Retention of Antioxidants and Vitamin D2 in the Golden Oyster Mushroom Pleurotus citrinopileatus (Agaricomycetes) under Different Drying and UV Exposure Conditions

This study evaluated the impact of different drying methods, sun drying, solar drying, and oven drying, at 26 ± 2°C, 50 ± 2°C, and 40 ± 2°C, respectively, on the bioactive properties of Pleurotus citrinopileatus. The phytochemical [2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, phenols, flavonoids, tannins and ascorbic acid] and nutritional properties (moisture, ash, fat, fiber, carbohydrates and protein) were analyzed. Additionally, the effect of UV irradiation (5, 10, 15, 20, 25 and 30 min) on vitamin D₂ content was assessed. Drying methods significantly influenced the bioactive composition of P. citrinopileatus, with solar drying yielding the highest DPPH scavenging activity (75.04 ± 0.30%), phenolic content [1.03 ± 0.01 mg gallic acid equivalents (GAE)/g], flavonoid content [0.37 ± 0.01 mg quercetin equivalents (QE)/g], tannins (8.04 ± 0.20 mg GAE/g), and ascorbic acid (22.67 ± 1.33 mg/100 g). Solar drying also preserved the highest protein (29.00 ± 1.53%) and carbohydrate (49.17 ± 1.17%) content, making it the most effective drying method. Although UV exposure generally enhances vitamin D₂ synthesis in mushrooms, our results showed a decline in vitamin D₂ content beyond 15 min of exposure, likely due to degradation from overexposure, decreasing from 60.88 μg/100 g at 5 min to 47.31 μg/100 g at 15 min, with no detectable levels beyond 15 min. Our findings confirm that solar drying is the most effective method for preserving antioxidant and vitamin D₂ content in P. citrinopileatus for preserving the nutritional and phytochemical integrity of P. citrinopileatus, while UV exposure must be carefully controlled to retain vitamin D₂ content.