Successive fungal solid-state fermentation and UV-B irradiation: A novel strategy to boost bioactive potential and vitamin D2 levels of corn flour

Abstract

This study introduces a novel biofortification strategy that combines solid-state fermentation (SSF) using edible fungi Pleurotus eryngii and Hericium erinaceus, followed by UV-B irradiation of colonized corn flour, to enhance its vitamin D₂ content and functional properties. UV-B treatment enabled effective photoconversion of ergosterol from both fungal mycelium and the cereal matrix, increasing vitamin D₂ levels up to 18.98 μg/100 g, as confirmed by HPLC. Structural analyses (FTIR, SEM, XRD) revealed reduced starch crystallinity and notable changes in surface morphology. Antioxidant capacity improved significantly, with DPPH radical scavenging activity increasing from 8.61 to 13.72 mg TE/100 g. Techno-functional properties were also enhanced, including water absorption index (from 2.16 to 3.41 g/g) and solubility index (from 0.88 % to 1.63 %). Furthermore, SSF increased the concentration of free amino acids (from 0.05 to 0.31 g/100 g) and bioactive peptides (from 193 to 474 mg/100 g), indicating improved nutritional quality. These findings highlight a sustainable biofortification strategy for developing functional foods enriched with vitamin D₂ and other health-promoting biomolecules, offering a value-added use for agro-industrial substrates.

Keywords: Biofortification; Corn flour; Hericium erinaceus; Pleurotus eryngii; Solid-state fermentation; UV-B irradiation; Vitamin D₂.