137Cs, 40K, and K in raw and stir-fried mushrooms from the Boletaceae family from the Midu region in Yunnan, Southwest China.

The parallel batches of the same species and geographical origin mushrooms both raw and stir-fried were investigated to get an insight into the content and intake of 137Cs, 40K, and K from mushroom meals. The Boletaceae family species (Baorangia bicolor, Boletus bainiugan, Butyriboletus roseoflavus, Retiboletus griseus, Rugiboletus extremiorientalis, and Sutorius magnificus) were collected from the Midu County (Dali Bai Autonomous Prefecture) in 2018. The activity concentrations of 137Cs in the caps of dried raw mushrooms were in the range 14 ± 1 Bq kg-1 dry biomass (db) (R. griseus) to 34 ± 2 Bq kg-1 db (R. extremiorientalis), and in stems from 16 ± 1 Bq kg-1 db (B. bicolor and B. bainiugan) to 23 ± 1 Bq kg-1 db (R. extremiorientalis). The mean activity concentration in the whole fruiting bodies in all six species was 18 ± 4 Bq kg-1 db. The activity concentrations of 137Cs were roughly the same in both dehydrated materials, stir-fried, and raw mushrooms, while the contents of 40K and stable K were around 2- to 3-fold smaller in stir-fried than raw product. The raw and stir-fried mushrooms on a whole (wet) weight basis showed activity concentrations of 137Cs in the range from 1.2 to 3.2 Bq kg-1 ww (mean 1.9 ± 0.6 Bq kg-1 ww) and 6.0 to 9.4 Bq kg-1 ww (mean 7.0 ± 1.2 Bq kg-1 ww), respectively. Evidently, when expressed on a whole (wet) weight basis, the cooked mushrooms showed on average around 3.5-fold greater activity concentration of 137Cs when compared with raw mushrooms. The 137Cs, 40K, and total K enrichment in stir-frying (in a whole (wet) weight basis for the meal), confronted with the results for dehydrated raw and fried mushrooms, show the direct correlation with loss of mass (largely moisture) during the cooking procedure but not much of 137Cs and 40K. Edible wild mushrooms from Yunnan were little contaminated with radiocaesium. As assessed, the mean radioactivity dose from natural 40K in around 9.3-fold exceeded the dose obtained for artificial 137Cs from stir-fried mushroom meals, which both were very low doses.