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.