Oxidized high-amylose starch as pickering stabilizer for oil-in-water emulsion and delivery of bioactive compound

Polysaccharide based emulsions have received considerable attention due to their biodegradability, biocompatibility and food-safety. In this study, oxidized high-amylose starch (OHAS) is adopted for stabilization of oil-in-water (O/W) emulsion. Results showed that OHAS with oxidation degree of 90% (DO90-OHAS) exhibited higher wettability with three-phase contact angle of 70.6°. The obtained emulsion was stable within a wide range of different solution condition, with pH ranging from 3 to 7, salt concentration as high as 1.0 M and temperature ranging from -25 to 80 ℃. The gel-like network structure of DO90-OHAS effectively stabilized the emulsion and prevented the aggregation of oil droplets under different pH, as evidenced by confocal laser scanning microscopy (CLSM) observation. Furthermore, DO90-OHAS based emulsion prepared at different pH showed satisfactory long-term storage stability (up to 30 days). The fabricated emulsion was utilized for encapsulation of hydrophobic bioactive substances, with ∼72.5% encapsulation efficiency for β-carotene. The DO90-OHAS based emulsion enabled the controlled-release of β-carotene in vitro, with antioxidant activity maintained ∼50% of initial activity when exposed to elevated temperature (80°C). This research may provide a new avenue for OHAS based Pickering emulsions preparation and bioactive components delivery.