Microwave-accelerated heating in preparation of pectin nanoparticles cross-linked with Mg²⁺: process optimization and...

Pectin nanoparticles (PNPs) having both pectin and nanomaterials properties, and have been used in food, pharmaceutical and cosmetics formulations for developing products with unique properties. In the present study, PNPs were prepared using ionotropic gelation method and Mg²⁺, as cross-linked ion, under microwave-accelerated heating technique. PNPs in the colloidal form were then lyophilized to prepare PNPs in the powder form. Results indicated that using obtained optimum amount of Mg²⁺ to pectin volume ratio (0.1) and microwave heating time (155 s) using response surface methodology, PNPs with minimum particle size (390 ± 10 nm) and polydispersity index (0.312 ± 0.010) and maximum zeta potential (-23.17 ± 1.5 mV) were produced in the colloidal form. The colloidal form of the PNPs was subjected to lyophilization conditions (pressure and temperature of 100 Pa and - 60 °C, for 48 h) and physico-chemical properties of the prepared PNPs in the powder, were assessed by Fourier transform-infrared spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy and dynamic light scattering methods. Results indicated that the lyophilized PNPs were fabricated in rod shape with amorphous state and smooth surface. Results indicated that by decreasing the concentration of PNPs in the solutions from 1 to 0.01%, viscosity and density also decreased from 1.514 to 1.208 cp. and 1.0045 to 1.0017 g/mL, respectively. Preparation of PNPs as a promising bridge between natural polysaccharides and advanced nanotechnology applications, can explore PNPs role in various formulations and new products.