One spoonful of Estonian honey contains 50,000 grains of pollen

ERR research portal is introducing the prizewinning One-Minute Lecture series in which Tallinn University researchers give answers to fascinating questions in short lectures. “To produce one kilogramme of honey, bees should visit four million flowers,” said Liisa Puusepp, a Research Fellow at the TU Institute of Ecology. 

There are several ways of determining the plant origin of honey. When a beekeeper knows the flora around his hives, he can evaluate the potential honey yield and where his bees are flying. However, you can find more detail by looking inside honey – the picture can be incredibly diverse and interesting.

“Besides honey being mostly a solution of sugars, it includes plenty of pollen grains from the plants that the bees visit,” explained Liisa Puusepp. “Size, shape and surface patterns of plants are species-specific. Of course these are miniscule bits. But if we look at these under a microscope, we can trace plants that produce honey and the origin of nectar.”

Liisa Puusepp started with pollen analysis of honey about 15 years ago as a student in order to describe the pollen spectrum of different honeys and its application in assessing the floristic and geographic origin of honey. Although her research subject has changed, she still continues to analyse pollen simply because of her own interest and fulfils orders for beekeepers and collects data.

Recently she published a research article “Pollen analysis of honey from the Baltic region, Estonia” in an international research journal, Grana, on the basis of an 11-year data series, including more than 300 Estonian honey samples, which summarises quite thoroughly the work of the last decade. Altogether more than 120 different pollen groups were registered.

It appears that most Estonian pollens are polyphloric, which means that they contain several different pollen groups and no group is dominant. On average, one sample contained 13 pollen groups, mostly containing pollen grains of different Rosaceae, Brassicaceae and Salix. Pollen grains of Trefoil and other Fabaceae are also presented abundantly. Some honey samples could still be categorised as monophloric (which means that one plant is dominant). Examples of these are heather, willow, linden, shamrock, stonecrop and raspberry honey.

Besides the plant origin, pollen concentration is also considered as a quality indicator of honey. “In the light of global research, we can claim that Estonian honey samples are of medium pollen concentration, but this depends a lot on the plant type where a bee collects nectar for producing the honey,” said Puusepp. “One gram of Estonian honey on average contains 10,000 pollen grains, which means that one teaspoon contains 50,000 pollen grains.”

This series of long data collection enables us to describe temporal changes in the pollen composition of honey. “It has been noticed that the proportion of rape and other Brassicaceae has increased in honey samples and the proportion of heather and Rosaceae is decreasing,” stated Puusepp. “The same tendency has been described in Finland as well. Therefore, nowadays it is no wonder if you find sunflower pollen grains in a sample of Estonian honey, for example. Another consideration is that a high proportion of sunflower pollen grains would make us suspect that the honey sample is from Ukraine, not Estonia.”

Studying honey is interesting to people at many levels. A beekeeper ‘labels’ his product and wants confirmation of its origin. A client who wishes to eat honey also wants confirmation of its origin. Estonian consumers prefer Estonian honey. Therefore we need to control the marketing in order to ensure that foreign honey is not sold under the label of Estonian honey. Of course, Puusepp’s scientific curiosity lies behind all these studies. She investigates whether there are changes in pollen composition of honey samples, whether and how precisely the plant and geographical origin of honey can be determined, as well as the time and place of gathering.