How Long Sauerkraut Lasts in the Refrigerator and When It Goes Bad

Sauerkraut stays safe to eat for months in the refrigerator, but it will eventually spoil

Unopened sauerkraut in a jar lasts 4 to 6 months in the refrigerator, sometimes longer. Once you open it, it stays good for another 1 to 3 months if you keep the lid on between uses and don't let it dry out. The fermentation process that created the sauerkraut in the first place—the salt and the acid—acts as a natural preservative, which is why it lasts so much longer than fresh cabbage would.

The exact timeline depends on how the sauerkraut was made and stored. Commercially canned sauerkraut that has been heat-processed lasts longer than raw fermented sauerkraut from a jar. Homemade sauerkraut, which is usually not heat-treated, tends to have a shorter window. Temperature matters too: the colder your refrigerator stays, the slower any remaining fermentation happens, and the longer the sauerkraut holds.

Key Takeaways

• Unopened sauerkraut lasts 4 to 6 months in the refrigerator; opened jars last 1 to 3 months if kept sealed between uses.
• Sauerkraut goes bad when it develops a slimy texture, turns brown or dark, smells rotten instead of sour, or grows visible mold.
• Store sauerkraut in a glass jar with the lid sealed tightly, and keep it toward the back of the refrigerator where temperature is most stable.
• The brine (the salty liquid) protects the cabbage, so always keep the sauerkraut submerged and never scoop it out with a wet spoon.
• Homemade sauerkraut spoils faster than store-bought because it has not been heat-treated and may contain more active bacteria.

Signs that sauerkraut has gone bad

A sour smell is normal—that is what sauerkraut is supposed to smell like. A rotten, sulfurous, or ammonia-like smell means it has spoiled and should be thrown out. The smell is the clearest warning sign because it comes from bacterial breakdown that has gone past fermentation into decay.

Look at the texture and color. Fresh sauerkraut is firm and pale to golden. If it turns slimy, mushy, or dark brown, it has begun to break down. Visible mold—white, green, or black—anywhere in the jar means the whole batch should go. Even if mold is only on the surface, fermented foods are porous and the mold has likely spread into the brine.

If the sauerkraut tastes off—not sour but unpleasant, or if it tastes flat and lifeless—trust that signal. Taste a small spoonful first if you are unsure. Your mouth will tell you if something is wrong before your stomach has to.

How to store sauerkraut so it lasts as long as possible

Keep sauerkraut in a glass jar with a tight-fitting lid. Plastic containers let air through over time, and metal lids can corrode from the acid in the brine. Glass and a good seal are what you need. Store the jar toward the back of the refrigerator, not on the door, because the door temperature fluctuates every time you open it. The back stays coldest and most stable.

Always keep the sauerkraut submerged in its brine. The liquid is what protects it from air and bacteria. If the level drops, add a little salt water (about 1 teaspoon of salt per cup of water) to bring it back up. Never use a wet spoon to scoop sauerkraut out of the jar—moisture introduces bacteria. Use a clean, dry fork or spoon, and wipe the rim of the jar before closing the lid.

If you transfer sauerkraut from a large jar to a smaller one to save space, do it when the jar is nearly empty. This reduces the air pocket above the brine, which slows oxidation and keeps the sauerkraut fresher longer.

The difference between fermented and heat-treated sauerkraut

Store-bought sauerkraut comes in two types: raw fermented and pasteurized (heat-treated). Raw fermented sauerkraut contains live bacteria that continue to ferment slowly in the refrigerator. Pasteurized sauerkraut has been heated to kill those bacteria, so it stops fermenting and lasts longer—often 6 months or more unopened.

Homemade sauerkraut is almost always raw fermented, which means it has a shorter shelf life than the pasteurized store versions. The live bacteria are part of what makes homemade sauerkraut valuable nutritionally, but they also mean it will eventually consume the remaining cabbage and go soft. This is not the same as spoiling—it is just the natural end of fermentation—but the texture and flavor will decline.

Check the label on store-bought sauerkraut to see if it says "raw" or "unpasteurized." If it does, treat it more like homemade and plan to use it within 1 to 2 months of opening. If the label does not mention fermentation or says "pasteurized," it will last longer.

What happens if sauerkraut sits out on the counter

Sauerkraut left at room temperature will continue to ferment and will spoil much faster than it would in the refrigerator. Within a few days to a week, depending on how warm your kitchen is, it will become soft, the brine may become cloudy, and the smell will shift from sour to unpleasant. Warm temperatures speed up bacterial activity, and not all of that activity is the good kind.

If sauerkraut has been out of the refrigerator for more than 2 hours, especially in a warm room, it is safer to throw it out. The risk is not worth it. Fermented foods are generally safe because of their acidity, but once the balance tips toward spoilage, pathogens can grow quickly at room temperature.

Can you freeze sauerkraut to extend its life

Yes, sauerkraut can be frozen, though the texture will change. The cabbage becomes softer and loses some of its crunch when it thaws. The flavor stays intact, and the nutritional value is not harmed. Freezing stops all fermentation and bacterial activity, so frozen sauerkraut will keep for several months.

To freeze sauerkraut, transfer it to a freezer-safe container or bag, leaving a little headspace because the brine will expand as it freezes. Thaw it in the refrigerator before using, not on the counter. Once thawed, use it within a few days, just as you would with refrigerated sauerkraut. Do not refreeze it.

Freezing works best if you know you will not use the sauerkraut within its normal refrigerator window. It is a good way to preserve homemade sauerkraut if you made a large batch and want to keep some for later.

How to tell if homemade sauerkraut is still fermenting or has spoiled

Homemade sauerkraut that is still fermenting will have a pleasant sour smell, stay firm, and may show small bubbles in the brine or a slight cloudiness. These are all signs of active fermentation and mean it is still good. The smell should be tangy and appetizing, not rotten.

Spoiled homemade sauerkraut smells bad—sulfurous, musty, or like ammonia. The cabbage becomes slimy or mushy. The brine may turn brown or develop a film on top. If you see any of these signs, discard the whole batch. The risk of foodborne illness from spoiled fermented food is real, even though fermented foods are generally safer than non-fermented ones.

If you are unsure whether homemade sauerkraut is still good, the smell test is your best guide. If you would not want to smell it again, do not eat it.

Frequently Asked Questions

Is it safe to eat sauerkraut if it has a white film on top?

A thin white film (called kahm yeast) on the surface of homemade sauerkraut is not mold and is not dangerous, though it can affect flavor. You can skim it off with a clean spoon. However, if the film is thick, fuzzy, or any color other than white, it is mold and the sauerkraut should be discarded.

Can sauerkraut go bad if the jar is not sealed perfectly?

A loose or imperfect seal lets air in, which speeds up spoilage. The sauerkraut will not go bad immediately, but it will last only a few weeks instead of months. If you notice the lid is not sealing well, transfer the sauerkraut to a jar with a good seal, or use it sooner.

Does sauerkraut go bad faster if I keep opening and closing the jar?

Yes. Every time you open the jar, you introduce air and potentially bacteria. Minimize how often you open it, and always use a clean, dry utensil. If you use sauerkraut frequently, keeping it in a smaller jar reduces the air space and the number of times you have to open a large container.

What is the difference between sauerkraut that tastes flat and sauerkraut that has gone bad?

Flat-tasting sauerkraut is old but still safe—the fermentation has slowed and the flavor has faded. Spoiled sauerkraut tastes actively unpleasant: soapy, rotten, or off in a way that makes you want to spit it out. If you have to think about whether it tastes bad, it probably does not taste bad yet. Trust your instinct.

Can I add more salt to sauerkraut to make it last longer?

Adding salt to the brine can slow fermentation and spoilage, but it will also make the sauerkraut much saltier. A better approach is to keep the existing brine level stable by adding plain salt water if needed, and to store the jar in the coldest part of your refrigerator.