We all want our refrigerated food to be safe to eat. That’s why we go through the fridge on a regular basis and follow the rule, “When in doubt, toss it out.” But unlike most foods we keep in the fridge, our wildbrine probiotic fermented foods come ready-colonized by health-giving bacteria. So, what’s the story with these foods? How long does sauerkraut or kimchi last, once the jar is opened?
How Long Does Sauerkraut Last?
Here’s some good news: sauerkraut and kimchi can last in the fridge for a month or two past the expiration date that’s printed on the package—If you understand what’s going on and what keeps these foods safe and tasty.
Your wildbrine sauerkraut or kimchi is fermented rather than salt cured. That means the vegetables were kept submerged in a weak brine solution of between 2 to 5 percent salt, depending on which vegetables were fermented. At first, the vegetables carried into the fermentation vessel any microorganisms that were on their surfaces, including spoilage organisms as well as beneficial Lactobacillus acidophilus and other acid-loving bacteria (often referred to as LAB—lactic acid bacteria).
During fermentation, the LABs went to work on the sugars and carbohydrates in the vegetables, turning them into lactic acid. As the weak brine became more and more acidic, the spoilage organisms were killed off. The vegetables developed the lip-smacking sour flavors that make ferments so delicious. After all, the word “sauerkraut” is German for “sour herb.” By the end of the initial fermentation, the LABs rendered the vegetables tastier, more nutritious, perfectly safe to eat, and probiotic, meaning the bacteria that fermented the vegetables could now take up residence in your digestive system and continue to provide health benefits and improved nutrition as they participate in your gut microbiome.
Incidentally, salt curing is done with a stronger brine—from 10 to 20 percent salt or more. That amount of salt will preserve the vegetables, but is too salty to allow the LABs to grow, so salt-cured foods are not fermented.
So, what’s this mean for our question: how long does sauerkraut or kimchi last once the jar is opened? And the answer is a couple of months or even more if three requirements are met.
First, the vegetables must remain submerged a 1/2 inch or so beneath the brine in the jar. If they float to the top and are exposed to air, they will eventually become moldy and inedible and the jar will be spoiled. If there’s not enough brine in the jar to cover the vegetables, add a little filtered water, enough to fill to above the vegetables. To keep the vegetables submerged, weigh them down with a small plate, cup, or freezer baggy filled with weak brine.
Second, the sauerkraut and kimchi must be kept refrigerated at all times. If you want to serve some with a meal, transfer the meal’s worth to a cup or bowl and put the jar of kraut or kimchi back in the fridge without letting it sit out and warm up.
Third, only use a clean utensil to take the fermented vegetables from the jar. Don’t eat from the jar by reinserting the utensil in the food. If you double dip, you’ll be seeding the food with a wide range of mouth and other bacteria, and it will eventually spoil.
Over its time in the fridge, sauerkraut and kimchi will become more acidic as the LABs proliferate, the crunchiness of a fresh jar’s vegetables may abate and become softer over time. But as long as you keep the vegetables submerged and enjoy the flavors, you’re good to go.
About the Author: Sonoma County resident Jeff Cox is the author of 24 books, including The Essential Book of Fermentation (Avery, 2013)