Construction of a Rice Glutelin-Rhamnolipid-Pectin Nanoparticle Delivery System for Curcumin Delivery: Effect of Pectin Esterification on Characterization, Stability, and Bioaccessibility

Riceglutelin (RG)-rhamnolipids (Rha)-high-methoxyl pectin (HMP)/medium-methoxy pectin (MMP)/low-methoxy pectin (LMP) were used to attract self-assembled nanoparticles by electrostatic attraction, and the effects of pectin esterification degree and concentration on the characteristics of nanoparticles and the bioavailability of curcumin were evaluated. The minimum particle size and the highest encapsulation efficiency of the nanoparticles were at mass ratios of RG:HMP = 2:1, RG:MMP = 4:1, and RG:LMP = 2:1. The results of Fourier transform infrared spectroscopy and circular dichroism spectroscopy show that hydrogen bonding, hydrophobic interaction, and electrostatic attraction are the main driving forces for the formation of complexes. The X-ray diffraction results verified that the curcumin in the complex was in an amorphous state. In addition, curcumin embedded with nanoparticles has good photothermal and storage stability. The results of in vitro simulated digestion showed that nanoparticles constructed from LMP had high bioaccessibility. The results of this study are expected to provide new ideas for improving the bioaccessibility of curcumin.