When Fermentation Goes Wrong

Use these tips and tricks to help your sauerkraut and other ferments from becoming soft, moldy or otherwise undesirable.

by Amy Grisak
PHOTO: Susy Morris/Flickr

There’s nothing like making your own tasty and nutritious ferments at home, but because you’re not dealing with wild cultures—not a controlled, cookie-cutter process—sometimes these projects go awry. Sauerkraut can turn mushy, pickles look funky or there’s an unsettling fuzz covering the brine. A lot of people find themselves asking, “What did I do wrong?”

The good news is you’re most likely not creating a deadly concoction in your kitchen.

“There is no recorded case of food poisoning from fermented vegetables,” says Sandor Katz, the Pied Piper of all things fermented and author of The Art of Fermentation (Chelsea Green Publishing, 2012). “You don’t have to be afraid to taste it.”

Yet, for those of us with less experience, staring into a bucket of vegetables that doesn’t quite look like the photos we saw online or in a book makes us wonder what went wrong and what can be done to correct it. Here are some common fermentation mistakes you might run into and how you can prevent them.

Bloated Cucumbers

Eric Hurlock of Pennsylvania has been fermenting vegetables for three years and has experienced a few puzzling ferments. One of them included fermented cucumber pickles that turned out hollow and mushy.

“I put in some oak leaves for the tannins, plus some dill and maybe some onion,” he says. “I’ve done it before, and they came out fine, but after a week these were super mushy and completely hollow.”

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A bloating occurs due to too much carbon-dioxide build-up in the cucumber. On a positive note, Katz says it’s not dangerous to eat—it’s just not desirable. The addition of a high-tannin ingredient, like oak leaves, grape leaves or horseradish, can help slow the fermentation process and keep the cucumbers crisp. What you use depends on availability and what you prefer for taste.

With fermenting there are a number of variables that affect the process, including heat, the amount of salt (if any) and time, and rarely do two ferments turn out exactly the same. Because cucumbers are typically ripe at the height of the summer heat, Katz notes that this could also be a contributing factor to the firmness of the cucumber ferment. Using smaller, pickling cucumbers can help achieve a more appetizing final product.

Soft Sauerkraut

Because sauerkraut is one of the most popular ferments, particular by those fermenting for the first time, it’s one that raises a lot of questions.

Cabbage is often a successful vegetable ferment because it’s typically ripe in the fall when the temperatures are cooler and fermentation can occur more slowly, though this isn’t always the case. If you’re making sauerkraut in the summer with a spring cabbage, the heat of your environment can lead to a softer end product. To combat this, keep the bucket or crock holding the fermenting cabbage in a cool area instead of on your kitchen counter in 90-degree-F heat.

“You can’t leave it out for weeks or it will turn into baby food,” Katz says. It’s still edible, but not many people will enjoy it at this stage.

This also raises the question of the amount of salt that should be used. The primary reason for salt is to help pull moisture out of the vegetables and to slow down the fermentation process. You can use pretty much any salt that doesn’t have iodine or other additives, though some people shy away from the chunky salts because they don’t dissolve as well. Katz says our grandparents and great-grandparents had to store a winter’s worth of vegetables by fermenting them, so they had to use enough salt to keep the vegetables from being completely soft by spring. But for us, it’s more a matter of taste.

“You don’t have to make it extremely salty,” he notes. “People’s palettes are varied to what tastes good.”

Add enough salt to make your ferment flavorful, but if your vegetables are breaking down too quickly, add a little more to slow it down or cut down your ferment time.

Moldy Carrots

Another issue you might come across in your ferments is mold. Hurlock has experienced this with his fermented carrots, which turned a blue-ish hue, so he tossed out the entire batch. The mold could have occurred, he says, because the carrots weren’t submerged all the way under the brine.

If you’ve found mold growing in one of your ferments, you’re not alone. Molds happen, Katz says.

“Most types of surface molds are white,” he notes. “But there are definitely molds that can be very toxic.”

If you find a white mold on the surface, he recommends skimming it off and throwing away any affected vegetables. However, if you come across any other colored molds, like blue or orange, use caution and destroy the batch.

Having the carrots exposed to air instead of being submerged was probably the vector needed to produce the blue mold. Plus, a shorter fermentation time could be appropriate for vegetables, like carrots, that have higher sugar content, Katz says. Adding spices also often inhibits mold growth, in addition to providing exceptional flavors.

Fruit Fly Nesting Site

Kombucha is a delicious beverage made by fermenting sweet green tea using a SCOBY (symbiotic culture of bacteria and yeast). During the first ferment, the tea takes on a vinegar-like flavor the longer it sits out, and then the liquid is placed into an airtight container with fresh fruit or fruit juice during the second ferment to create a bubbly and tasty drink. As with any ferment, though, there are factors that can compromise the final product.

One risk with kombucha, particularly during the summer months, is the presence of fruit flies, which can lay eggs in the SCOBY. If you see small worm-like creatures growing in your kombucha, throw out the SCOBY and find a fresh one. Kombucha and other ferments can be protected from fruit flies by securing a cloth over the container with a rubber band.

With more people delving into home fermentation, there are bound to be blunders along the way. The good news is everyone has made them. Follow the simple guidelines of using salt to your taste, keeping your vegetables under the brine, and providing the proper temperature and adequate time, and you can avoid a few common mistakes and enjoy your healthy vegetables in a new and delicious way.

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