Brussels, 03/03/2016. Those prized Burgundy or summer truffles apparently have something more than just the ability to add flavour to fine dishes – they can also resist radioactivity!. Swiss and German researchers have analysed Burgundy truffles collected across regions of central Europe, and found that unlike other fungi, they possess very low levels of radioactive cesium-137 pollutants.
Ever since the 1986 Chernobyl nuclear disaster in the Ukraine, radioactive Cesium particles have been spread by winds and rain over large areas of East and West Europe. “Much of the continent’s topsoil layers are still radioactively contaminated,” says Ulf Büntgen, head of dendroecology at the Swiss Federal Research Institute.
Some forest mushrooms, such as wild porcini, can accumulate dangerous levels of radioactivity originating from the Chernobyl incident. However this radioactive poisoning does not seem to affect the subterranean Burgundy or summer truffles (Tuber aestivum). “We were very surprised that all specimens we analysed exhibited insignificant values of 137Cs,” says Büntgen.
Which is surprising, because many types of fungi, including truffles, grow underground in soil prone to accumulating radioactive pollutants. Deer truffles, for example, which are more appealing to deer or wild boar than to humans, are among the most contaminated fungi. In regions where the radioactive fallout after Chernobyl was most intense, contamination has affected wild animals as well as mushrooms, as evidenced in the meat of red deer and wild boar, which still have high levels of cesium-137.
“The main reason for our focus on the Burgundy truffle is the species’ wide ecological and geographical distribution, which allows us to collect fruit bodies from a wide range of environments. Growth of the Périgord black truffle, in contrast, is restricted to Mediterranean habitats only,” says Büntgen.
The researchers analysed 82 Burgundy truffles collected across Europe between 2010 and 2014. The samples were harvested by trained truffle dogs from different natural habitats in Switzerland, Germany, France, Italy and Hungary.
All the truffles had negligible radioactive contamination, with 137Cs values below the detection limit of 2 becquerels per kilogram. This is far below the tolerance value of 600 becquerels per kilogram, which means the truffles are safe for human consumption, at least in the areas the researchers sampled.
The research team are unsure what their results would be if they had collected samples in areas with known higher levels of radioactive fallout, such as parts of Belarus or central Austria. “We really don’t know,” Büntgen acknowledges. “We will, however, continue to expand our search to include truffles from regions that were so far not considered – the more the better.”
The results to date have been published in the journal “Biogeosciences”. However the exact reason for this resistance to radioactive fallout remains unexplained. The team speculate it could be the way Burgundy mushrooms draw nutrients from the soil compared to other types of fungi. However, they say they need to do more research in this area.
© Philip Hunt, 2016.