Quick Answer
Once opened, sauerkraut should be transferred to an airtight container and stored in the refrigerator. An opened jar of sauerkraut will last about 4-6 weeks when properly stored in the fridge. The keys to maximizing sauerkraut’s shelf life are keeping it cold (below 40°F) and limiting exposure to air. Air can cause oxidation and aerobic bacterial growth on raw, fermented sauerkraut. Canning jars, Mason jars, and other glass jars with tight-fitting lids make excellent containers for preserving leftover sauerkraut. Plastic bags and containers can also work but may be more likely to introduce small amounts of air over time.
Explaining Sauerkraut Storage
Sauerkraut is a traditional fermented food made from finely shredded cabbage and salt. The lactic acid bacteria naturally present on cabbage leaves thrive in a salty, anaerobic environment and produce lactic acid as they ferment the cabbage over 2-4 weeks. This process results in sauerkraut’s distinctive tangy, sour flavor.
Sauerkraut can be purchased pre-made or homemade. Store-bought sauerkraut is pasteurized for food safety purposes, which destroys active bacteria and limits how long it can be stored after opening compared to raw, unpasteurized sauerkraut. Either way, exposing sauerkraut to air starts to degrade quality and reduce shelf life. Here is more detail on how to maximize storage time after opening sauerkraut:
Refrigerate Immediately
As soon as a jar or bag of sauerkraut is opened, transfer it to an airtight container and refrigerate. The cool temperatures of the refrigerator (optimally below 40°F) dramatically slow the growth of bacteria and other microbes that could spoil the sauerkraut or make it unsafe to eat. Prompt refrigeration is key when dealing with any perishable food, especially fermented items like sauerkraut that can quickly deteriorate with exposure to air and higher temperatures.
Avoid Temperature Fluctuations
Try to maintain consistent refrigerator temperatures. Sauerkraut lasts longer when stored at a stable, cold temperature. Temperature fluctuations can accelerate spoilage. Avoid repeatedly opening and closing the refrigerator door and limit how often the sauerkraut container is removed. Monitor refrigerator temperatures and adjust accordingly if the temperature rises above 40°F for extended periods. Consider using a refrigerator thermometer.
Use Airtight Storage Containers
Transferring opened sauerkraut to an airtight glass or plastic container prevents air from contacting the sauerkraut and introduces less oxygen compared to the original packaging. Exposure to oxygen can cause aerobic bacterial growth, oxidation, and other detrimental effects. Wide-mouth Mason jars or other jars designed for canning are a great option since they form a tight seal. Make sure to leave at least 1 inch of headspace between the sauerkraut and lid. Other reusable airtight containers like food storage containers are fine too. If using plastic bags, opt for thicker freezer bags designed to remove air and check periodically for leaks.
Limit Sauerkraut’s Exposure to Air When Removing Some to Eat
Whenever the storage container is opened and sauerkraut removed for eating, limit how much the remaining sauerkraut is exposed to air. Remove only the amount needed, quickly reseal the container, and place back in the refrigerator promptly. Discard any sauerkraut that seems discolored or smells unpleasant instead of resealing it in the container.
Consume Within 4-6 Weeks
Properly stored in the refrigerator, an opened jar of pre-made pasteurized sauerkraut or sauerkraut packed in vinegar will keep for 4 to 6 weeks. Raw, unpasteurized sauerkraut has a shorter shelf life closer to 2-3 weeks once exposed to air. Homemade sauerkraut also has a shorter shelf life than commercial products designed for prolonged storage. Discard any sauerkraut that develops an off odor, appearance, or texture. As a fermented product, sauerkraut can spoil rapidly if not refrigerated. When in doubt, remember the old adage, “When in doubt, throw it out.”
How to Recognize Spoiled Sauerkraut
Be alert for signs that opened sauerkraut has spoiled and should be discarded:
Appearance
- Soft texture
- Discoloration
- Dry, shrunken appearance
- Mold growth
- Sliminess
Sauerkraut past its prime often loses its crunchy texture and starts to turn soft. Its color may also become dull or darkened. Shriveled, dried up sauerkraut means it has probably dried out and spoiled. The presence of fuzzy mold is a definite sign to throw it away. Slimy sauerkraut accompanied by an unpleasant odor indicates unwanted bacterial growth.
Smell
- Rotten, putrid odor
- Vinegar-like smell
- Alcoholic aroma
- Ammonia smell
Unpleasant odors like rotten eggs, garbage, vinegar, alcohol, or ammonia are red flags that sauerkraut has spoiled and should not be eaten. Even storage in the refrigerator cannot prevent spoilage forever. Sauerkraut’s signature sour tang should develop into an unpleasant pungent smell.
Taste
- Sharp, vinegary bite
- Bitter flavor
- Sour, acidic taste
The sourness of bad sauerkraut becomes harsh and extremely acidic on the palate. Rancid or bitter undertones are another warning sign. If your sauerkraut tastes unpleasantly sharp or vinegary, that’s a clue it should be discarded.
How to Store Sauerkraut to Maximize Freshness
Here is a summary of the key storage methods to preserve sauerkraut’s quality and freshness after opening:
Use a Container with an Airtight Seal
Glass jars with tight-fitting lids, like Mason jars, are ideal. Plastic containers and freezer bags also work if properly sealed.
Minimize Air Exposure
Limit how much air contacts the sauerkraut when removing some to eat. Reseal promptly. Keep the container ratio of sauerkraut to air space high.
Refrigerate at 40°F or Lower
Cold refrigerator temperatures slow microbial growth and deterioration. Monitor that the refrigerator maintains this temperature range.
Keep Consistent Temperatures
Avoid temperature fluctuations that can accelerate spoilage. Don’t open the refrigerator door frequently. Store container toward the back of the fridge.
Use Sauerkraut Within 4-6 Weeks
Consume opened pasteurized or vinegar-packed sauerkraut within 4-6 weeks. Raw, unpasteurized sauerkraut has a shorter shelf life around 2-3 weeks. Discard moldy, slimy, or foul-smelling sauerkraut.
Freeze for Long Term Storage
Freezing sauerkraut can extend its shelf life to 6-8 months. Thaw in the refrigerator before eating. Freezing stops fermentation and preserves quality.
Frequently Asked Questions
Can you freeze sauerkraut to make it last longer?
Yes, freezing sauerkraut can extend its shelf life. Sauerkraut that is frozen properly in an airtight container can usually last 6 to 8 months in the freezer before deteriorating in quality. Make sure it is frozen rapidly at 0°F. Thaw frozen sauerkraut in the refrigerator before eating.
What happens if you don’t refrigerate sauerkraut after opening?
Leaving opened sauerkraut unrefrigerated can quickly lead to spoilage caused by microbial growth. Pasteurized sauerkraut may last a week or two, while raw sauerkraut will deteriorate much faster. Always refrigerate opened sauerkraut as soon as possible to maximize freshness and prevent food safety issues.
Can you eat sauerkraut that has mold on it?
No, sauerkraut that has visible mold growth should always be discarded. The mold may also produce toxins or penetrate deep into the sauerkraut that may not be visible. Mold is a clear sign that sauerkraut has been stored for too long and spoiled. When in doubt, do not eat moldy sauerkraut.
How can you tell if opened sauerkraut has gone bad?
Signs that opened sauerkraut has spoiled and should be thrown out include an off smell, unpleasant taste, soft slimy texture, dry shriveled appearance, discoloration, and mold growth. Trust your senses. If sauerkraut smells or tastes bad, looks funny, or feels slimy, err on the side of caution and do not eat it.
Can sauerkraut last at room temperature if the jar hasn’t been opened?
An unopened jar of commercially packaged, refrigerated sauerkraut can be left unrefrigerated for 1-2 months before opening thanks to the acidic environment and pasteurization killing most microbes. However, refrigeration will always extend the shelf life. Once opened, sauerkraut must be refrigerated.
Conclusion
Maximizing sauerkraut’s shelf life after opening simply requires limiting its exposure to air, keeping it refrigerated at 40°F or below, and consuming within 4-6 weeks. Transfer any leftover sauerkraut to an airtight container and monitor closely for any signs of spoilage like odor, appearance, or texture changes. Proper storage and vigilance for spoilage can help you safely enjoy the unique flavor and live microbial benefits of sauerkraut without having any go to waste. Follow these sauerkraut storage recommendations and your opened jar should remain fresh and tasty for weeks to come.