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.
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.
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.
(sauerkraut photo by johnnystiletto)