Selenium and organic- and inorganic-Hg in stir-fried mushrooms†

Selenium (Se) and co-occurring total and organic mercury (THg and o-Hg) were investigated in wild edible mushroom species collected from Central Yunnan, Southwestern China. The regional terrain is known for being Se-deficient and consequential diseases such as Keshan and Kashin–Beck are endemic. “Pseudo-porcini” species, Boletus bainiugan and Butyriboletus roseoflavus, were Se-rich (means of 28 and 13 mg kg⁻¹ dry weight), while six other species contained tenfold lower concentrations. The two bolete species contained 4.1 and 2.8 mg kg⁻¹ dw of THg and 0.047 and 0.038 mg kg⁻¹ dw of o-Hg, respectively, with means of 0.22 and 0.01 mg kg⁻¹ dw in other species. Stir-frying enhanced analyte concentrations, favoring Se relative to Hg, in most species, particularly boletes. Health risk-benefit assessments of the stir-fried mushrooms using both the Se : Hg molar quotient and the Se health benefit value (HBVSe) showed strongly positive values for boletes and were favorable for other species except for Scleroderma yunnanense.