Like every other question in the bee business, this one can be answered with two words: “It depends.” In short, the stability of infused honey varies with the amount of water added during the infusion process.
Fresh fruits, vegetables, roots, stems, and leaves are all loaded with water. Honey is hygroscopic, meaning it draws water from the surrounding environment. So when fresh ingredients are added to honey, water is drawn out of the plant cells and into the honey. This extra water can cause problems.
Although honey is highly resistant to microbial growth, the resistance is due to several factors including its acidity, its hygroscopic properties, and its low water activity (see below). But when you add water to honey, the honey becomes diluted. Diluted honey is less hygroscopic, less acidic, and the water activity increases. Left at room temperature, honey with too much “wet stuff” added will soon mold or ferment.
Water changes everything
The water activity (aw) of a food is used to predict the growth of bacteria, yeast, and mold. Water activity can be defined as “the partial vapor pressure of water in a substance divided by the partial vapor pressure of pure water under the same conditions.” Foods such as meat, fish, and bread have an aw of greater than 0.95, which means they can rapidly spoil.
According to the Food Safety Site at Clemson University, the acidity and the water activity are the most predictive numbers when it comes to food spoilage. If the pH and water activity are too high, even a dangerous food-borne pathogen like Clostridium botulinum can gain a foothold. C. botulinum requires a pH of 4.6 or greater and water activity of 0.92 or greater in order to grow and produce toxin.
According to the National Honey Board, properly cured honey has a pH that falls between 3.4 and 6.1. The average, though, is about 3.9. In addition, honey has an aw between 0.5 and 0.6. Together, the pH and the aw keep the honey safe. But it doesn’t take much water to raise both.
For infused honey, dry ingredients are best
The take-home message here is that if you infuse honey, you should use dry ingredients in order for the honey to remain stable at room temperature. If you infuse honey with fresh ingredients, it should be treated like any other perishable and kept in the refrigerator.
Remember than any ingredients you add to honey are going to carry a variety of spores. Dry herbs and spices are not sterile. Instead they owe their keeping quality to being dry (that is, they have a low aw). Since dry ingredients contain little water, the aw of the honey plus dried add-ins remains low.
Fresh herbs and spices are not sterile either, and they carry water that can raise both the aw and the pH of the honey. Perhaps a small amount of added water will have little effect, but where do you draw the line? Most often, contamination will reveal itself in the form of fermentation, mold growth, or a musty smell which is enough to warn you off.
Wet infusions need a label
However, If you are going to sell the infused honey or give it away, it is best to stay with dry ingredients. Or, at the very least, include emphatic instructions for safe storage. Since most people consider honey to be shelf stable, they may not recognize that honey infused with fresh ingredients has the potential to spoil.
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