Integration of ultrasound and microwave pretreatments with solid-state fermentation enhances the release of sugars, organic acids, and phenolic compounds in wheat bran

Wheat bran (WB), a byproduct of milling, is rich in bioactive compounds with significant health benefits. This study aimed to enhance the release of phenolic compounds, sugars, and organic acids from WB by integrating ultrasound (UsP) and microwave (MWP) pretreatments with solid-state fermentation (SSF). UsP and MWP disrupted WB cell walls, followed by SSF with Aspergillus niger. UsP increased total phenolic content by 21.30 % on day 1 of SSF. UsP and MWP boosted the availability of bound phenolic compounds like vanillic acid and dihydroxybenzoic acid. Both pretreatments enhanced antioxidant activity compared to untreated fermented WB, with peak activity on day 5 of fermentation at 1411 ± 5.156 μM Trolox/100 g DW for UsP WB and 291.6 ± 1.092 μM Trolox/100 g DW for MWP WB. This integrated approach improved the extraction efficiency of fermentable monosaccharides, particularly glucose and xylose, offering a sustainable bioprocessing strategy for WB valorization and supporting the circular bioeconomy.