Honey can change texture over time without anything being wrong. It may become paler, thicker or grainy — usually the result of natural crystallisation. Fermentation looks and smells different. In this guide, we explain how to inspect a jar, separate normal changes from warning signs and decide what to do next.
What is fermented honey?
Fermentation can begin when naturally occurring yeasts have enough water to grow and break down some of the sugars. This produces gas and compounds that alter the aroma and flavour, which is why moisture content matters so much.
Honey is hygroscopic: it absorbs moisture from the surrounding air. A loosely closed lid, a damp spoon or storage in a steamy place can therefore raise the risk. Under the international Codex standard for honey, honey sold as such must not have begun to ferment or effervesce.
How can you tell whether honey is fermenting?
We recommend looking for a combination of signs rather than judging the jar by one detail. Persistence matters: activity that continues while the honey is standing is more significant than a few bubbles created by handling.
Bubbles or foam that keep returning
A thin layer of foam, tiny bubbles rising repeatedly or a gently fizzy-looking surface can point to gas production. An unusual hiss or pressure when the lid is opened adds to the concern. A few bubbles immediately after stirring or pouring, however, are not enough to prove fermentation.
A sour, yeasty or alcoholic smell
Honey should retain an aroma consistent with its floral origin, even if its intensity changes over time. A distinctly sour, fermented, yeasty or alcohol-like smell is a stronger warning sign, particularly when it appears alongside persistent bubbles. There is no need to taste honey that already seems altered just to confirm a suspicion.
An unusually thin or separated texture
A very runny layer beneath a denser one, combined with foam or an unusual smell, may also accompany fermentation. Separation on its own is not proof; consider it alongside the other signs and the way the jar has been stored.
What does not necessarily mean fermentation?
Crystallisation is normal
Honey that turns opaque, creamy or grainy is not automatically spoiled. Crystallisation happens when some of its sugars naturally form crystals. The speed varies with floral origin, temperature and composition. It does not mean that the jar is past its date or unsuitable to eat.
In partially crystallised honey, more water can remain in the still-liquid portion. This is one reason careful storage remains important, but crystals alone are not a sign of fermentation.
Air bubbles after handling
Pouring, stirring or gently warming honey can trap air. Those bubbles usually remain still or fade gradually. By contrast, activity that continues without handling — especially with foam, pressure or a sour smell — deserves more caution.
Why might honey begin to ferment?
- Excess moisture in the honey: the main factor behind fermentation.
- A jar left open: honey can absorb moisture from the air, especially in a humid kitchen.
- A wet utensil: repeatedly introducing even small drops of water can weaken storage stability.
- A loose or damaged lid: it no longer protects the contents as effectively.
- Unsuitable storage: heat and frequent temperature swings can speed up changes in the product.
What should you do if you suspect fermentation?
If several signs appear together — persistent bubbles, pressure, foam and a sour or yeasty smell — we recommend that you do not serve or eat the honey. Close the jar, keep it away from other foods and, if it was recently purchased or only just opened, contact the seller with the batch number and photographs.
Do not try to “rescue” it by heating or refrigerating it. Those steps may alter the texture or temporarily slow the activity, but they do not restore the honey to its original quality. If doubt remains about an already opened jar, discarding it is the prudent choice.
How to reduce the risk at home
- Always use a clean, completely dry spoon.
- Close the lid as soon as you have taken the honey you need.
- Keep the jar in a dry cupboard, away from direct light and heat sources.
- Avoid the edge of the sink, the top of the dishwasher and areas exposed to steam.
- Follow the storage instructions on the label.
These simple habits also help protect honey’s aroma and texture. To explore different floral profiles and find one that suits the way you enjoy honey, browse our honey collection.
In short
Crystallisation makes honey opaque or grainy and is a natural change. Fermentation is more likely to show as ongoing activity — bubbles, foam or pressure — together with a sour, yeasty or alcoholic smell. We advise considering several signs together and not consuming the product if uncertainty remains. A dry spoon, a tightly closed lid and storage away from moisture are the best everyday precautions.
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