The Retention of Vitamin D 2 and 25-Hydroxyvitamin D 2 in Pulse UV-Irradiated Dried Button Mushrooms ( Agaricus bisporus ) after 12 Months of Storage.

Fresh mushrooms exposed to ultraviolet (UV) radiation prior to drying generate high concentrations of vitamin D 2 . The aim of this study was to determine the retention of D vitamers in mushrooms that were pulse UV irradiated, then air dried, and stored for up to 12 months. Fresh button mushrooms ( A. bisporus ) were exposed to pulsed UV radiation (dose 200 mJ/cm 2 , peak of 17.5 W/cm 2 ), air dried and vacuum sealed before being stored in the dark at room temperature. After storage, samples were freeze dried and quantified for D vitamers using triple quadrupole mass spectrometry. After 3, 6 and 12 months of storage, there was 100% (11.0 ± 0.8 µg/g dry weight (DW), 93% (10.1 ± 0.6 µg/g DW) and 58% (5.5 ± 0.6 µg/g DW) retention of vitamin D 2 and 88% (0.14 ± 0.01 µg/g DW), 71% (0.11 ± 0.01 µg/g DW) and 68% (0.1 ± 0.01 µg/g DW) retention of 25-hydroxyvitamin D 2 (25(OH)D 2 ), respectively. Compared to the irradiated dried mushrooms that were not stored, the D vitamer concentration was statistically significantly lower ( p < 0.05) at 6 and 12 months for 25(OH)D 2 and at 12 months for vitamin D 2 . Sufficient vitamin D 2 (99 µg) remained after 12 months storage to provide at least 100% of daily dietary vitamin D requirements in a 20 g serving.