Food-Grade Pickering Emulsions Stabilized by Ultrasound-Treated Foxtail Millet Prolamin: Characterization and In Vitro Release Behavior of Curcumin

To date, extensive studies have focused on developing proteins as stabilizers to fabricate food-grade emulsions for encapsulating bioactive compounds aimed at targeted delivery. This paper aimed to develop a novel stabilizer using foxtail millet prolamin (FMP) to fabricate medium internal-phase Pickering emulsions (MIPEs) and investigate the stability and <i>in vitro</i> release behavior of curcumin (Cur) encapsulated within the MIPEs. Ultrasound treatment modified the secondary and tertiary structures of FMP, along with its particle size, zeta potential, and wettability, enhancing its functionality as a stabilizer for MIPEs. The MIPEs stabilized by 65% ultrasound-treated FMP (FMP-U) exhibited better rheological properties and stability, significantly improving the storage stability and antioxidant activity of Cur. <i>In vitro</i> digestion results demonstrated that the MIPEs delayed the release of Cur, achieving a final release rate of 84.0 ± 1.47% after 4 h of gastrointestinal digestion and the DPPH radical scavenging activity (RSA) of 39.9 ± 1.31%, which was notably higher than the RSA of free Cur in oil at only 5.8 ± 1.37%. Moreover, MIPEs with Cur increased the bioaccessibility of Cur. This study provides new insights into a novel delivery system designed with FMP-U for encapsulating hydrophobic compounds, thereby enhancing their stability, sustained release, and bioaccessibility.