Contrasting structural and functional changes in enzymatically pretreated coffee peel insoluble dietary fiber induced by alkaline hydrogen peroxide and ultrasonication.

Native coffee peel insoluble dietary fiber (N-IDF) was enzymatically treated to obtain a common precursor (E-IDF), which was subsequently modified by alkaline hydrogen peroxide (EA-IDF) or ultrasonication (EU-IDF) to enable a direct comparison of the two modification routes. All treatments significantly reduced particle size (p < 0.05); EU-IDF-300 had the smallest D50 (40.90 μm) and the highest specific surface area (308.47 m2/kg). EA-IDF exhibited a more open matrix and greater improvements in hydration and in vitro adsorption. EA-IDF-1.0% showed the highest swelling capacity (17.67 mL/g) and glucose adsorption capacity (5.24 mmol/g at 200 mmol/L), while both EA-IDF samples had higher cholesterol adsorption capacity than N-IDF and E-IDF at pH 7.0 (p < 0.05). XRD and monosaccharide profiling revealed structural and compositional differences between treatments, whereas FTIR detected no new functional groups. The contrasting responses of EA-IDF and EU-IDF provide a basis for selecting modification routes for specific technological applications.