Dual-modified starch as particulate emulsifier for Pickering emulsion: Structure, safety properties, and application for encapsulating curcumin.

In this study, cinnamic acid modified acid-ethanol hydrolyzed starch (CAES) with different degrees of substitution (DS) was fabricated to stabilize Pickering emulsions and probed their application for encapsulating curcumin (Cur). Successful preparation of CAES (with DS from 0.016 to 0.191) was confirmed by 1H NMR and FT-IR, and their physicochemical properties were characterized by XRD, SEM, and TGA. The biosafety evaluations and surface wettability confirmed the excellent safety and amphiphilic character of CAES. CAES-stabilized Pickering emulsion (CS-PE) exhibited different emulsion stability at different DS, with CS-PE (0.031) showing the highest stability. CLSM revealed that the CAES (0.031) formed a dense barrier on the surface of the oil droplets, preventing them from coalescing. The CS-PE (0.031) achieved effective encapsulation of Cur (up to 96.2 %). Compared with free Cur, CS-PE (0.031) exhibited better photochemical stability, higher free fatty acids (FFA) release, and enhanced bioaccessibility. These studies suggested that CAES may serve as a promising emulsifier for stabilizing Pickering emulsions to encapsulate and deliver hydrophobic bioactive compounds.

Efficient encapsulation of fat-soluble food-derived biofunctional substances (curcumin as an example) in dual-modified starch-based nanoparticles containing large conjugated systems.

Acid-ethanol hydrolysis and subsequent cinnamic acid (CA) esterification were employed to prepare a series of dual-modified starches efficiently loaded with curcumin (Cur) utilizing large conjugation systems provided by CA. Structures of the dual-modified starches were confirmed by IR and NMR, and their physicochemical properties were characterized by SEM, XRD and TGA. The nanoparticles fabricated from the dual-modified starch have perfect spherical shape (250.7-448.5 nm, polydispersity index <0.3), excellent biosafety (no hematotoxicity, no cytotoxicity, no mutagenicity) and high loading of Cur (up to 26.7 % loading). By XPS analysis, this high loading was believed to be supported by the synergistic effect of hydrogen bonding (provided by hydroxyl groups) and π-π interactions (provided by large conjugation system). In addition, the encapsulation of dual-modified starch nanoparticles effectively enhanced the water solubility (18-fold) and physical stability (6-8-fold) of free Cur. In vitro gastrointestinal release showed that Cur-encapsulated dual-modified starch nanoparticles were released more preferably than free Cur and that the Korsmeyer-Peppas model was the most suitable release model. These studies suggest that dual-modified starches containing large conjugation systems would be a better alternative for encapsulating fat-soluble food-derived biofunctional substances in functional food and pharmaceutical applications.

Dual-modified starch nanoparticles containing aromatic systems with highly efficient encapsulation of curcumin and their antibacterial applications.

A series of cinnamic acid (CA)-esterified debranched starch (CDS) containing aromatic systems were prepared and successfully fabricated as nanoparticles to encapsulate curcumin by taking advantage of the additional π-π interactions provided from CA. The CDS nanoparticles (CDS NPs) have good dispersion (polydispersity index of 0.124-0.314) and sizes range of 130-330 nm. The excellent biosafety of CDS NPs was demonstrated by hemolysis, cytotoxicity and mutagenicity assays. Efficient encapsulation (LC = 26.86 %) and sustained release of curcumin were achieved, and the curcumin-encapsulated CDS NPs (CDS-Cur NPs) increased 266-fold water solubility and 2.3-6.5-fold photothermal stability for curcumin, compared to free curcumin. Functional studies showed that CDS-Cur NPs exhibited superior biofilm scavenging ability, with a 2-4.3-fold improvement compared to free curcumin. In addition, CDS-Cur NPs also exhibited far superior antibacterial effects than free curcumin in a bacteriostatic food model of chicken breast. This study not only provides a new scheme for the efficient loading of curcumin, but also provides new ideas for the usage of starch-based materials in antibacterial applications.