How do I tell if my honey has gone bad?

December 12, 2025 •

4 min read

Archaeologists have found pots of honey thousands of years old in ancient Egyptian tombs that were still edible. While this illustrates honey's incredible shelf life, certain improper storage conditions or contaminants can cause it to spoil.

Quick Summary

Pure, properly stored honey can last indefinitely, but moisture contamination can cause it to ferment. Visible signs of spoilage include off-odors, sour tastes, excessive foam, or mold, differentiating it from harmless crystallization.

Key Points

Check for Fermentation Signs: True spoilage is primarily caused by fermentation from excess moisture, indicated by a sour smell, yeasty taste, or visible bubbles and foam on the surface.
Crystallization is Normal: A cloudy, thick, or grainy texture is natural crystallization, not a sign of spoilage, and actually indicates the honey's purity.
Re-liquefy Crystallized Honey: You can return crystallized honey to its liquid state by placing the sealed jar in a warm (not boiling) water bath.
Store in a Dry, Sealed Container: The best way to prevent spoilage is to store honey in an airtight container in a cool, dry place to prevent moisture contamination.
Trust Your Senses for Off-Flavors: If the honey tastes bitter, sour, or otherwise unpleasant, it may be fermented and should be discarded.
Watch for Rare Mold: Although very rare, if mold is present, the honey should be discarded immediately, as this signifies significant moisture contamination.
Avoid Refrigeration: Storing honey in the refrigerator accelerates crystallization, which is harmless but makes the honey hard to use.

While honey is famously known for its longevity, it is not entirely immune to spoilage. For honey to go bad, it must be contaminated, most often by moisture. A pristine environment with low moisture and high acidity makes honey an inhospitable place for bacteria and microbes to thrive. However, if water gets into the honey, the water content can increase, allowing natural yeasts to begin fermenting the sugars. Learning to identify the key signs of this process is crucial for determining if your honey has truly gone bad.

Recognizing Fermented Honey

Fermentation is the primary way honey spoils. When excess moisture is introduced, wild yeasts can react with the honey's natural sugars, producing alcohol and carbon dioxide. This process creates several tell-tale signs that your honey is no longer suitable for consumption.

Visible Bubbles and Foam: Check the surface of the honey for small bubbles or a layer of foam. This is a direct result of the carbon dioxide being released during fermentation. In a sealed container, this pressure can even cause the lid to bulge slightly.
Off-Putting Smell: Give the honey a sniff. Properly preserved honey has a pleasant, sweet aroma that varies depending on its floral source. Fermented honey will have a distinctly sour, tangy, or yeasty, almost alcoholic, odor.
Sour or Alcoholic Taste: A small taste is often enough to confirm your suspicions. Good honey is purely sweet, but fermented honey will have a sour, bitter, or vinegary flavor. If it tastes unpleasant, it's best to discard it.

Differentiating Crystallization from Spoilage

One of the most common reasons people mistake good honey for bad is crystallization. Crystallization is a natural and completely harmless process that occurs when glucose separates from the water in the honey, forming solid crystals. This is actually a sign of pure, unprocessed honey and not an indicator of spoilage.

The honey's color will become lighter and more opaque, and its texture will become thicker and grainier.
Crystallized honey is still perfectly safe to eat and can be restored to its liquid state by placing the jar in a warm water bath.

Key Factors for Proper Honey Storage

To prevent your honey from going bad in the first place, follow these proper storage techniques:

Store in a cool, dry place: The ideal temperature is between 50 and 70°F (10-20°C). Excess heat can accelerate the degradation of flavor and color.
Use an airtight container: A tightly sealed glass or food-safe plastic container is essential. This prevents moisture from the air from being absorbed, which is the primary cause of fermentation.
Avoid refrigeration: While refrigeration won't spoil the honey, the cold temperature speeds up the crystallization process, making the honey difficult to use.
Use clean utensils: To prevent contamination, use a clean, dry spoon every time you use the honey.

Spoiled Honey vs. Crystallized Honey Comparison


Feature	Spoiled Honey (Fermented)	Crystallized Honey (Normal)
Appearance	May have bubbles, foam on top, or visible mold. Layers may separate unusually.	Becomes cloudy, opaque, and grainy or thickens into a solid mass. Color may lighten.
Smell	Sour, yeasty, or alcoholic odor.	Retains its characteristic sweet, floral aroma.
Taste	Sour, bitter, or vinegary taste.	Tastes just as sweet, though some people perceive a richer flavor.
Health Risk	Contains microorganisms from fermentation; should be discarded.	No health risk whatsoever; it is perfectly safe to eat.
Cause	Contamination with moisture allows yeasts to ferment sugars.	Natural separation of glucose from water, a sign of pure honey.

The Rare Case of Mold

While extremely rare in properly stored honey due to its low moisture content, mold can form if the honey has been exposed to excessive moisture for an extended period. Mold will appear as visible, fuzzy spots on the surface of the honey and indicates that it has been compromised and should be thrown out immediately.

Conclusion

For millennia, honey has been a testament to nature's preservatives, but proper storage remains the key to its longevity. While natural crystallization is a harmless, expected process that indicates a product's purity, true spoilage is the result of moisture contamination leading to fermentation. By relying on your senses—looking for bubbles, smelling for sour odors, and tasting for off-flavors—you can confidently determine the state of your honey. The vast majority of the time, the honey in your pantry is simply crystallized and can be revived with a little warmth. However, any signs of fermentation or mold are a clear signal to discard the product and replace it with a fresh, properly stored jar to enjoy for years to come.

A note on safety

For those interested in the science behind honey's antimicrobial properties, the National Library of Medicine offers detailed research on its chemical composition and its effects on microorganisms. This can provide further insight into why honey is so resistant to spoilage under normal conditions.

A Final Consideration

Another rare scenario is when bees collect nectar from certain toxic plants, which can result in honey that is harmful to humans. Known as 'mad honey' in some regions, this is a very specific form of contamination that does not indicate general spoilage. However, for most consumers, observing the visual and olfactory cues described above is the most reliable method for determining if their honey is safe to use.

Frequently Asked Questions

Pure honey that is stored correctly in a sealed container can last indefinitely and does not technically expire. Spoilage only occurs if the honey is contaminated, typically with moisture, which can cause it to ferment.

No, crystallization is a natural and normal process for pure honey and does not mean it has gone bad. It is caused by glucose separating from the water content and can be reversed by gently warming the jar.

The first signs of fermented honey are often a sour or yeasty smell, and visible bubbles or foam forming on the surface. This is caused by yeasts reacting with the sugar after the honey has absorbed excess moisture.

If your honey is crystallized, you can easily restore it to a liquid state by placing the sealed jar in a bowl of warm water. Stir occasionally until the crystals dissolve, but avoid high heat, which can damage the honey's properties.

It is not recommended to eat fermented honey, as it can have an unpleasant sour or bitter taste and may contain unwanted microorganisms. For safety and taste, it is best to discard any honey showing signs of fermentation.

If your honey has separated into two layers, it is likely due to partial crystallization. The glucose portion has crystallized and settled at the bottom, while the fructose has remained liquid on top. It is still safe to eat.

To prevent honey from spoiling, always store it in a cool, dry place in a tightly sealed, airtight container. This keeps moisture out, which is the leading cause of fermentation.