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.

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. 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.

CLICK HERE TO DOWNOAD 7 PROBIOTIC RECIPES YOUR KIDS 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.