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