Formation mechanism and stability of low environment-sensitive ternary nanoparticles based on zein-pea protein-pectin for astaxanthin delivery

This study was devoted for preparing zein-pea protein-pectin ternary nanoparticles through an alcohol-free pH-shifting method for the delivery of astaxanthin (Ax). The complexation of zein and pea protein (PP) in the weight ratio range of 1:2.5 to 1.2:1 maintained the dispersity at pH 7.0 with the average particle size of 90.47–132.38 nm and the polydispersity index of 0.204–0.245. The circular dichroism, fluorescence, Fourier transform infrared spectroscopy and other analyses indicated that the zein interacted with PP to form a composite structure through the folding action of protein structure in the process of pH reduction driven by hydrophobic and electrostatic forces. The incorporation of pectin (pec) further enhanced the physicochemical stability of the nanoparticles. The optimal weight ratio of zein/PP/pec was 2:4:3, and the encapsulation efficiency of astaxanthin reached 94.22%. The X-ray diffraction results showed that the astaxanthin was amorphous after embedding. Compared with Ax/zein-PP, the Ax/zein-PP-pec showed better colloidal stability under the conditions of wide pH range (4.0–8.0), high temperature (90 °C), long time ultraviolet light treatment, and 15-day storage. These results indicated that the construction of the zein-PP-pec nanoparticles could be used as a low environment-sensitive nanocarrier for the loading, protection, and delivery of hydrophobic functional substances such as astaxanthin. [Display omitted] •A novel zein-PP hydrophilic complex protein was prepared by pH-shifting.•Structural changes driven by hydrophobic and electrostatic forces promoted complex protein formation.•Astaxanthin was encapsulated in zein-PP-based nanoparticles with high EE.•Ax/zein-PP-pec nanoparticles exhibited excellent environmental stability.