Melissopalynological knowledge regarding the uniflorality of honeys: the case of under-represented pollen

Melissopalynological knowledge, regarding the uniflorality of honeys, in terms of pollen content, depends on the plant source, but, in many cases, it is difficult to establish the threshold of pollen percentage for a honey to be considered unifloral. This research aims to increase knowledge for the classification of unifloral honeys through pollen analysis. The use of fresh experimental beehives placed under controlled conditions in 11 different specific areas of Euphorbia resinifera (resin spurge) enabled the production of the purest possible honey samples, which could then serve as a reference for testing uniflorality of this type of honey. The experimentally obtained results of the pollen analysis of these pure honey samples revealed a low absolute number of pollen grains and a low percentage of pollen of E. resinifera, which confirms the under-representation of the pollen of E. resinifera in honey labelled as this type. The pollen analysis enabled a combination of pollen grains to be established which greatly facilitates the differentiation of this honey type. Furthermore, we propose that the threshold that delineates the percentage of pollen necessary for this honey type to be considered unifloral can be lower than 10% if combined with a high percentage of the sum of Ceratonia siliqua/Eryngium f./Capsella f./Lactuca f. pollen. Using this approach, the uniflorality was tested of ten honey samples sold commercially as resin spurge using the aforementioned criteria.