When Honey Ferments: What Happened and What Can You Do With It?

Honey is one of those foods we usually think of as almost impossible to spoil. But honey begins as nectar, which contains a much higher percentage of water. Honey bees remove excess moisture through evaporation and other processes, transforming nectar into the concentrated, low-moisture food we recognize as honey. When too much moisture remains in the honey or honey absorbs moisture after harvest, the increased water availability can create conditions that allow naturally occurring yeasts to become active.

As fermentation begins, honey may develop bubbles or foam, become thinner, and develop a fruity, yeasty, alcoholic, or sour aroma and flavor. For beekeepers, fermentation is something we generally try to prevent. Understanding how moisture, yeast, storage conditions, and crystallization affect honey can help explain why fermentation occurs.

Why Does Honey Ferment?

Honey naturally contains yeasts. Most remain inactive because honey has a high sugar concentration and low moisture content, which limits the water available for microbial growth. However, some yeasts are specially adapted to survive in high-sugar environments and are known as osmophilic yeasts. When honey contains enough moisture to support their growth, these yeasts can become active, multiply, and begin fermenting the sugars in honey (Snowdon & Cliver, 1996).

During fermentation, the yeasts convert sugars into alcohol and carbon dioxide. Carbon dioxide is responsible for the bubbles and foaming that can occur as honey ferments (Chirife et al., 2006).

Water Activity Is a Big Part of the Story

One of the most important concepts when discussing honey fermentation is water activity.

Water activity is not simply the amount of water in a food. Instead, it refers to how much of that water is available for microorganisms to use.

Honey typically has a very low water activity because its high sugar concentration limits the water available for microbial growth. This is one of the reasons honey is naturally resistant to microbial growth. Research has demonstrated a strong relationship between moisture content and water activity in honey, including in honey samples with moisture contents ranging from 15% to 21% (Chirife et al., 2006). This is why moisture content is so important to beekeepers.

How Does Honey Get Enough Water to Ferment?

One of the most common reasons honey ferments is that it is harvested before the bees have removed enough moisture from the nectar. If honey is extracted while it still contains too much moisture, it is more susceptible to fermentation because the higher moisture level provides more available water for naturally occurring yeasts.

Honey can also absorb moisture from the surrounding environment. Honey is hygroscopic, meaning it can absorb water from the air. As a result, storage conditions can affect honey's moisture content even after extraction.

Temperature can matter as well. Microorganisms in honey are affected by both moisture and temperature, making these important factors to consider when preventing microbial growth and spoilage (Snowdon & Cliver, 1996).

Crystallization can also affect the amount of water available to microorganisms. When glucose crystallizes, it removes glucose from the liquid portion of the honey. This leaves a higher proportion of water in the remaining liquid, which can increase water activity. Researchers studying 49 crystallized honey samples found that this increase in water activity can sometimes allow naturally occurring yeasts to multiply and contribute to fermentation (Zamora & Chirife, 2006).

How Do You Know If Honey Is Fermenting?

There are several things you may notice when honey begins to ferment. Bubbles or foam are among the most obvious signs. Fermentation produces carbon dioxide, which can become trapped in the honey and appear as bubbles or foam (Chirife et al., 2006).

The honey may also become thinner or more fluid than it was originally.

The aroma can change as well. Fermenting honey may develop a fruity, yeasty, wine-like, or alcoholic smell. The flavor may also become noticeably different, developing a tangy, sour, or slightly alcoholic taste (Snowdon & Cliver, 1996).

Not every change in honey means fermentation. Crystallization, temperature changes, and natural differences between floral sources can affect how honey looks, smells, and tastes. However, when bubbling occurs along with noticeable changes in aroma and flavor, fermentation becomes much more likely.

What Can You Do With Honey That Has Fermented?

If honey has begun fermenting, that does not necessarily mean it has become completely useless. What you do with it depends on the extent of fermentation, its appearance and aroma, and how you intend to use it.

One possibility is mead.

Mead is an alcoholic beverage made by fermenting honey with water and yeast. If honey has already begun fermenting, it may seem like an obvious candidate for mead making. However, spontaneous fermentation is unpredictable. You do not know exactly which microorganisms are present, how much fermentation has already occurred, or what other changes may have taken place. Microorganisms naturally present in honey can affect its quality and stability when conditions are favorable for their growth (Snowdon & Cliver, 1996).

For that reason, fermented honey should not simply be assumed to be ready-made mead. If you want to make mead, it is better to approach it as a controlled fermentation process using appropriate sanitation, a known yeast strain, and established mead making practices.

Fermented honey can also be used as a culinary ingredient if it has a clean, pleasant, fermented flavor and shows no signs of spoilage. Its sweet-and-tangy or slightly fermented flavor may work well in sauces, marinades, glazes, salad dressings, or baked goods.

However, fermentation and spoilage are not necessarily the same thing. A pleasant wine-like, fruity, or slightly sour aroma is different from visible mold or a rotten or putrid odor. If there is visible mold or an unmistakably rotten or putrid odor, I would not recommend trying to rescue the honey.

Can You Prevent Honey From Fermenting?

For beekeepers, the best approach is to prevent fermentation before it begins

One of the most important steps is monitoring honey moisture before extraction and bottling. A refractometer is a useful tool for measuring moisture content because appearance alone cannot reliably indicate whether honey contains enough water to support yeast activity. Research has demonstrated a strong relationship between moisture content and water activity in honey, supporting the importance of moisture measurement when evaluating honey stability (Chirife et al., 2006).

Storage matters too. Honey should be kept in clean, tightly sealed containers and protected from moisture and humid air. Even honey that has a sufficiently low moisture content when bottled can absorb moisture over time if it is repeatedly exposed to humid conditions.

Fermented Honey Can Teach Us Something

Finding fermented honey can be frustrating after all the work that goes into producing, extracting, and bottling it. But fermentation can also tell us something about what happened. It can lead us back to questions about moisture content, whether the bees had sufficiently dehydrated the nectar, storage conditions, humidity, temperature, and yeast activity.

Honey is remarkably stable because of its chemistry. Its high sugar concentration, acidity, and low water activity make it difficult for most microorganisms to grow. However, honey is not completely immune to microbial activity (Snowdon & Cliver, 1996).

Once fermentation begins, the honey changes. It may no longer be the honey you intended to bottle, but that does not necessarily mean it has no further use. Depending on its condition, it may be suitable for certain culinary applications or serve as a reminder of the chemistry and microbiology taking place in something as seemingly simple as a jar of honey.

For beekeepers, understanding why honey ferments is just as valuable as knowing how to prevent it. Monitoring moisture, understanding storage conditions, and recognizing the signs of fermentation can help protect the quality and stability of the honey we work so hard to produce.

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This article is provided for education and does not constitute medical advice. Statements about hive products reflect the current state of research, which is ongoing. Consult a qualified healthcare provider before beginning any therapy.

References:

Chirife, J., Zamora, M. C., & Motto, A. (2006). The correlation between water activity and % moisture in honey: Fundamental aspects and application to Argentine honeys. Journal of Food Engineering, 72(3), 287–292. https://doi.org/10.1016/j.jfoodeng.2004.12.009

Snowdon, J. A., & Cliver, D. O. (1996). Microorganisms in honey. International Journal of Food Microbiology, 31(1–3), 1–26. https://doi.org/10.1016/0168-1605(96)00970-1

Zamora, M. C., & Chirife, J. (2006). Determination of water activity change due to crystallization in honeys from Argentina. Food Control, 17(1), 59–64. https://doi.org/10.1016/j.foodcont.2004.09.003