Design and characterization of calcium-pea protein fluid gels

Fluid gels have gained increasing attention due to their distinctive rheological properties and techno-functional properties. However, for plant protein based-systems,the gelling mechanism under shear and the resulting physical behavior remain unexplored. To address this gap, we fabricated calcium-pea protein fluid gels and investigated the influence of protein concentration (10-15% w/w), calcium ion concentration (10-50 mM), and shear rate (300-1000 s -1 ) on particle morphology, rheological behaviors, and aging properties. Results demonstrated that increasing protein concentration enhanced both the effective volume fraction and intrinsic storage modulus of individual microgel particles, thereby strengthening the elastic response of the fluid gel network. A similar trend was observed with calcium concentrations between 10–20 mM. However, above 50 mM, particle compaction and structural heterogeneity reduced volume occupancy and lowered the elastic modulus of gels. At lower production shear rates, Ca–pea protein fluid gels exhibited large particles with highly frictional irregular shapes, which concentrate large local stresses and deformation, thereby reducing the resistance to large deformations. Conversely, increasing the shear rate during gel preparation led to the formation of smaller and rounder particles, allowing for more uniform stress distribution and a greater resistance to deformation prior to yielding. In contrast with the case of dispersions prepared at lower rates, repeated intermittent shear led to mechanical stabilization, leaving lower capacity for further network reorganization, which reflected in different aging exponents. These findings provide a valuable foundation for further scientific investigations and facilitate the engineering and application development of plant protein-based fluid gels. • Fluid gels of controlled rheological properties were generated based on pea protein • Particle elasticity, determined by % protein or Ca 2+ , affects fluid gel rheology • Low shear forms rougher particles while rounder shapes arise from high shear • Pea protein fluid gels show physical ageing and shear history dependency