OSA-modification rice, debranched, and soluble starches encapsulating ferulic acid: interfacial effects and enhanced solubility, stability, bioactivity, and sustained release.

Ferulic acid (FA) is a natural polyphenolic compound that has garnered significant attention due to its exceptional antioxidant, anti-inflammatory, and anticancer bioactivities. However, its poor chemical stability, low solubility, and insufficient bioavailability in practical applications severely limit its widespread use in the food, pharmaceutical, and cosmetics industries. To improve the stability and bioavailability of FA, this study used rice starch (RS), debranched starch (DBS) and soluble starch (SS) modified with octenyl succinic anhydride (OSA) as carriers to prepare three FA complexes, with the aim of improving their solubility and stability. The antioxidant activity, stability, and in vitro release behavior of the encapsulated FA were evaluated. Experimental results indicated that the encapsulation mechanism of ferulic acid by starch-based carriers involves hydrogen bonding, van der Waals force, and hydrophobic interactions. OSA-DBS exhibited the highest encapsulation efficiency, attributed to its compact cavity spiral structure. At the same time, OSA-SS and OSA-RS had lower encapsulation efficiencies due to their loose structure and mixed crystalline-amorphous structure, respectively. FA@OSA-DBS exhibited the strongest antioxidant activity and antibacterial ability, with significantly improved solubility and stability. In vitro release studies showed that FA@OSA-DBS exhibited a slow release rate in a simulated physiological environment, following a first-order kinetic model. The results indicate that the preparation of FA complexes using esterified starch can significantly improve the physical and chemical properties of FA by regulating the interfacial characteristics of starch. This finding lays the theoretical foundation for the development of phenolic acid-starch composite systems in the field of functional materials.