Vitamin D2, Ergosterol, and Vitamin B2 Content in Commercially Dried Mushrooms Marketed in China and Increased Vitamin D2 Content Following UV-C Irradiation

Mushrooms are a great source of vitamin D and vitamin B; however, the content of these vitamins in dried mushrooms has not fully been investigated. Thus, the objectives of this study were to determine the contents of vitamin D, ergosterol, and vitamin B in commercially dried edible mushrooms in China and to investigate the effect of UV-C irradiation on fresh mushrooms. Among the 35 species of dried mushrooms considered for this study, the average ergosterol content was 1.98 mg/g, while the average vitamin D content was 16.88 µg/g. The average vitamin B content in dried mushrooms was 12.68 µg/g. Fresh shaggy ink caps and oyster mushrooms, when exposed to UV-C at 254 nm at a dose of 0.25 J/cm for 10, 30, and 60 min, showed significantly (p < 0.05) increased vitamin D2 content (229.7 and 67.0 µg/g, respectively) as compared to its fresh counterparts. The conversion of ergosterol to vitamin D induced by UV-C irradiation at 0.25 J/cm was significant (p < 0.05). In conclusion, dried commercial mushrooms have higher contents of ergosterol and vitamin D than fresh mushrooms. UV-C radiation can be used to increase vitamin D content in mushrooms.