Uncapped honey fermenting in the comb
To produce honey, bees collect nectar from flowers and add enzymes from their honey stomachs. Once the mixture is stored in cells, the bees fan it with their wings until it dehydrates to a moisture content of about 16 to 18.5 percent. If the moisture content is higher than that, the bees simply won’t cap it. If cold weather arrives before the honey is capped, it will sit open in the hive and may eventually ferment.
Fermentation is the process of changing carbohydrates to ethanol and carbon dioxide. Fermentation in honey is no different than the process used in brewing alcoholic beverages. The yeasts that cause this biological process are found naturally in the environment and are called “wild” yeasts. The alcoholic content of fermented honey is not high—perhaps one or two percent—but knowing what to do with it is problematic.
Bubbles and a yeasty odor
Uncapped honey that has not fermented looks like normal honey. Once it starts to ferment, the cells are filled with bubbles and the odor of yeast can become quite rank. Sometimes foam oozes out of the cells and collects under the frames.
As a general rule, beekeepers who extract and bottle honey like to keep the uncapped cells to about 10 percent of the total. However, some go as high as 33 percent, which may require further dehydrating of the honey in order to keep it from fermenting in the bottle.
A lot of controversy surrounds the question of how harmful fermented honey is to bees and whether it can be fed back to bees. Alcohol is poisonous to them (as it is to most living things) but bees probably eat a certain amount of it in the normal course of hive life. I’m quite sure a small amount of fermented honey will not harm a hive, and many beekeepers agree.
What to do with it
However, if you have gallons and gallons of the stuff, I wouldn’t use it as a primary food source. Again, if you imagine bees in nature, you can see that they might encounter some fermented honey—but not barrels of it. The amount they eat should be a small part of their total diet.
Some beekeepers deal with the problem by extracting and boiling the honey which drives off the alcohol and kills many of the yeast. The downside is that boiling changes the properties of honey and increases the percentage of hydroxymethylfurfural.
For hobby beekeepers with only a few frames that contain uncapped honey, you can often give them a good shake and most of the uncured nectar will fly out of the cells. What little remains will probably not affect either the bees or the extracted honey. Use the “10 percent” rule and you shouldn’t have any problems.
Honey Bee Suite