Enhancing the storage stability of Pickering emulsion using esterified buckwheat starch with improved structure and morphology

Abstract

The present study was aimed to enhance the storage stability of oil–in–water Pickering emulsion using esterified buckwheat starch. The starch esterified with 0.5–3% octenyl succinic anhydride (OSA) showed degree of substitution between 0.0032 ± 0.001 and 0.0229 ± 0.003, respectively. The esterification increased the particle size (7.44 ± 0.03–7.60 ± 0.03 μm), changed the smooth surface morphology to rough and converted the sharp-edged granules to irregular shapes. Major structural changes were occurred in the amorphous region, confirmed by X-ray diffraction as crystallinity decreased (25.6–20.9%) after modification. FTIR showed a peak at 1750 cm−1 and Nuclear magnetic spectra showed specific peaks at 0.80–0.89 and 1.2–2.7 ppm, which confirmed OSA modification. The amphiphilic granules with improved structure and morphology were utilized to stabilize oil–in–water Pickering emulsion prepared by ultrasonication with 30 and 40% amplitude for 2 and 4 min. The stable Pickering emulsion with 3.43–86.86 μm droplet diameters was observed to be formed with 3% OSA starch particle, treated with 40% amplitude for 4 min. However, the emulsions prepared at higher amplitude (40%) showed better results for all modified starch. The study confirms the potential of buckwheat starch for non-conventional applications (Pickering emulsion) using novel technologies like ultrasonication.