Protein-Polysaccharide Hydrogel Particles Formed by Biopolymer Phase Separation

Abstract

Biopolymer-based hydrogel particles were fabricated using a segregation-aggregation phase separation mechanism. Pectin-coated whey protein isolate (WPI) hydrogel particles (d ~ 2 μm) were formed when solutions of heat-denatured (90 °C/10 min) WPI (1.5 %) and pectin (1.5 %) were mixed at pH 7, and then adjusted to pH 5 with constant stirring. Hydrogel particle properties and suspension appearance were strongly influenced by pH (2 to 8) and calcium chloride (0–5 mM) due to the importance of electrostatic interactions. At pH 2 to 3, extensive biopolymer complexation occurred leading to highly viscous solutions. At pH 6 to 8, biopolymer complexes disintegrated due to weakening of electrostatic attraction leading to clear solutions. Calcium addition promoted biopolymer aggregation and an increase in viscosity. All systems containing intact hydrogel particles had a whitish appearance similar to that of milk. These biopolymer-based hydrogel particles may be suitable as texture modifiers, fat replacers, or delivery systems for utilization in foods.