Sustainable Vitamin D 2 Biofortification of Shiitake Mushrooms by Solar Drying

Vitamin D deficiency affects over 1 billion people and is linked to skeletal conditions such as rickets and osteoporosis, as well as nonskeletal and mental health disorders, including cardiovascular disease, certain cancers, infections, and depression. Limited sun exposure increases the risk, and natural dietary sources of vitamin D are few and predominantly animal‐based. Mushrooms offer a unique nonanimal source of vitamin D 2 (ergocalciferol), synthesized from ergosterol through ultraviolet (UV) exposure. This study evaluated two postharvest treatments—solar drying and artificial UV‐B irradiation—for enhancing vitamin D 2 content and drying kinetics in Lentinula edodes (shiitake mushrooms). Solar drying was conducted under monitored natural conditions, and the drying behavior was analyzed through moisture loss, drying rate (DR), and effective diffusivity. Vitamin D 2 levels were quantified using high‐performance liquid chromatography (HPLC). UV‐B–treated mushrooms had the highest content (19.2 ± 0.3 µg/g), followed by solar‐dried (11.6 ± 0.7 µg/g) and control samples (6.6 ± 0.7 µg/g). As little as 0.78 g of UV‐treated or 1.29 g of solar‐dried mushrooms can meet the recommended daily intake of 15 µg—making them significantly more efficient than most traditional food sources such as eggs or fatty fish and suitable for vegans. Both treatments proved effective and sustainable for vitamin D 2 biofortification in mushrooms.