Preparation and characterization of zein-pectin based nanoparticles and its protective efficacy in probiotic microencapsulation during gastrointestinal digestion.

The objective of this research was to characterize zein-pectin based nanoparticles (ZNP-P) prepared by synergistic methodology of antisolvent precipitation and complex aggregation, and investigate its protective efficacy for probiotic microencapsulation during simulated gastrointestinal digestion. Nanoparticles were successfully fabricated by zein and pectin primarily through electrostatic, hydrophobic and hydrogen bonding interactions, resulting in more compact nanoparticle structures with increased particle size. Multi-spectroscopic analysis indicated that the incorporation of pectin induced a significant conformational transition in zein with the content of unordered coil and β-strand structure increasing and that of α-helix structure decreasing, as well as static quenching that facilitated the binding of pectin molecules to tyrosine residue ligands and ultimately promoted the rapid de-excitation of α-zein. Simulated gastrointestinal digestion analysis manifested that after encapsulating with probiotics, uniform and compact coating layers composed of ZNP-P nanoparticles were formed and with the increasing incorporation of pectin, interparticle voids between ZNP nanoparticles were further filled leading to the formation of a densely packed three-dimensional network that significantly improved the acid resistance of encapsulated probiotics during gastric digestion. In summary, the current study proved that ZNP-P nanoparticles-based probiotic microcapsules with high structural density can provide better protection against adverse gastrointestinal digestion environments.