Vitamin D2 content and antioxidant properties of fruit body and mycelia of edible mushrooms by UV-B irradiation

Our objective was to study the effect of ultraviolet-B (UV-B) light irradiation on the vitamin D2 content of several edible fruit bodies and mycelia and their antioxidant properties. Eleven species of fresh mushroom fruiting bodies, including species from each of the six genera, Agaricus, Agrocybe, Auricularia, Hypsizigus, Lentinula and Pholiota, and five species from Pleurotus genus, were irradiated with UV-B light for 2 h. For three species of mushroom fruiting bodies with excellent vitamin D2 yield, their mycelia were obtained by liquid culture, and subjected to the same time as the UV-B irradiation. Vitamin D2 content of irradiated fruit bodies significantly increased from 0-3.93 to 15.06-208.65 μg/g, of which the amount in golden oyster mushroom increased by a maximum of 204.7 μg/g. Vitamin D2 content in irradiated mycelia of golden oyster, oyster and pink oyster mushrooms increased from 0.28-5.93 to 66.03-81.71 μg/g, respectively. The three irradiated mycelium polysaccharide contents decreased in a range from 1.3% to 24.6%. Overall, EC50 values of non-irradiated and irradiated fruiting bodies and mycelia were 0.92-4.94, 0.20-6.90 and 0.02-0.84 mg/mL for reducing power, scavenging ability and chelating ability, respectively. Although UV-B irradiation influenced the content of ergothioneine, flavonoids and total phenols, these irradiated samples still contained a sufficient amount of these antioxidant components.