Utilization of insect proteins to formulate nutraceutical delivery systems: Encapsulation and release of curcumin using mealworm protein-chitosan nano-complexes

The potential of using insect proteins to encapsulate and protect hydrophobic nutraceuticals within biopolymer nano-complexes was examined. Insect proteins were used to form nanoparticles that were uncoated or coated with chitosan. Initially, the nature of the curcumin-mealworm protein interaction was investigated. Curcumin mainly interacted with the hydrophobic core of the insect protein nanoparticles through hydrophobic forces. About one curcumin molecule bound per protein molecule in both the absence and presence of chitosan. The binding constants (K) were 1.1 × 10⁴ M⁻¹ and 0.7 × 10⁴ M⁻¹ for curcumin loaded in the uncoated and coated nanoparticles, respectively. Differential scanning calorimetry showed increased thermal stability of the proteins after interaction with curcumin or chitosan. Encapsulation efficiency of the curcumin within the biopolymer nano-complexes was 30–47% depending on the system. Transmission electron microscopy and dynamic light scattering analysis showed that the biopolymer nano-complexes were spherical and relatively small (d = 143–178 nm). FTIR suggests that curcumin was stabilized more effectively in the coated nano-complexes, due to non-covalent intermolecular interactions. Curcumin release under oral, gastric, and intestinal conditions showed that over 90% of the nutraceutical was released after exposure to model gastrointestinal conditions. The findings demonstrate the potential of using insect proteins for fabricating colloidal delivery systems for water-insoluble nutraceuticals.