Ultraviolet irradiation:: The generator of Vitamin D2 in edible mushrooms

Fresh Shiitake mushrooms (Lentinula edodes), Oyster mushrooms (Pleurotus ostreatus), Button mushrooms (Agaricus bisporus), and Abalone mushrooms (Pleurotus cystidus) were irradiated with Ultraviolet-A (UV-A; wavelength 315-400 nm), Ultraviolet-B (UV-B; wavelength 290-315 nm), and Ultraviolet-C (UV-C; wavelength 190-290 nm). Irradiation of each side of the mushrooms for I h, was found to be the optimum period of irradiation in this conversion. The conversions of ergosterol to vitamin D-2 under UV-A, UV-B, and UV-C were shown to be significantly different (p < 0.01). The highest vitamin D-2 content (184 +/- 5.71 mu g/g DM) was observed in Oyster mushrooms irradiated with UV-B at 35 degrees C and around 80% moisture. On the other hand, under the same conditions of irradiation, the lowest vitamin D-2 content (22.9 +/- 2.68 mu g/g DM) was observed in Button mushrooms. (c) 2005 Elsevier Ltd. All rights reserved.