Polyelectrolyte Properties of Citrus Pectins and Their Influence on Oil-in-Water Emulsions

High methoxy citrus pectin can essentially be regarded as a polyelectrolyte. As a result it shows particular solution properties due to decreased electrostatic interactions upon pH reduction. We can show that the resulting decrease in charge and hydrodynamic radius leads to larger effective diffusion coefficients to the oil-water interface. The corresponding high pressurized oil-in-water emulsions show smaller characteristic droplet sizes d_90,3 when produced from pectins with a high degree of esterification and at low pH. Despite differences in droplet size distributions, only minor differences in viscosity and viscoelasticity could be observed for emulsions of 30 vol.-% disperse phase. This offers the possibility to use such pectins in products where different emulsion microstructures but comparable rheological properties are needed.