Vitamin D₂ fortification of Calocybe indica mushroom by natural and artificial UVB radiations and their potential effects on nutraceutical properties

Calocybe indica mushroom was exposed under natural and artificial UVB light to enhance vitamin D₂ contents in the fruit bodies. When Kinetic model was designed to examine the rate of conversion of ergosterol into vitamin D₂ at different time intervals (0, 15, 45, 60 and 90 min), it was found that the conversion was linear with time. The maximum content of vitamin D_2, that is 78.33 µg/g in sunlight and 140.58 µg/g in UVB radiated fruit bodies, was recorded in the samples exposed for 60 min. Interestingly, UVB radiations triggered the synthesis of β-glucan from their actual content (22.42–44.36 g/100 g) and improved the contents of phenols (12.46–47.38 mg GAE/g) and flavonoids (0.85–2.15 mg Quercetin/g). The estimated antioxidant activities, viz., free radical DPPH scavenging activity and ferric reducing antioxidant power was also found to significantly (p < 0.05) increase after 60 min of UVB exposure. For DPPH and FRAP, lowest IC₅₀ values obtained was 1.90 and 4.60 respectively, which are suggestive of high antioxidant capacity. Additionally, the paper also describes how UVB rays chemically altered the scores for all seventeen amino acids that were analyzed.