Optimization of UV irradiation conditions for the vitamin D2-fortified shiitake mushroom (Lentinula edodes) using response surface methodology.

The aim of this study was to investigate the optimal conditions to process vitamin D2-fortified shiitake mushrooms through UV irradiation for industrial processing. Response surface methodology was used to identify the optimum conditions of the following highly influential factors on vitamin D2 synthesis: temperature, UV dosage, and moisture content. The optimal conditions of those variables were 40.56 °C, 36.27 kJ/m2, and 80.46%, respectively, and UV dosage was the most effective variable. The amount of vitamin D2 obtained under the optimal conditions was 29.87 ± 1.38 μg/g (dry mass: DM) which was well matched with the predicted value of 32.33 μg/g DM. The effects on the texture and color of shiitake mushrooms were also evaluated after the fortification process under the optimal conditions, and no adverse effects were observed compared to those of fresh shiitake mushrooms.