Abstract:

Vitamin D, an essential compound for humans, is derived from provitamin D by ultraviolet irradiation. The most
important members of the vitamin D family are vitamin D2 and vitamin D3. Edible fungi contain a high amount of provitamin D2
(ergosterol), which can be converted to vitamin D2 by ultraviolet irradiation. The contents of ergosterol and vitamin D2 in
different growth ways of edible fungi are outlined in this paper, beginning with the mechanism of vitamin D2 formation from
ergosterol. The emphasis is placed on discussing some major factors influencing the conversion of ergosterol to vitamin D2 in
edible fungi subjected to ultraviolet irradiation, including edible fungi species, bands of ultraviolet, irradiation dose and time,
and irradiated parts, growth stage and moisture content of edible fungi, as well as reaction temperature, in order to provide a
reference to increase the yield of vitamin D2 in edible fungi under ultraviolet irradiation．

Key words: VD2, edible fungi, ultraviolet irradiation, ergosterol