Glossary
Honey that has undergone yeast fermentation due to excess moisture content (above 20%), producing alcohol, carbon dioxide, and off-flavors. In beekeeping, fermented honey represents a quality failure. In fermentation arts, intentionally fermented honey is the basis of mead production.
Honey's legendary shelf stability depends on its low moisture content creating an environment where nothing can grow. When moisture rises above approximately 20%, osmophilic yeasts (Zygosaccharomyces species) that exist dormant in virtually all honey can activate and begin fermenting the sugars. The result is alcohol production, carbon dioxide gas (causing bubbling or foam), sour or alcoholic off-flavors, and a product that is no longer appetizing as table honey.
Fermentation usually indicates one of several failures: harvesting too early (extracting honey before bees have capped it, indicating moisture content above 18% to 20%), improper storage (leaving honecombs or jars open in humid environments), or crystallized honey absorbing atmospheric moisture (the crystal surface is hygroscopic and can pull water from humid air, creating a wet layer on top of dry crystals where yeast can grow).
Early signs of fermentation include tiny bubbles on the honey's surface, a slight foam layer, and a faintly sour or wine-like smell when you open the jar. Advanced fermentation produces obvious foam, a distinctly alcoholic or vinegar-like odor, and a fizzy or bubbly texture. The honey may expand in the jar, and containers may bulge from carbon dioxide pressure.
When fermentation is controlled and intentional, honey becomes mead: one of the oldest alcoholic beverages in human history. Meadmakers deliberately dilute honey to a specific gravity that supports fermentation, pitch selected yeast strains, and control temperature and nutrients to produce wines that range from bone-dry to dessert-sweet. What is a flaw in beekeeping is an art form in fermentation.
Mildly fermented honey is not dangerous but may have unpleasant sour or alcoholic flavors. It can be used in cooking (the off-flavors dissipate with heat) or in homemade mead. Heavily fermented honey with strong vinegar-like odors is best discarded or used as a meat marinade rather than eaten directly.
Ensure honey is fully ripened before extraction (check that 80% or more of cells are capped). Keep sealed jars at room temperature (65 to 80 F). Avoid storing open containers in humid environments. If you notice early fermentation signs, refrigerate the honey to halt yeast activity.
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