Peanut butter is a popular spread made from ground, roasted peanuts. It comes in two main styles: natural peanut butter and commercial peanut butter. Natural peanut butter contains only peanuts and sometimes salt. Commercial peanut butter often has added sugars, oils, and other ingredients.
Some people believe that natural peanut butter should be refrigerated after opening, while others think it can be stored at room temperature like commercial peanut butter. So what really happens if you don’t refrigerate natural peanut butter?
Does natural peanut butter need to be refrigerated?
The short answer is no, refrigeration is not strictly necessary for natural peanut butter. However, there are some benefits to storing opened natural peanut butter in the fridge:
- Refrigeration will slow down the separation process. Natural oil separation is normal in peanut butter, but chilling it will keep the oil distributed for longer.
- It helps prevent mold growth. The lack of preservatives in natural styles makes them more prone to mold.
- Refrigeration extends shelf life. An opened jar will stay fresher longer when chilled.
So while refrigeration is not mandatory, it can help natural peanut butter maintain optimal texture and freshness if you won’t be eating it quickly. Many natural peanut butter brands recommend refrigerating after opening.
What causes natural peanut butter to go bad?
Natural peanut butter has a shorter shelf life than commercial peanut butter due to a lack of preservatives and stabilizers. Opened natural peanut butter will go bad from:
- Moisture loss – Exposure to air evaporates some of the oils.
- Oil separation – The oils start to separate from the peanut solids.
- Rancidity – The fats oxidize and become smelly and unpleasant tasting.
- Mold growth – Lack of preservatives makes it prone to mold.
Refrigerating natural peanut butter after opening helps limit these spoilage factors. The cold temperature preserves moisture, delays oil separation, slows rancidity, and inhibits mold growth. However, natural peanut butter can still eventually go bad in the refrigerator once opened.
How long does opened natural peanut butter last when unrefrigerated?
When stored properly, an unopened jar of natural peanut butter will stay fresh for about 9-12 months past the best by date. After opening peanut butter, its shelf life decreases due to exposure to air, varying temperatures, and moisture loss. When left unrefrigerated, opened natural peanut butter generally lasts:
- 2 to 3 months – Kept in a cool, dry pantry away from heat sources. The oils may start separating at the end of 3 months.
- 1 to 2 months – If stored in a warm environment or frequently left out on the countertop at room temperature when used.
For best quality and freshness, use refrigerated natural peanut butter within 4 to 6 months. Discard if it smells rancid or shows any mold growth.
How to tell if natural peanut butter has gone bad?
Watch for these signs that opened natural peanut butter has spoiled and should be discarded:
- Appearance – Mold spots, unusual coloring, excessive oil separation.
- Texture – Runs very thin, is gritty, or becomes very stiff.
- Smell – Smells rancid, rotten, or funky.
- Taste – Tastes bitter, sour, or just off.
A little bit of oil separation is normal in natural peanut butter. However, if the peanut butter is very runny with a thick layer of oil on top, it has gone bad.
What is the best way to store natural peanut butter?
To maximize freshness and shelf life of natural peanut butter:
- Refrigerate after opening.
- Store in an airtight container to limit air exposure.
- Keep it away from heat and light, which speed up oil separation.
- Stir occasionally to redistribute the oils.
- Use clean utensils each time to avoid introducing bacteria.
- Write the date opened on the jar and discard after 3-4 months (refrigerated) or 2-3 months (pantry).
Can you freeze natural peanut butter?
Yes, natural peanut butter can be frozen to extend its shelf life. To freeze:
- Make sure the peanut butter is fresh, not already separated or spoiled.
- Store it in an airtight freezer bag or container, leaving some headspace to allow for expansion.
- Exclude as much air as possible to prevent freezer burn.
- Lay flat in the freezer to maximize surface area contact.
- Defrost in the refrigerator before use to prevent oil separation.
Properly frozen natural peanut butter can last 6 to 9 months in the freezer. It may still require stirring once thawed to reincorporate the oils.
Can you eat natural peanut butter that has separated?
Yes, natural peanut butter with some oil separation can be safely consumed provided it shows no signs of spoilage like mold, sour odor, or rancid taste. To reincorporate separated peanut butter:
- Stir well before use until creamy and uniform.
- Store upside down or on its side to help redistribute the oil layer.
- Mix in a food processor or blender to fully combine it.
- A small amount of oil on top is normal, but if excessive separation has occurred it may have gone rancid.
Should you mix separated peanut butter or discard it?
With minor oil separation, the peanut butter is fine to mix and consume if it smells and tastes normal. But peanut butter with extensive oil separation often has an increased risk of rancidity. Use your judgment based on these factors:
| Mix and eat | Consider discarding |
|---|---|
| Small layer of oil on top | Thick layer of oil on top |
| Hasn’t exceeded shelf life | Shelf life has clearly passed |
| Smells and tastes fresh | Smells or tastes rancid |
| Was refrigerated after opening | Left unrefrigerated too long |
| Stored in a cool spot | Stored in a hot environment |
When in doubt, use your best judgment based on inspection and smell. Rancid peanut butter does not taste good and eating large amounts may cause digestion issues.
Tips for preventing natural peanut butter from separating
To help keep natural peanut butter from separating for as long as possible:
- Store upside down or on its side after opening.
- Choose peanut butter with less oil like brands with palm oil instead of extra virgin olive oil.
- Avoid stirring with a knife which introduces air. Mix with a clean spoon instead.
- Press plastic wrap directly on the surface after using to exclude air.
- Buy only what you will use within 2-3 months.
- Immediately refrigerate after use.
Some separation over time is inevitable in natural peanut butter. But following proper storage methods and using older jars first can minimize oil separation.
How to mix natural peanut butter and commercial peanut butter
It’s possible to mix natural and regular commercial peanut butter together. This can help tone down separation issues in the natural style. To mix them:
- Choose a commercial peanut butter with similar ingredients to your natural brand.
- Stir the separated natural peanut butter first to reincorporate the oils.
- Measure out equal parts of each peanut butter.
- Mix together thoroughly until creamy and uniform.
- Store in an airtight container in the refrigerator.
- Use within 2-3 months for best quality.
When blended equally, the resulting peanut butter will have a consistency and stability similar to mainstream commercial brands.
How to soften hardened natural peanut butter
Over time in the refrigerator, natural peanut butter can stiffen and become difficult to scoop. To soften:
- Use a spoon handle or knife to puncture holes and gently stir the peanut butter before removing the lid.
- Let the jar sit at room temperature for 30-60 minutes to warm up.
- Submerge the closed jar in a bowl of warm water for 5-10 minutes.
- Remove the lid and microwave 10-20 seconds at a time until spreadable.
- Transfer to a bowl and mix vigorously with a spoon.
- Avoid overheating as this can cause oil separation later.
Hardened or cold peanut butter can also be softened more gradually by refrigerating with the lid slightly loosened.
Conclusion
While refrigerating natural peanut butter after opening is best for longevity, it’s not strictly required. Properly stored in the pantry, opened natural peanut butter will keep for 2-3 months. Look for signs of spoilage like excessive oil separation, mold, rancid smells, or bitter taste before consuming. Storing peanut butter upside down or mixing in oil can help temper separation issues. Hardened peanut butter can be softened to spreadable texture with gentle warming techniques. Following proper storage methods and using older jars first will help maximize the shelf life of natural peanut butter.