Optimization of the UVB irradiation conditions for the vitamin D2 biofortification of oyster mushroom (Pleurotus ostreatus) using response surface methodology

The rising prevalence of vitamin D deficiency and insufficiency is a growing concern due to its crucial role in bone health and the immune system. The increasing preference for indoor activities, such as work-from-home and online learning setups, reduces sunlight exposure, thereby limiting the body’s natural production of vitamin D. To address this, the study aimed to optimize the UVB-induced vitamin D 2 biofortification process of oyster mushrooms. This approach provides consumers with a protein-rich, vitamin D-fortified food product while also supporting the mushroom industry. The study employed Response Surface Methodology (RSM) with a Central Composite Rotatable Design (CCRD) to optimize three key parameters: temperature, time of exposure, and distance from the UVB source. Results indicated that the optimal irradiation conditions were 34.93 °C, 100 min of exposure, and 30 cm distance from the UVB source, yielding a predicted vitamin D 2 concentration of 18.28±0.38 μg/g fresh weight (FW). However, confirmatory analysis revealed a significantly higher concentration of 20.46±0.80 μg/g FW, supporting the validity of the predicted model and confirming the effectiveness of the radiation chamber. This suggests that one (1) gram of biofortified oyster mushroom could supply the recommended daily dietary intake of 15 μg of vitamin D for adults. A slight browning effect was observed in irradiated mushrooms, with ΔE values of 7.53 for caps and 13.23 for gills compared to fresh samples. Despite the discoloration, the study successfully demonstrated the efficacy of the biofortification process and the industrial applicability of the custom-designed radiation chamber.