Integrating the modified amphiphilic Eleocharis tuberosa starch to stabilize curcuminoid-enriched Pickering emulsions for enhanced bioavailability, thermal stability, and retention of the hydrophobic bioactive compound.

Abstract

The study involves the modification of a non-conventional starch isolated from the under-utilized variety of Chinese water chestnut (CWC (Eleocharis tuberosa) and integrating it to fabricate stabilized and curcumin-enriched Pickering emulsions with enhanced bioavailability, thermal stability, and retention of encapsulated curcumin. A time-efficient, semi-dried esterification method was used to prepare modified amphiphilic starches using 3, 6, or 9 % (w/v) octenyl succinic anhydride (OSA) and characterized through degree of substitution (DS), contact angle, particle size, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and in-vitro digestibility. Moreover, Pickering emulsions were formulated using CWCS-OSA at 3 %, 6 %, or 9 % concentrations to serve as a carrier for curcumin to improve its water solubility and storage stability. The research investigated Pickering emulsions' encapsulation efficiency, curcumin retention, emulsifying properties, micromorphology, temperature stability, and bioaccessibility. Results showed that CWCS-OSA, with an OSA concentration between 3 % and 9 %, exhibited a degree of substitution (DS) ranging from 0.017 to 0.031 and an expansion in contact angle from 68.36^o to 85.45^o. CWCS-9%OSA showed the highest encapsulation efficiency at 89.4 % and maintained an emulsification index above 80 % during a 10-day storage period. A significantly higher bio-accessibility (41.26 ± 1.34 %) of curcumin in Pickering emulsions stabilized with CWCS-9%OSA than in the bulk oil system (19.53 ± 1.62 %). This study highlights the potential of chemically modified amphiphilic starch from an underutilized variety of CWCS (Eleocharis tuberosa) to produce the stabilized Pickering emulsion gels as a stable and effective carrier for unstable hydrophobic polyphenolic compounds by enhancing their bioavailability in the foods and pharmaceutics.