Calcium binding properties of heat-induced pea globulin aggregates

Abstract Pea protein isolates used in protein-rich foods are typically produced by alkaline extraction and isoelectric precipitation and undergo thermal treatments that can modify protein structure, aggregation, and functionality. This study examines the calcium-binding capacity of heat-denatured pea globulins and the colloidal behavior of the resulting calcium–protein complexes. Protein dispersions (~ 2% w/v, pH 7.5) were thermally treated at 70, 80, and 90 ° C and analyzed in comparison to a non-heated control. Thermal properties (µDSC), surface characteristics (Zeta-potential, surface hydrophobicity), aggregation behavior (turbidity, dynamic light scattering, intrinsic viscosity), and the calcium-binding capacity of the soluble pea protein aggregates, were evaluated by progressive Ca 2+ addition (0–20 mM). The denaturation rate increased from 0% to 100% with increasing temperature, leading to higher surface hydrophobicity and a reduced negative charge of the proteins. Calcium-binding of the submicrometric pea protein aggregates via intra-protein association slightly increased compared to unheated protein dispersions. Further Ca 2+ addition (> 6–7 mM) promoted an increase of complex size through inter-protein association for low-denatured proteins (unheated or preheated at 70 ° C), whereas smaller and more compact protein complexes were formed in systems preheated at higher temperatures. In all cases, the addition of calcium led to the formation of insoluble protein aggregates; however, preheated systems formed apparently denser precipitates. These findings provide insights into the mechanisms underlying complex formation between pea protein aggregates and added calcium ions, and may support the development of novel plant-based food formulations with tailored texture, stability, and mineral bioavailability.