Improving heat stability and foam stability using mesoscale whey protein aggregates manufactured through an antisolvent-based method

This study investigated the physicochemical, interfacial, foaming and emulsifying properties of mesoscale whey protein aggregates (mWPA) produced through a scalable method involving liquid antisolvent (LAS) precipitation, heat treatment and microfluidization. These properties of mWPA were compared with two types control samples (1) untreated whey protein isolate (WPI) and (2) conventional whey protein aggregates (cWPA) induced by heat treatment. The mWPA exhibited more compact, spherical morphologies with particle size of ∼197 nm. These are distinct from cWPA and WPI, in which the former possessed a more fractal morphology with a smaller mean particle size (∼70 nm); while the latter had a spherical morphology but its mean particle size was significantly smaller. Physicochemical characterizations demonstrated that mWPA possessed higher surface hydrophobicity, higher surface charge, and improved colloidal stability after heating at 90 °C for 30 min compared to WPI. mWPA showed initial adsorption kinetics comparable to WPI at low protein concentrations ( 0.025-0.25%, wt/vol), but a lower equilibrium surface pressure at a high (1%, wt/vol), as revealed by dynamic adsorption measurements. This suggests restricted interfacial rearrangement and limited continuous adsorption for mWPA at the air-water interface. The foaming capacity of mWPA is comparable to WPI and cWPA, but it showed a superior foam stability, which was attributed to (1) stiffer interfacial films formed at lower (0.025%-0.05%, wt/vol) as evidenced by higher values obtained in dilatational rheology experiments, and (2) physical entrapment of particles within lamellae and Plateau borders at a higher (1%, wt/vol). In oil-in-water model emulsions, mWPA exhibited higher emulsifying activity than WPI but led to pronounced droplet flocculation and reduced emulsion stability with persistent flocculation, progressive coalescence and creaming during ambient storage. This study successfully demonstrated a scalable and distinctive method for modifying WPI, resulting in a protein colloidal particle with enhanced heat and foam stability.