Sustainable valorization of mushroom stalks for vitamin D extraction and flour surface functionalization

This study aimed to valorize button mushroom stalks (Agaricus bisporus) to extract vitamin D₂ to fortify flours sustainably. Freeze-dried stalks were subjected to UV-B treatment (280–315 nm) followed by the extraction of vitamin D₂ using conventional (reflux and open water bath saponification) and non-conventional techniques (ultrasonication) to obtain maximal yield. Ultrasonication followed by saponification yielded the highest extract (25.8 mg/g) with optimal vitamin D₂ content (103.08 µg/g), thus attaining a recovery efficiency of 102.6% by the optimized protocol. The hexane (solvent) residue in extracted vitamin D₂ (0.31 ppm) was far less than FDA-approved levels (290 ppm) and the maximum residue limit (MRL) set by the European Union (EU)/Food and Drug Administration (FDA) (1 mg/kg), thereby underscoring the safety and compliance of the extraction method with regulatory standards. Vitamin D₂ enriched extract was used to fortify cereal and millet flours using surface functionalization. The homogeneity of the fortified flours was optimized using a V-blender for 20 min at 20 rpm. The vitamin D₂ content varied between 12 and 13 µg per 100 g of fortified flours. The functional properties of fortified flours, namely, circularity (↑- 26–38%), aspect ratio (↓- 20–49%), Carrs Index (↓- 12–21%), Hausner ratio (↓- 1–4%), and angle of repose (↓- 4–5%) showed marked improvement indicating increased smoothness and flowability. These findings thus emphasize the potential of utilizing button mushroom stalks for extracting vitamin D₂, offering a sustainable and effective means to fortify flours with improved physicochemical and functional properties. Further, studies can be carried out to assess vitamin D₂ potential and efficacy of fortified flours for varied applications in the pharmaceutical and food sectors.