Concentration of vitamin D2 in white button mushrooms (Agaricus bisporus) exposed to pulsed UV light

Enrichment of vitamin D₂ in Agaricus bisporus white button mushroom (WBM) using continuous UV light needs a longer exposure time, which can lead to discoloration. Using a Xenon pulsed UV light source, the yield of vitamin D₂ was evaluated in freshly harvested button mushrooms and mushroom slices after exposure to 2.5, 3, 6 and 9 pulses of UV light at an average dose of 1.150 J/cm² energy per pulse. Increase in vitamin D₂ content was proportionate to the number of pulses of UV light. There was no difference in the vitamin D₂ content of mushrooms between 200 g and 500 g punnets for the corresponding number of pulses (737 ± 81, 847 ± 38, 1148 ± 182, 1611 ± 444% versus 747 ± 48, 911 ± 35, 1307 ± 109, 2028 ± 181% Daily Value/serving, respectively; P > 0.05). Mushrooms in the top layer showed significantly higher amounts of vitamin D₂ content than those in the bottom layer of a 500 g punnet (657 ± 22, 796 ± 76, 1433 ± 138, 1878 ± 178% versus 129 ± 60, 237 ± 117, 403 ± 35, 830 ± 257% DV/serving, respectively; P < 0.01). A single layer of sliced mushrooms (∼5 mm thick) showed higher amounts of vitamin D₂ content than sliced mushrooms packaged together after pulsed UV light exposure (7882 ± 1074, 6867 ± 944, 10,826 ± 472, 13,001 ± 1635% versus 1221 ± 281, 1293 ± 210, 1598 ± 207, 2018 ± 459% DV/serving, respectively; P < 0.001). Discoloration of whole or sliced mushrooms was not observed. Thus, pulsed UV light provides a highly effective method for increasing vitamin D₂ levels in A. bisporus white button mushroom.