Preparation and properties of the pectic gel microparticles based on the Zn2+, Fe3+ and Al3+ cross-linking cations

Abstract

The aim of this work was to evaluate the relationship between the cross-linking cation content in the microparticles, chemical characteristics of pectins and swelling properties of the gel microparticles based on the Zn²⁺, Fe³⁺ and Al³⁺ cross-linking cations. A significant negative correlation between the Zn²⁺ content and DM of pectin indicated that decreasing DM of pectin promoted Zn²⁺ binding. The microparticles from the pectins with a higher linearity had a higher content of Fe³⁺. The microparticles from the pectins with a lower Mw, branching of rhamnogalacturonan I, amount of RG, specific viscosity and a higher linearity had a higher content of Al³⁺. The content of the Fe³⁺ ions in the microparticles was higher than the Zn²⁺ content. The Al³⁺ content in the microparticles was lowest. The Fe³⁺ and Zn²⁺ ions, which are more electronegative, bind more strongly to pectin in comparison with the less electronegative Al³⁺ cations. The microparticles with a higher Zn²⁺, Fe³⁺, and Al³⁺ content had a lower swelling degree in the simulated digestive fluids. Moreover, the higher swelling of the microparticles can be due to their porous or wrinkled surface. Variation of specific cations and pectins can influence the functionality of the gel microparticles, in particular swelling properties.

Keywords: Cross-linking cation; Pectic gel microparticles; Swelling.