A novel pectin from Akebia trifoliata var. australis fruit peel and its use as a wall-material to coat curcumin-loaded zein nanoparticle

In this study, a pectin was extracted from Akebia trifoliata var. australis fruit peel waste using water solution, and its physicochemical properties were evaluated. The pectin was rich in galacturonic acid (GalA) content (76.68%). The degree of esterification (DE) and molecular weight (Mw) were 37.60% and 29,890 Da, respectively. The pectin structure was determined using Fourier transform-infrared (FT-IR) and Hydrogen nuclear magnetic resonance (H-NMR). The pectin exhibited an amorphous nature, negative charge, and good solubility. The pectin was then used as a wall-material to coat curcumin-loaded zein nanoparticles for the first time. The obtained nanoparticles (curcumin-loaded core-shell nanoparticle, CLCSNs) exhibited a core (zein)-shell (pectin) structure and a spherical shape with an average diameter of 230 nm. The electrostatic attraction, hydrogen bonding, and intermolecular interaction were involved in the CLCSNs formation. A high encapsulation efficiency (EE, 89.65%) and loading capacity (LC, 10.35%) of the CLCSNs were obtained for the curcumin. The solubility, stability, antioxidant activity, and in vitro bioavailability of the curcumin were significantly increased after loading into the CLCSNs. Therefore, this sustainable pectin from Akebia trifoliata var. australis fruit peel waste represents a promising natural macromolecule for use in the pharmaceutical and food industries.