Granular hydrogels with tunable properties prepared from gum Arabic and protein microgels

Granular hydrogels have emerged as a new class of materials for 3D printing, tissue engineering, and food applications due to their extrudability, porosity, and modularity. This work introduces a convenient method to prepare granular hydrogel with tunable properties by modulating the interaction between gum Arabic (GA) and whey protein isolate (WPI) microgels. As the concentration of GA increased, the appearance of the hydrogel changed from fluid liquid to moldable solid, and the microstructure changed from a macro-porous structure with thin walls to a dense structure formed by the accumulation of spherical particles. At a GA concentration of 0.5 %, the hydrogels remained fluid. Granular hydrogels containing 1.0 % GA showed mechanical properties similar to those of tofu (compressive strength: 10.8 ± 0.5 kPa, Young's modulus: 16.7 ± 0.4 kPa), while granular hydrogels containing 1.5 % GA showed mechanical properties similar to those of hawthorn sticks and sausages (compressive strength: 300.4 ± 5.8 kPa; Young's modulus: 200.5 ± 3.4 kPa). The hydrogel with 2.0 % GA was similar to hawthorn sticks, with satisfactory bite resistance and elasticity. Such tunability has led to various application potentials in the food industry to meet consumer demand for healthy, nutritious, and diverse textures.