Invertase
Lexikon
Invertase is an enzyme that bees add to honey through their saliva while collecting and processing nectar or honeydew.
Invertase is an enzyme that bees add to honey through their saliva while collecting and processing nectar or honeydew. Chemically it is an alpha-glucosidase that mainly splits sucrose and maltose into glucose and fructose. Invertase activity is regarded as a particularly sensitive indicator of ripeness and gentle handling, because the enzyme is already damaged much more severely by heating above 40 degrees than diastase, the other enzyme also present in honey.
The Honey Regulation itself does not set a minimum value for invertase, but for its trademark the German Beekeepers' Association requires at least 64 units per kilogram according to the Siegenthaler measurement method; for naturally enzyme-poor varieties such as germander or robinia honey, 45 units are sufficient, provided the HMF content is at the same time no more than 5 milligrams per kilogram. The German Honey Guidelines additionally distinguish two voluntary quality grades: at least 60 units per kilogram are required in the Auslese category, and at least 85 units per kilogram in the Premium or feine Auslese categories.
In the past, several different measurement methods were used for invertase, such as the Hadorn sucrase number or the Gontarski units, which could not be directly converted into one another. The Lower Saxony State Institute for Apiculture in Celle therefore switched, together with the German Beekeepers' Association, to the more precise and practical Siegenthaler method, without the actual quality level changing as a result. For beekeepers, a low invertase value usually means that the honey was heated too much or stored too long at an unsuitable temperature.