Interfacial and emulsifying behavior of plant-based microgels via complex coacervation

In recent years, rising global protein demand and increasing awareness of sustainability, climate change, and animal welfare issues have accelerated the shift toward plant-based foods. Despite their promise as sustainable animal-protein alternatives, plant proteins are often limited by inherent astringency associated with high friction and poor lubrication. In this work, pH-responsive microgels derived from liquid-liquid phase separation (LLPS) of deamidated β-conglycinin (D-β-CG) and chitosan oligosaccharide (COS) were engineered to modulate interfacial behavior and lubrication in dairy systems. The adsorption dynamics and interfacial structure were strongly modulated by pH-dependent changes in particle size and surface charge. At pH 5, restricted aggregation of D-β-CG/COS microgels led to slower diffusion, lower adsorption rates and earlier yielding under deformation. In contrast, microgels at pH 3 and pH 8 swelled to form hydrated, loose "soft" interfacial layers capable of imparting Pickering-like stabilization. These microgels effectively reduced friction in dairy systems by forming hydrated, deformable interfacial layers that promoted smooth sliding. This study provides insight into LLPS-derived microgel interfacial behavior and offers a strategy to improve lubrication and oral processing in dairy products.