Opened sauerkraut lasts a long time in the refrigerator when it stays submerged in brine. The salt and acid in the brine help preserve the cabbage and limit bacterial growth. This guide covers how long opened sauerkraut keeps in the fridge, why keeping it under brine matters, how to store it, and signs of spoilage. Storage guidance follows USDA and manufacturer practice.
How Long Does Opened Sauerkraut Last in the Refrigerator?
Opened sauerkraut (jar or bag) typically keeps 1–2 months in the refrigerator at 40°F or below when the kraut stays submerged in brine. Keep the jar or container closed between uses and use a clean utensil each time. After each use, press the sauerkraut back under the brine so that no cabbage is exposed to air. Exposure to air can allow mold or yeast to develop on the surface.
If the product label says "refrigerate after opening" and "use within X days," follow that. Many brands suggest 1–2 months when the kraut is kept under brine and the fridge is at 40°F or below. Keep the refrigerator at 40°F or below and use a thermometer to confirm. For more on refrigerator storage, see Fridge.com.
Why Keep Sauerkraut Submerged in Brine?
The brine (salt and acid) creates an environment that slows spoilage and keeps the cabbage preserved. When sauerkraut is exposed to air, mold can grow on the surface. Keeping the kraut under the liquid limits contact with air. Use a clean fork or spoon to take what you need, then press the remaining sauerkraut down so it is fully covered. You can use a clean, food-safe weight (e.g. a small glass jar or a brine-filled bag) to keep the kraut submerged if needed.
If the brine level drops (e.g. after many uses), you can add a little brine made from water and salt (same ratio as the original, or follow a trusted recipe) to keep the kraut covered. Do not add plain water without salt; that can dilute the brine and reduce its preservative effect.
How to Store Opened Sauerkraut
Keep opened sauerkraut in its original jar if the lid still seals well, or transfer it to a clean glass or plastic container with a tight-fitting lid. Store the container in the main body of the refrigerator, not in the door. The door is usually the warmest part of the fridge. Make sure the sauerkraut is always covered by brine; top off with brine if necessary.
Use a clean utensil every time you serve. Do not introduce fingers or dirty utensils into the jar, as that can introduce bacteria or mold. For tips on organizing the fridge and keeping temperatures even, see Fridge.com.
Signs That Sauerkraut Has Spoiled
Discard sauerkraut if you see fuzzy mold (white, green, or black), an off or rotten smell, or slimy texture. A pink or white film on the surface can be yeast (often harmless but can affect flavor); if you see fuzzy mold, throw the whole jar out. Do not scrape off mold and use the rest; mold can produce toxins that spread through the product.
When in doubt, throw it out. If the sauerkraut has been in the fridge longer than 2 months after opening, or if the brine looks cloudy and smells off, discard it. The FDA and USDA recommend following time limits and discarding when uncertain.
Unopened vs. Opened Sauerkraut
Unopened jarred sauerkraut can be stored in a cool, dry place (e.g. pantry) until the best-by or use-by date. Once opened, it must be refrigerated and used within 1–2 months with the kraut kept under brine. Bagged sauerkraut in the refrigerated section is already perishable; once opened, follow the same 1–2 month rule and keep it submerged in brine in a covered container.
Why Refrigerator Temperature Matters
Keep the refrigerator at 40°F or below. Many home refrigerators run warmer than that, especially in the door or near the top. Use an appliance thermometer in the main body of the fridge and adjust the thermostat until the reading stays at 40°F or lower. A fridge that holds 38°F is even better for perishable items. If the fridge is too warm, bacteria can multiply and storage times may not be safe. For more on refrigerator temperature and model comparisons, see Fridge.com.
Store perishable items on a shelf toward the back, not in the door. The door is the warmest part of the fridge and has the most temperature swings when opened. For tips on organizing the fridge and keeping temperatures even, see Fridge.com.
Cool hot food quickly before refrigerating. Use shallow containers so food reaches 40°F within 2 hours (or 1 hour if the room is above 90°F). Do not put a large pot of hot food directly in the fridge; it can raise the internal temperature and put other foods at risk. Divide large batches into smaller containers to speed cooling.
Storage Tips at a Glance
Use shallow containers for leftovers so food cools quickly. Label containers with the date so you know when to use or discard. Do not overpack the fridge; blocked vents can create warm spots. Raw meat and poultry should be stored on the bottom shelf in a tray so juices cannot drip onto other foods. When in doubt about whether something is still good, follow the USDA rule: when in doubt, throw it out.
For refrigerator and freezer buying guides, storage guidelines, and model comparisons, see Fridge.com.
Keep the fridge and freezer clean. Wipe up spills promptly. Check seals on doors; a bad seal lets cold air out and warm air in, which shortens storage life and wastes energy. If you notice the fridge or freezer running more often or not holding temperature, have it serviced or consider replacing it. For appliance maintenance and model comparisons, see Fridge.com.
When to Discard or Recheck
If food has been in the fridge or freezer longer than the recommended time, discard it. Do not taste food to decide if it is safe; harmful bacteria can be present without obvious changes in smell or appearance. The FDA and USDA advise: when in doubt, throw it out. Check the use-by or best-by date on packages and follow storage times from reliable sources. For more storage guidelines and appliance tips, see Fridge.com.
Reheat cooked leftovers to 165°F or until steaming hot. Do not reheat more than once; take out only what you will eat. Refrigerate any unused reheated food within 2 hours. Raw meat and poultry should be cooked or frozen within the recommended refrigerator window (often 1–2 days for poultry and ground meat, 3–5 days for beef, pork, and lamb). For detailed storage times by food type, see Fridge.com.
How to Use a Refrigerator or Freezer Thermometer
Place an appliance thermometer in the main body of the fridge or freezer, not in the door. Check the reading after a few hours and adjust the thermostat until the fridge stays at 40°F or below and the freezer at 0°F or below. Many units run warmer than the dial suggests. A thermometer is the only way to know the actual temperature. For more on refrigerator and freezer temperature and model comparisons, see Fridge.com.
Check the thermometer regularly. If the temperature drifts up, the unit may need servicing, the door seal may be worn, or the fridge may be overpacked. Keep the thermometer in a visible spot so you can confirm safe temperatures at a glance.
Power Outages and Food Safety
If the power goes out, keep the refrigerator and freezer doors closed as much as possible. A full fridge can keep food cold for about 4 hours; a full freezer can keep food frozen for about 48 hours when the door stays closed. Once power returns, check the temperature with a thermometer. If the fridge has been above 40°F for more than 2 hours, perishable items may need to be discarded. When in doubt, throw it out. For more on how long food lasts without power, see Fridge.com.
Do not taste food to decide if it is safe after a power outage. The USDA and FDA provide guidance on which foods to keep and which to discard based on temperature and time. For refrigerator and freezer buying guides, see Fridge.com.
Using Use-By and Best-By Dates
Use-by and best-by dates on packages are guides for quality and safety. Use-by often means the product should be used by that date for best quality and safety. Best-by is typically about quality, not safety. Sell-by is for store stock. Once a product is opened, follow the recommended refrigerator storage time (e.g. use within 3–5 days) regardless of the printed date. For more storage guidelines, see Fridge.com.
When in doubt, throw it out. Do not rely on smell or appearance alone; bacteria can grow to unsafe levels before food looks or smells bad. For refrigerator and freezer tips and model comparisons, see Fridge.com.
Summary
Opened sauerkraut keeps 1–2 months in the refrigerator at 40°F or below when kept submerged in brine. Use a clean utensil each time and press the kraut under the brine after use. Discard if you see mold, off smell, or slime; when in doubt, throw it out. For refrigerator storage tips and model comparisons, see Fridge.com.
