FAQs
In this section, I answer some of your most frequent questions about fermentation.
What is the best temperature to ferment at?
The ideal fermentation temperature for producing sauerkraut with the most complex flavors is between 65 and 70°F (18–21°C). Ideally, you want the temperature to be somewhat stable, not fluctuating more than 5°F (3°C) in either direction.
If you live in a warm climate, many are able to create a cooler space using an ice chest with frozen jugs of water. See 11 Cool Fermentation Tips for Hot Weather for further details.
Is my home-fermented sauerkraut safe to eat?
Yes. Very.
During fermentation, the bacteria eat the sugars in the vegetables and cabbage and make lactic acid, the vinegar-like tang you taste when you eat fermented vegetables. As this happens, the pH of your jar of sauerkraut is lowered to a range at which harmful bacteria cannot survive. The result is a safe, preserved, ready-to-eat ferment containing trillions of beneficial bacteria.
As long as the color of your cabbage has faded from bright to dull green, there are no noxious, knock-your-socks-off odors (you’ll know), and it tastes tangy (somewhat like vinegar), it is perfectly safe to eat.
How do I protect my sauerkraut from mold?
Mold grows from mold spores everywhere in the air and begins growing when they land on a wet surface with nutrients (such as your bits floating on the surface of your ferment). They can actually survive in acidic foods, so it’s not necessarily the acidity that deters them.
To reduce the chances of mold growing on your sauerkraut, keep it under the brine, use the right amount of salt, and ferment at ideal temperatures. Here are some ideas for how to keep your ferment below the brine:
3 Key Items for Keeping Your Ferments Safe [BELOW THE BRINE]
Why is my sauerkraut dry?
You can end up with a batch of dry sauerkraut for many reasons, the most common ones being fermenting with old cabbage, not including moisture-rich vegetables in your sauerkraut, and fermenting in the smaller environment of a jar (a good way to learn) vs. a large crock.
I have a complete post devoted to this—Dry Sauerkraut? 17 Transformative Tips—with many more tips and suggestions. Here are a few:
Use fresh cabbage. Even though cabbage is approximately 92% water, if it is June and you’re about to make a batch of sauerkraut, that cabbage has most likely been in cold storage for six months and will have lost much of its moisture.
Loss of moisture means less brine. The closer to harvest that you purchase your cabbage—and make sauerkraut—the more brine it will produce and the less chance there is of dry sauerkraut.
Add moisture-rich vegetables. The carrots in this recipe add valuable moisture—and flavor. When packing your jar, if you don’t have enough brine, that’s the time to add moisture. You could add the juice from one lemon or some grated radish.
Graduate to fermenting in a water-sealed ceramic crock. I love the ease and simplicity of fermenting in a jar, but the larger environment of a crock can be a game-changer, both in flavor and moisture.
In addition, brine levels ebb and flow throughout the fermentation process and with temperature fluctuations. There will be copious brine during the first active phase of fermentation and less during the later, quiet stages. Water is naturally pulled back into the cells of the cabbage in the cold of your refrigerator.
How will I know when my sauerkraut is done fermenting?
The easy answer is when the taste and crunch are to your liking. Taste along the way to understand how the flavors evolve over time.
You are introducing air into your jar, but this is a learning process. Wait until you’re past the 7-day mark to avoid disturbing the crucial first stages. When you’re done tasting, repack and push everything below the brine.
You do want to ferment for at least 7-10 days to ensure the bacteria have produced enough lactic acid and the pH of your ferment has dropped to a safe level (below pH 4.0).
If you’re trying to “maximize” the probiotic count—and I’m not sure exactly how/if this is done—one study points to 21 days when numbers peaked.
Can I ferment without salt or make a low-sodium sauerkraut?
Salt is used to establish a safe fermentation environment. You cannot ferment without it.
When you mix salt with your sliced cabbage, the good guys (the salt-tolerant bacteria) grow, thrive, and convert sugars naturally present in vegetables into lactic acid, the preservative. This lactic acid then lowers the pH of your ferment to create an environment in which the salt-phobic, pathogenic bacteria cannot live.
Microbiologists have studied the growth of pathogenic—harmful—and beneficial bacteria in fermentation and have determined that this process safely unfolds at a salinity range (created by the amount of salt you add) of 1.5% to 2.5%.
This is why I have you use a scale to weigh your vegetables and cabbage and then add the right amount of salt to create this recommended salinity range.
Calculating the amount of salt you add by using a measuring spoon generally works but is dependent upon the accuracy of your measuring spoon and the type of salt you’re using. Weighing your salt is even better. For instructions on how to do so, see:
Salt by Weight for Delicious Sauerkraut… Batch after Batch
A low-sodium sauerkraut can be made at the low end of this range (1.5%). For a safe fermentation environment, I do not recommend going any lower.
How long will my sauerkraut last in the refrigerator?
A jar of sauerkraut should easily last a year or longer. That’s the beauty of fermentation. You can enjoy the fruits of your labor—and the work of the microscopic bacteria—for many months.
You can stock your fridge with vegetables fermented at their peak of freshness and then enjoy them throughout the year. Traditionally, sauerkraut was made in the fall for consumption throughout winter when fresh vegetables were scarce.
Now It’s Your Turn. What was the most helpful thing you learned?
The importance of weighing your ingredients?
How to keep your ferment below the brine?
Simple ways to add sauerkraut to your diet?
Or, maybe you have a question about something you read.
Either way, let me know by leaving a comment below right now.
