Thixotrophic honey gels in the comb
Thixotropy is a property of certain fluids—including honey—that results in changes in consistency. These fluids are gelatinous when undisturbed but become liquid when they are shaken or stirred. If left to rest, they will revert to the gelatinous state.
Several types of honey are well known for being thixotrophic. Among them are manuka honey (Leptospermum scoparium) from New Zealand and southeast Australia, ling or heather honey (Calluna vulgaris) from Europe, and grapefruit honey (Citrus paradisi).
It is believed that certain proteins are responsible for this behavior in honey. Honeys that are high in protein (up to 1.9%) are more prone to thixotropy than others. Most honeys have only trace amounts of protein and so are unaffected.
While the nutritional properties of honey are not changed by this, the honey is difficult to extract. A regular centrifugal extractor often won’t work unless the honey is agitated first. To do this a number of inventions have appeared, including a device that inserts vibrating pins into every cell. Once vibrated into liquid, the frames are transferred to a regular extractor.
Since this method is expensive and time-consuming, much thixotrophic honey is pressed from the comb. Although this destroys the comb, the wax can be used for other purposes. Alternatively, thixotrophic honey can be sold in its natural state as comb honey.