proliferation to happen.

      The only difference a container like a Pickl-It might make is reducing the chance of growing mold or other undesirables on the ferment’s surface. I don’t think it’s possible for a vacuum sealed container to actually help produce more bacteria, given the nature of how these bacteria reproduce.

  17. says

    I’ve been quietly listening to this debate all over the internet with amusement. I didn’t think there was much to worry about. I have been fermenting for 15 years and have never had any problems with mason jars. Mold spores, yeasts and bacteria are floating around in the air all day, you breathe them in every second. I don’t see how a couple of mold spores in your vegetables could be that big of a deal. I tend to listen to ancient wisdom, and my own body on these issues. I feel excellent and never get sick, you can’t argue with that!

  18. says

    I appreciate that you’ve pulled information together from multiple sources. I’m with Wardeh on this one. In an ideal world, one would use the fancy fermenting containers to get more consistent results, but people have been fermenting for a long time in many different containers in many different environments, and I’d hate to see people avoid fermenting entirely because of equipment concerns.

    I hope that people can agree to disagree without getting ugly about it.

    • KristenM says

      That’s one thing these specialized containers seem good for: ensuring consistency of results.

      I don’t think people will get ugly. We’re all rational adults here, right?

  19. Ann says

    I didn’t know about this controversy, but my family has been canning fermented foods in mason jars for as long as I can remember . My mother who is 84, still does and so do I. Just use clean jars and new lids. For heaven ‘s sake, people have become so afraid of homemade food. Propaganda from corporations so we buy their premade food perhaps?

  20. says

    If you’re going to twist my words, you could at least provide links or extended quotes including context so people can judge it for themselves. Very poor work. I have NEVER said there is only one way and that one post was a post in a long series discussing how different environments effect outcomes in fermentation.

    • KristenM says

      Please don’t take this post personally. I’m not twisting your words; I’m not even quoting them. I’m not responding to you personally or your series of posts. If I were, they’d be quoted or linked to.

      Rather, I’m responding to emails readers have sent me as well as a host of other blog posts readers have shared where they are doubting the efficacy of fermenting in mason jars to the degree that they’re swearing off ferments until they can buy “the right equipment.” They’ve lost their confidence in fermentation because they wonder if it’s even worth doing if they can’t “do it right.”

      My goal is to encourage those readers to keep fermenting, even if all they have is mason jars! I don’t want them to stop just because they mistakenly believe there’s only one right way to ferment.

      • says

        Yes, your reply is personal because the source of the controversy was my posts. You didn’t even address the original arguments or issues. You did a very good job of setting up and knocking down a straw man, a distraction, and not addressing the real facts in the matter.

        • KristenM says

          Like I said before, if I were addressing your series of posts, I would quote them and link to them. Since I’m not, I didn’t. I’m sorry that you’re choosing to take this personally when it’s not intended that way at all. And I’m not setting up a straw man (particularly since I’m not arguing with you), merely repeating what numerous readers have emailed me asking about. I’m trying to set minds at ease and restore people’s confidence in fermentation — nothing more, nothing less.

        • J R says

          hi KerryAnn,

          the source of the controversy may have been your posts but it has since gone way beyond you. i’ve never heard of you or your blog but i’ve heard of this issue. ‘the source’ as i know it is a GAPS group and i heard about it from another GAPS group. and nobody ever mentioned you or your blog.

          so, lay off of kristen. she was simply answering reader questions.

          if you had come on here with a different attitude i would have been inclined, much as i like argumentation, to check out your original posts. but as it stands now, i’m not going out of my way to read anything else you’ve written.

          • says

            Sadly, I have to agree with J R. The attitude that is being presented is way out of line, and is not at all healthy for the poster, never mind any of us.

          • Debra E says

            We don’t know the blogging relationship between Kristen & Kerry Ann but it does sound like Kerry Ann is responding this way because she feels that all her research, science, and facts she put into her post are being attacked. Wouldn’t most human beings respond in like manner at feeling attacked? I have read Kerry Ann’s posts on this subject and they pack WAY more info on the science behind the importance of anerobic than this one does. And it’s not just one post. She continues to research and lay out the information. It’s not just her opinion, it’s science. She doesn’t get a kick-back from Pickl-it, she stated that very clearly. I say recognize why she might have responded in this manner and give her posts a read.

  21. Jami says

    Thanks so much for this post! I have been following the whole specialized vessel is on the only way to ferment dialogue and was feeling pretty torn about the whole thing. I have been fermenting for the last 5 years and love it. I’ve never had anything “go off.” I took Jenny’s e-course on fermenting, I thought I had a good handle on it. Then stuff starts popping up about this method not actually creating a ferment but a brined product, I was feeling a little confused, but it just didn’t seem to completely add up to me. The Harsch and Pickl-It are fairly modern products, and not everyone in antiquity had access to such contraptions. I certainly cannot afford them, and the advice from one blogger was to step away from Mason jars and just not ferment if you weren’t using one of the specified products. Thanks for the info, and for input from Jenny, Wardeh and Sandor. I wasn’t ready to step back from mason jar fermenting, but this certainly puts some pep back in my step!

  22. Simon B. says

    Thank you for the very informative article. We have been very successful (as Emma earlier suggested) drilling a hole in a mason jar plastic storage lid and adding a three-piece airlock (99 cents) held in place with a plastic grommet (50 cents) from the brew store (same setup as used in a five-gallon brew bucket). For larger batches, we use one-gallon food grade buckets with the same airlock setup.

    Using two (food grade) buckets the same size, by cutting the bottom off one (with a 1/2″ – 3/4″ ‘flange’) you will now have a tight fitting ‘lid’ for the other to keep the solids submerged and away from airborne yeasts (just add a weight to hold it down).

  23. says

    I find it interesting and amusing that the people you checked in with have no science background in biochemistry or fermentation – and several have learned from Sally Fallon – who has a degree Journalism I think…I need to confirm – but definitely not in biochemistry…
    Same with Sandor Katz – the other folks you referred to are people I believe learned from these two main sources…
    as I did – until I started learning about fermentation from the actual field of biochemistry and from folks who study this science….it’s a matter of chemistry really – mason jars are NOT TRADITIONAL methods of fermenting by any stretch….

    Did I use these when I started out – of course – until I learned more – and now consider it unethical to advise folks to use these to heal their health issues…

    Please keep an open mind and question question question – before giving your health rights away to someone one who doesn’t give you the full story…
    I would only recommend a closed air system for most ferments (not vinegar, kombucha or natto)
    Use a pit, use animal skins, use a crock sealed – use a pickl-it – come up with something even better…but be careful not to just fall onto this “mason jars” are safe….a lot of folks feel raw milk isn’t safe – now that is traditional and chemistry can prove why it can be better for us – given it is clean and from grassfed pastured animals…

    • Jeanmarie says

      Lisa, are you under the impression that one has to have a degree in biochemistry to be expert in fermentation, or that a degree in biochemistry would necessarily make one expert in traditional lacto-fermentation methods? Surely biochemistry has something to teach us about why fermentation works or what is happening during the process, but experience is also a great teacher.

      • says

        yes to some of your question – it seems like people are willing or want to hear that unsafe methods are ok without investigating the facts – there is a science as well as an art to fermentation – experience is not a great teacher if you keep practicing open air ferments when not appropriate – it may taste fermented – but it is more likely brine or salt cured – not full of probiotics – which is why many of us are drawn to fermentation – not just for preservation and taste…that’s whay I am concerned with blanket statements that mason jars are safe for everyone – not true.

        My gut and many that I teach cannot tolerate these open air ferments – it is not a pleasant experience when you get sick…and it defeats much of the goal of trying to heal the gut as well….especially now that we are learning that so many chronic conditions are related to “leaky gut’ syndrome.

        • KristenM says

          Brine or salt-cured foods are also lacto-fermented. The brine or salt is just preventing unwanted bacteria from taking hold and spoiling the ferment before the lacto-bacilli culture can take hold and outcompete any unwanted bacteria.

          These ferments *are* full of probiotics. The way you can tell is that your end result is acidic thanks to all the lactic-acid the lacto-bacilli culture created. If you don’t trust your taste buds, just get some pH strips to test it.

          Mason jars truly are a safe way to ferment. If you want to create an anaerobic environment in a mason jar, you can put a layer of oil across the top of the ferment. It’s not complicated or expensive.

          I really appreciate what Pickl-It and Harsch crocks do. I love the way they help keep ferments consistent, prevent mold and other unwanted bacterial life from forming, etc.

          My concern when I wrote this post is that so many of my readers wrote to me asking if they should *STOP* fermenting altogether because they couldn’t afford to “do it right.” There are many right ways to ferment! Some are better for certain goals than others. (Hence, me including Wardeh’s wonderful answer of there being good-better-best methods.)

          But to say that mason jars aren’t safe is simply not true. They may not be *your* ideal method, but you could still ferment with them using a little oil on top and have a wonderfully probiotic-rich result ideal for people using ferments therapeutically and zero concern about mold, aerobic fermentation, etc.

    • Lisa says

      Hi Lisa
      I am new to all of this and am soaking up the information. I am interested in your post and would like more information to see why you say this. Why are mason jars not necessarily safe/good for your health? What does biochemistry tell us about this? What is the full story? I am very interested to read how chemistry has proven that raw milk is safe for us? How are we protected from harmful bacteria such as Brucella, Campylobacter, Listeria, Mycobacterium bovis, Salmonella, Shiga toxin-producing E. coli, Shigella, Streptococcus pyogenes, and Yersinia enterocolitica?



  24. says

    Great informative article, Kristen! Thanks for covering this topic and getting input from the experts. I also enjoyed your previous article about the use of Kickstarter as an option for farms to finance various projects. I mentioned it to the owner of the small farm where I buy my raw milk, eggs, meats and other produce, since they acquired more acreage and are expanding their operation. I’m always learning something from your posts, which are very helpful for those of seeking to eat real, nourishing food!

  25. olivia says

    Thanks for the explanation. My problem is I struggle to keep the ingredients under the brine. I try to find glass ‘discs’ to lay of top but it’s difficult to get the right size and even then I get pieces around the edges floating up. It is so frustrating that I have given up on ferments. Can anyone help me with this? I really want to do ferments again but I’ve had too many spoil.

    • KristenM says

      Have you read through the comments? A couple posters shared their methods for keeping veggies submerged. I’ve used a shot glass with a large leaf (like a grape leaf or cabbage leaf) before. I’ve also just added brine (it’s just salt water, after all). Both methods worked well.

    • Jeanmarie says

      Olivia, I used to struggle with this, too. If you don’t find the right size plate to place on top of your ferments, you can use cabbage leaves, or a ziploc bag filled with brine, so that even if it leaks, it is only leaking brine. Or just add more brine. It’s also helpful to pound your cabbage so it’s more compact and more water comes out of it. It seems to float less then. Keep trying, and you’ll get the hang of it!

    • olivia says

      Thanks. I’ll try again with added brine. I’ve tried putting cabbage leaf on top but even that floats up with time even if initially all submerged some stuff floats up.

      • KristenM says

        That’s why you have to weigh the cabbage leaf down with something like a cup, a stone, or a shot glass.

    • says

      To keep my vegetables submerged, I use a 1/4 cup canning jar sold for canning jams and jellies. It does take a little space in the jar, but when you screw the lid on, it pushes the vegetable down into the brine. I usually have to add a little more veg to make the brine come up near the top. I’ve never had any mold when I used this method. I put the jar in right-side-up. – Judy

  26. olivia says

    Just to add to my above comment. When I make sauerkraut so many air pockets form inside between the cabbage. Is this a problem?

    • KristenM says

      Yes. If I were you, I’d add enough brine (salt water) to cover the veggies by about an inch while still leaving about an inch of room at the top of the jar to allow for CO2 expansion.

          • Jen says

            Perhaps the air pockets Olivia is referring to is the formation of gas bubbles as a result of lactic acid bacteria growing? I never have air pockets at first, but after a day or so, bubbles form down in the cabbage, and eventually float up to the top. I always assumed this was perfectly normal, as gas does form, and need to escape during fermentation. It relates to the whole “fizzy” thing, right?

            • KristenM says

              Well, THOSE air pockets are fine. Just escaping CO2. I’m talking about air pockets when you pack your kraut down to begin the ferment. You don’t want any of those.

              • Jen says

                I know, Kristen. :) I was just suggesting that maybe Olivia has escaping CO2 bubbles, and doesn’t realize that’s what it is. Maybe she is mistakenly describing them as “air pockets”. If so, then she obviously doesn’t need to worry about it.

                • olivia says

                  Thanks for clearing that up. Yes I was mistakenly calling them air pockets but they are part of the fermentation process. But last time I tried it, so much CO2 built up that the cabbage hardly looked as if it had enough brine in it even though initially it was completely covered with a thick layer of brine. Oh well, I’ll just try it again.

  27. says

    LOVE, LOVE, LOVE this post, Kristen. Thanks for writing this post and gathering all these experts to share their experience and wisdom with us! This is a post that ever real foodie should read! Blessings, Kelly

  28. says

    Ahh, thank you! I have been curious about all the controversy over this issue. It hasn’t made any sense to me to suddenly be concerned about a method that have been proven effective for generations upon generations. Thanks for putting all the thoughts together in one place.

  29. Melanie says

    I love Wardeh’s explanation of good, better and best and that’s how I’ve been answering this question as well.
    I’ve been fermenting for years with only one batch ever going off but because of what I’ve been learning (from microbiologists and scientists) has made me change how I ferment. Not so much because I’m worried about a bad batch but because I want to get the best out of my food and experience the most healing possible.
    Now I only use Pickl-It jars and I’m experimenting with my first batch of sauerkraut with a layer of oil (blogging about that tomorrow).
    I do wish you had linked to KerryAnn’s posts so people could read for themselves what the ruckus is all about. I’m hoping that by this info getting out there people who have hit a wall in their healing can find further healing by fermenting the right way.

  30. Angelina says

    Thank you for posting this!! I just had my first batch of cultured jalapenos go bad (really bad!) and it left me confused. I actually had two jars grow white bubbly disgusting mold on top (two jars at once!) and the smell and flavor was too much to bear. They were dumped and I was left trying to figure out where I went wrong. I then heard about the Pickl-It jars, which sounded interesting, but I simply couldn’t afford them right now. So I was about to give up fermenting for a season. I am so glad that I can go back and do it safely! I may try the coconut oil layer but either way, I will not worry. God bless you! :)

  31. says

    Thank you so much for this post. I am a nutrition educator who runs a GAPS group with a local pediatrician and I have been fielding questions since this whole controversy started. My answer has been the same as yours and Sandor Katz’, and I am thrilled to have this as another resource for the group. When I teach fermentation I do show Pikl-it’s and talk about crocks, but many folks just can’t afford them, or aren’t sure they want to invest that way in fermenting vessels. I am dissing these tools at all, but acknowledging that wonderful fermentation can and does occur in other vessels. Gee, my forbears made kraut and pickles in barrels–those can’t be completely anerobic ferments, can they?

    • Lizzie says

      The way my grandma from Alsace taught my dad to do Kraut is the way he taught me. If you come from a kraut culture, you know it’s a cool-to-cold climate. My dad taught me that you need to use a crock and BURY it for at least a month. The EARTH around, on top of the crock made for an anaerobic environment…
      As someone who did aerobic mason jar cow’s milk, coconut milk, and coconut water kefir and got sick all three times, let me tell you as honestly as I can that it is taking me a long time to recover. I had trusted various food websites to be “scientific” but I got sick even from kefir that was handled correctly according to the food “expert” blogger. My son is a chef, and he said, you know Mom, that’s gonna get you really sick…
      Mom is not always right. My dad was right, my son was right. The interwebs foodies, uuuh,not so sure… I’m much happier, healing, with my new tiny investment in the pickl it. It’s cheaper than the ER visit was…

  32. Terry says

    No matter the diameter of the vessel wood disks can be cut/made for compression plates. Hardwoods please, conifers create issues with their tarish saps, but people still use them. Did you catch that Sandor uses them in his Kraut Crock? They work great in my pickle barrels too. After the first use they also become “carriers” for our little fermenting wonders.
    One more thing, a block of active dry ice in a small cooler provides enough co2 to displace room air. Just let it fog up a little, put your jar on the floor of the cooler, wait a sec, reach in and cap the jar, pull it out and you have a sealed container full of your ferment and co2.
    The dry ice thing works great for fast freezing fruits,vegi’s and the like also. Layer them on paper or baking sheets(make sure the co2 can flow around),insulate from your dry ice,cover and they freeze- fast.

      • Terry says

        ANY time, maam. I’m a foodie from the fifties. My Father the best natural cook I’ve ever known, my eldest brother an internationally recognized registered chef(degree from University of Nebraska), my brother-in-law a Korean double Dr., my Gma a wiry old woman who put up more lacto-ferments per year than the combined weight of your local highschool football team.
        I think I’ve been a fan of Sandor’s since the first time “Mother Earth” or somebody like that stole one of his articles and published it. Ouch. Age thing.
        Anyway, if you feel the need for backup, feel free to consider us your “A-team”. I love to contribute.

  33. says

    If you would like to try PicklIt containers but find them too expensive, see if there’s a brewing store in your area. I found air locks for $1.25 and grommets for 50 cents. I drilled a hole in a plastic lid for a large glass jar, popped in the grommet and air lock, and voila…half-gallon Pickl-It for $1.75. The brine never touches the plastic, so I’m not worried about that.

  34. Michelle says

    I made my first batch of saurkraut last week and I tried to block air by a ziplock filled with water. It never really created a seal and the saurkraut didn’t taste very good after it was done. I was afraid it was because of the oxygen getting to the kraut, but now you have relieved my fears! I am so thankful to have read this article. It was incredibly helpful!!!! :-) Perhaps I just need to let it sit longer so that it will taste better?

    • KristenM says

      I honestly *hate* the taste of homemade sauerkraut unless it’s been fermenting for at least 3 months. 6 months is my ideal.

  35. says

    Thank you so much for compiling this info. I am new to fermenting and have to say, I buy into the fear that the “man” wants me to feel. I even felt a little weird leaving dill pickles in my pantry when I ran out of room in my fridge. I’m totally rethinking everything and those opened pickles are still fine in my pantry. Thanks again!

  36. Jeanmarie says

    For those who want a cheaper and easier alternative to either Pickl-It or drilling holes and tracking down parts from a brewing shop, Cultures for Health sells a plastic lid that fits a mason jar and has an airlock in it. I forget the price but it’s very reasonable and works well if you’re not confident about keeping air out of your ferments.

    • says

      This looks like a GREAT set-up. I see no reason why this wouldn’t work as good as a Pickl-It. I plan on having it in my line-up for testing in a couple of weeks.

  37. Jen says

    I find it “interesting” that all three sources you consulted are all of the same “belief” system, where’s the science links? I’d like you to show some science, and not just opinions.

      • says

        Microbialogically speaking, “anaerobic” means something that can live without oxygen.

        I think what was meant to be said was, “if the ferment is submerged, it’s not exposed to air.” This is true.

        However, when you simply have cheesecloth draped on the top, the brine itself is exposed to the air. This allows the oxygen-loving bacteria, yeasts, and molds to have the upper hand and grow.

        Sauerkraut likes to be suffocated! :)

        I didn’t know all this until researching. I posted the link to the article, The Science of Sauerkraut Fermentation, further down in the comments.

  38. Adrian Dent says

    The only issue I can see with mould growing on a ferment is that if it deelops early in the process, it may kill the good bacteria (as penicillin would) before they can do their job.
    And as for the comment “If you eat cheese, you are eating mould.” this is only true of the yummy cheeses such as the various bluevein (penicillium roquefortii) white crust (penicillium camambertii) and red mould cheeses. Most of the other cheeses are just ferments, i.e. bacterially formed.

  39. pd says

    I too am a fan of traditional fermentation. *And*I would love to see a simple test of 3 different methods of fermentation repeated in different parts of the country, with results in acidity and number of bacteria and sm what kind of bacteria. Just so we know how much is different.

  40. HeatherT says

    Kudos to you and thanks! I’m all in favor of experimentation, but it should not require expensive equipment to make a “proper” ferment.

  41. Kim says

    This was an interesting read. Every summer as a kid we would make crock pickles and the crock would live in the basement all summer long until the pickles were gone. I am hoping to invest in a crock of my own soon to make some of the delicious pickles!!

  42. says

    Thanks for this post Kristen.

    The Pickl-it may be a great product, but I do not believe that it is the only way to go. We, at Cooking God’s Way, have taught Lacto-fermentation in our classes for years now using the Air-lock System we created. The reason we designed the system was so that everyone could afford an anaerobic fermentation system no matter their budget. Yes the system uses mason jars, an air-lock, and a specially designed food safe natural rubber gasket to keep it air-tight.

    I’ve been so saddened by this whole mason jar fermentation controversy. Lacto-fermented foods provide such great health benefits…I do not want to see others scared away from fermenting due to all this and I am concerned that is what is happening. We as “real foodies” should all be standing together in this as a community, not fighting each other.

    • Laura says

      I read your post with interest. I’ve been jar fermenting for a couple of years with so so results.
      Looking forward to your experiments. I’ll be doing mine (with my new pickl-it jar) at the same time. I still think Mason jars are ok, but like everything in cooking I find the need to upgrade my knowledge, my skills and my equipment periodically.

      PS I really want to say that I don’t feel that pickl-it is making this controversy to make a profit. Like any small maker of a product and small micro business, they are just showing us a great modern way of replicating the “air-lock method of fermentation. How smart is that? I’m impressed by Kathleen and her company.

  43. says

    Thank you so much for writing and putting this blog post together. I love what you are saying, and share it all the time with my clients. Great information.
    Mathewsons cultures for life

  44. David Pajerowski says

    Hi All,

    I’m a bit worried by the obsession with requirement or desirability of supposedly “anaerobic” fermentations, particularly as the most dangerous conditions possible for a fermentation, the growth of clostridium botulinum bacteria (think botulism), can occur only under completely anaerobic conditions.
    Pay close attention to the distinction between facultative and obligate anaerobes on the one hand … lactobacilli can grow both in the absence and presence of oyxgen (facultative anerobe), while c. boltulinum can’t grow at all in the presence of oyxgen. Maintaining some oxygen in the ferment is great insurance against killing yourself and your family/friends with butulinum toxin.
    It is true, as some have commented, that the liquid and air above are in constant equilibrium with respect to oxygen … there may be areas within your ferment (the bottom for example) that have the lowest oxygen levels, but with the top open to the air, there will be a constant flux of oxygen into the ferment, as the microbes consume the oxygen in the water.
    in practice, your ferments may be “micro-aerobic”, meaning there is some oyxgen, but not enough to support microorganisms requiring high oxygen concentrations. I think this is probably the safest regime to operate in.
    Keep the tops under water, so that the molds dont have organic material to grow on up where there is lots of oxygen, and you should be good to go.

    Hope this helps a litle,

    • Liz J says

      The acidity created by the lactobacilli kills the botulinum. Now this oil method, however, could certainly harbor botulism…

  45. Karen says

    This is about rusting lids, and weighing down the corn in the jar–how I am dealing with it:
    This is about “pickled corn” (without the vinegar.)
    I must admit that I have not read ALL the comments here, so please forgive me if this have already been addressed.
    This is my FIRST year doing this.
    I bought half-gallon wide-mouthed mason jars. Washed and sterilized them in boiling water, along with their lids.
    Added the chunks of whole ears of clean, blanched corn (broken in half or in thirds,) the pickling salt and the water (I have good well water–no chlorine).
    Then placed the lid and ring on the top LOOSELY–with my intent being to replicate the environment of the pickling in a crock like our grandparents did (fermenting) because I did not have a crock.
    It has been almost FOUR weeks now, and I keep checking the jars, and they seem to be doing well–on one jar only a little white (mother) is growing. They smell slightly sour.

    Even though the brine was covering all the corn, I still felt like I should weight them.
    Today I read about someone using BOTTLES for weight.
    Whaala! I got out my little glass jars–like old maraschino cherry jars, etc., and bleached and rinsed them really well, and slipped them in the top of the jar, therefore pushing a little of the brine out into the sink.
    I cut a flour sack towel into a square, and put in over the top, held in place by a rubberband, and now I am SO happy that I do not have a rusting lid or ring on top, AND am “pickling” in a mason jar / substituted for a crock!!!!
    Hope this helps somebody.
    Thank you guys for your tips that helped me!!

  46. broccoli rob says

    When I top off my pickles with oil in a mason jar, do I put the cap on the jar? Or do I just leave it uncovered?

  47. broccoli rob says

    Sorry, I was just wondering because if the oil is covering it should I leave the lid off so it can release gas? Eventually I will cap it once it goes into the fridge…

  48. Liz J says

    Isn’t anyone concerened with oil and botulism? I though when oil was in contact with substances that can feed bacteria, it creates the perfect storm. The oil creates an anaerobic layer that is not acidic enough to kill botulism. Please correct me if I’m wrong.

    I think people really need to read Kerry Ann’s posts mentioned above, regardless of her reactions here if they want to get a more deeply detailed explanation of each issue addressed here. I love that this post brings us down to reality about safety, and I agree with the safety of open ferments. I just think it’s wise to take advantage of the whole truth so we can each experiment with more knowledge.

    Kerry Ann explains how bacteria that don’t like air go as far as possible from it, therefore the lactobacilli are at the bottom of the jar. Every time you dip in from the top layer you’re not getting as many LAB’s as you would with airlocked system. My take- good better best, but why waste time and not get the best results when it only costs a few dollars to make your own system that very well could work just fine.

    Some people just don’t heal until they switch to airlock. You can read about that in Kerry Ann’s posts. Her own story is quite compelling.

    In fact, I have had a strange rash after coming back from vacation and reconstituting my milk kefir grains, and it’s lasted a year. It is possible that candida or other things I don’t want in there are infultrated. I wouldn’t call that dangerous, and all of the “experts” I have asked have said it is absolutely possible to get candida etc, in your grains, starters etc. but that eventually a healthy starter should balance itself out. BUT, with someone like me who has 35 food sensetivities, It’s just silly to do all this work and not do everything I can to get more of what I want and less of what I don’t.

    I’ve ordererd what I need to make airlocks I am confident will work, for about $1.50. I’ll let you know what I discover. I’m hoping Kerry Ann is being overly cautious with her insistance on the Harsch sp? crock or Pickle It. There’s truth to both sides… keep it simple, but don’t get complacent if you want better results.

    • Liz J says

      ok so here’s my update…since using my cheapo homemade airlocks with tattler lids, airlocks and grommets from a brewery store, the strange rash is gone. It could be coincidence, but that would be very surprizing since it stuck around on my elbow for a year. I made about 5 of them for just a few dollars a piece. I’ll still do plain ol’ jar ferments without airlock from time to time, but I think to ensure more good guys in the majority of my ferments is helpful.

    • Sarah says

      What are these bacteria that are so afraid of oxygen that they would bury themselves at the bottom of the jar to avoid it? Let’s not forget where the microbes come from that do the fermenting – they come from the vegetables themselves, which are grown in sunshine and fresh air, or aerated soil.

  49. Mikey says

    Somewhere in the cosmos, our anscetors are laughing-to-tears. Pickl-its, mason jars, harsch crocks, etc…etc… The “Healthy Living” movement has gone bonkers. It has been invaded by keyboard commandos in the blogosphere.

    Oh, by the way; I love ferments. Aerobics, anaerobics, I love them all….

    Nice to meet you all.

  50. Don says

    Is it okay to top off the jar of kimchi with just water Instead of the brine solution to act as an anaerobic barrier. As the brine solution is very salty To taste, and I’m concerned it’ll make the kimchi too salty.

    By the way I made kimchi in the past That I allowed to ferment for several days Which wasn’t submerged in
    liquid; as I wasn’t familiar with this practice so the cabbage leaves were merely coated with the paste and a small amount of liquid in the bottom of the jar. I am Not sure what the level of good bacteria was But the stuff taste awesome to everyone. Now I’m trying to maximize good bacteria And it seems invariably I end up with more questions as I go…

    Thank you so much for this blog it’s awesome so are you all.

  51. Morwalk says

    This is a really informative piece. I am new to fermenting and just finished eating my first batch. I followed a simple recipe I found online and just put a bunch of things into previously-used, but clean, mason jars and previously used lids (I now know I’m not supposed to reuse lids). I just put a bunch of stuff into the jar, peppers, cabbage, cucumbers, garlic, ginger, pepper corns. Surprisingly, the two jars I made turned out great! The result was delicious! It made for an easy salad to just throw some of those veggies onto some spinach and mix it all up.

  52. Shellee says

    What lid method do you use? I am using mason jars with white plastic lid with whole and rubber grommet, along with a airlock (got from home brew store) I get intimidated by this though. I made dilly carrots again…use dill seeds..this time there was white mold at the bottom. Wondering if my salt did not mix well.

    Another thing I have pondered on. Is in the days of no fridges..How did they store their fermented foods without them going bad while they are eating them? Because once you open them they can go bad?!

  53. says

    Wow. Thank you so much for posting this!! I’ve been concerned about whether home fermentation in mason jars is safe and now feel much better! I just made some lacto-fermented pickles and Moroccan lemons. I can’t wait to pickle even more stuff!

  54. Mary Hagerman says

    Hello, I’m new to fermenting and have purchased a few air-lock units, but they are pricey. I haven’t tried the Mason Jar process but will give it a try. If air causes a problem, I was wondering if after preparing the jar, I could place it in a food saver bag and vacuum seal for another layer of protection. I haven’t read all the comments so I’m not sure if this has been tried before. Has anyone tried this?

    • Alan says

      I myself am looking for the safest way to store sauerkraut. However, from everything I’ve read it’s not a good idea to store sauerkraut in direct contact with plastic as the acids will leach chemicals out of the plastic there by negating the healthy benefits.

  55. Sarah Ferguson says

    Ahhhhh….this is SUCH a refreshing post! Thanks food renegade, I totally trust the judgement of Sandor Katz & Sally F. Morrell way more than the pikl-it ppl (although I do think it’s a convenient idea) – but i like the traditional way of doing things myself :-) Thanks again!

  56. Wendy C says

    Thank you for this. I’ve been wanting to get into canning with a pressure cooker. I will look up that first book you mentioned :)

    I have been using a ‘vacuum seal’ for my jars for a few months. I’ve used it for broth to freeze, my flours and anything else that I will store for more than a week.

    I found out about it from Paula at Salad in a Jar – here is her link:

  57. Nancy says

    Hello fellow picklers .. I am new to culturing vegetables, in fact I literally just finished putting together my first batch (diced beetroot). I am concerned because I did not add brine along the way, rather I waited until my vegetables had reached the top of the jar and then added whey and brine to submerge it all underneath some green leaves. As a result of waiting until the jar was already full, I can now see several small air pockets in my jar and despite giving it a bit of a shake-around, the pockets are still there. What should I do assuming one of you notices my post in the next say 24-48 hours and replies? Should I leave it as is and hope for the best or will it be too late to remove the contents and re-pack it all so that there are no air pockets? Any answers to this would be very much appreciated and hopefully either way my first batch won’t fail and scare me off trying again. Thanks very much for your help.

  58. KJ says

    Well, this article is so sensible and informative that now I am going to follow your blog! You answered my question….what did people DO before all these new fermenting contraptions? I love the cabbage leaf/stone method (I mean who doesn’t love the idea of using a stone in cooking? Really.), but had never run across a layer of oil on top…love that and will try. You made me happy today.

  59. says

    I’m confused. In this post, “” you say that the mold is bad and you don’t want even a little bit in your ferment. Then in this post you say it’s fine. Which one is true?

  60. Marcy Jackson says

    As one who now only ferments in glass anaerobic vessels; not only to avoid mould contamination but also the production of histamines (a real problem with fermented foods), I find it interesting that Jenny, Sandor and Wardeh have all use PIckl-it jars for some ferments (if they are useless, as this article seems to suggest, then why would these seasoned fermenters even bother with them). Mr. Katz also uses oak barrels in a dark cold cellar, which is much different then on-counter, exposed to light, mason jars.
    The way I see it, Pickl-it is not an overpriced mason jar, rather it is inexpensive home fermenting equipment that produces the best quality ferments I have ever tasted…and I have done over a decade of fermenting (using various methods). I simply would not go back to the mushy, mouldy, cheesy tasting mason jar ferments after tasting the difference from my Pickl-It ferments (no whey required). Trust me, it is worth the investment. Best of all, the ferments last extremely well from harvest to harvest and are delish! I have never had to scrape mould from a Pickl-It…ever!
    Happy fermenting everyone!

  61. Lindsey says

    I really like that you took the time to seek out thoughts from the experts. There are so many theories floating out there about so many things, and most people don’t bother to really give controversies due consideration! I threw out my first couple of sauerkraut attempts (several years ago now!) because the mold disturbed me. Then I heard Sandor Katz’s view on things and I was able to finally, permanently, put the fears to bed. It’s a great feeling to come to terms with something like fermentation – it used to feel so mysterious and the scariest word – “botulism” – was always hanging in the air for me, whether logical or not!

  62. robin says

    Just finished making my first batch of sauerkraut in mason jars with plastic lids, then I found this website. Sandor Katz stated “mason jars become highly pressurized and if you fail to loosen them to release the pressure.” My questions are, do you tighten the tops and then release them once a day or how often does this need to be done?
    If I pour coconut oil over the top will this effect the pressure?

  63. Allan Moss says

    Very interesting. I am new to home fermenting, but have done about 40 quarts of various things over the last year, in jars, without difficulty or problems. I recently came across this question, so I decided to look into it myself. I am not a scientist, but do have a BS in Biology and more than a few graduate level science courses under my belt. While lactobacillus are not the only lactic acid fermenters out there, they are by far the most prevalent in fermented foods. They are not, however, strict anaerobes. Lactobacillus are what are classified as facultative anaerobes: the fermentation process (rather than respiration) persistent within the cell is anaerobic, yet the bacteria can thrive in even oxygen rich environments. Some of the probiotic lactobacillus (acidophilus, fermentum, reuteri) have been studied and found to be just as effective fermenters in low oxygen environments as completely anaerobic environments. In regards to the question of traditional ferments, my understanding is that more airtight vessels sustain longer ferments, such as stone jars, sealed with clay and buried (kimchi – many months), or wax-sealed amphoras weighted down in water (anchovies – years). I have been open fermenting pickles and sauerkraut without ill effect or mold. I am very very careful about salinity, measured at 4% salt (by mass on a digital balance). This retards the growth of molds while sustaining lactobacillus. A higher salinity will begin to retard the fermenters. Another important note is that Botulinum are a true anaerobe; low-oxygen enviros (as opposed to oxygen-free) actually retard growth and toxin production in botulinum, whereas an anaerobic environment favors it. I’d rather have a little visible mold (a sign to discard the ferment) than invisible botulism. Good luck!

  64. Phil says

    I like the less expensive way of fermenting with mason jars. I’m just concerned that the metal lids will give an “Off-taste” to the finished product. Do you use plastic lids and if so, where can you buy the plastic lids.

  65. H J says

    This is an interesting post that got at a lot of questions I had regarding fermenting without an airtight seal. I wanted to note, however, that the argument about CO2 forming a barrier layer is not correct, in my opinion. Although CO2 is a heavier molecule than O2, gravity is not the only force acting on air molecules. There are entropic and thermal contributions as well — both of which are far stronger than gravity in this scenario, and which favor the mixing of O2 and CO2. Thus, I would be hardpressed to believe that CO2 acts as a barrier layer in the way that you have stated.

  66. Marc Katelyn Saradjian via Facebook says

    I never had a mason jar ferment go bad in process until I tried a pickle-it. Needless to say, I tossed it and have used straight up mason jars since.

  67. Sarah L. Peterson via Facebook says

    I made sauerkraut like this according to Nourishing Traditions and used the correct amount of salt it said and it’s sooooooo salty. Good crunch, just too salty! What did I do wrong?

  68. Jessica Swafford via Facebook says

    Great article – I read the whole thing and loved it even though I didn’t know there was a mason jar controversy.

  69. Tamy Kasdorf via Facebook says

    Thanks!! I never knew about topping with oil… I use mason jars… its all I can afford right now…

  70. Susann Laverie via Facebook says

    Good article, but your site is almost impossible to read. Between the very fine font you’re using which is very light and the gray color of the text, I couldn’t read the majority of what you wrote and i had the point size up to 175. I love your articles. Pls print black on white so they are easier to read.

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