Enhancement of vitamin D2 in edible mushroom using ultraviolet irradiation and assessing its storage and cooking stability

Abstract

Purpose The purpose of this study was to optimize the parameters for enhancing the vitamin D2 formation in three edible mushroom varieties, namely, shiitake mushroom (Lentinula edodes), white button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus) using ultraviolet (UV) irradiation. Design/methodology/approach Freshly harvested mushrooms were irradiated with UV-B and UV-C lamps. Further, mushrooms were treated with UV-B at a distance ranging between 10 and 50 cm from the UV light source, for 15–150 min, to maximize the conversion of ergosterol to vitamin D2. Analysis of vitamin D2 content in mushrooms before and after UV exposure was done by high pressure liquid chromatography (HPLC). Findings HPLC results showed a significant (p < 0.001) increase in vitamin D2 levels of shiitake (17.3 ± 0.35 µg/g), button (24.9 ± 0.71 µg/g) and oyster (19.1 ± 0.35 µg/g) mushrooms, irradiated with UV-B at a distance of 20–30 cm for 120 min. Further, stability studies revealed that vitamin D2 levels in UV-B-irradiated mushrooms gradually increased for 48 and 72 h of storage at room and refrigeration temperatures, respectively. During cooking operations, 62%–93% of vitamin D2 was retained in UV-B-irradiated mushrooms. Originality/value This study describes the most effective parameters such as ideal wavelength, mushrooms size, duration of exposure and distance from UV sources for maximum vitamin D2 formation in edible mushrooms using UV irradiation. Further, assessment of vitamin D2 stability in UV exposed mushrooms during storage period and cooking operations has been carried out. In addition, this study also provides a comparison of the vitamin D2 levels of the three widely cultivated and consumed mushroom varieties treated simultaneously under similar UV exposure conditions.