Physicochemical properties and stability of model sauces stabilized by heat-modified whey protein concentrate...

One current trend in the food industry is replacing traditional emulsifiers and stabilizers with natural alternatives such as dairy proteins. This study investigated the heat-treated whey protein concentrate particles (WPP), prepared from heating and sonicating whey protein concentrate, as Pickering stabilizers for high-oil emulsions at pH 5, mimicking commercial sauce formulations. The effects of protein concentration (3%-5%), oil content (30%-50%), and ionic strength (20-400 mM NaCl or 20 mM CaCl₂) on droplet size, zeta potential, rheological performance, microstructure, storage stability, and thermal stability were systemically evaluated. Increasing protein concentration from 3% to 5% significantly reduced droplet size and enhanced apparent viscosity. Contrary to conventional emulsion behavior, increasing oil content at fixed protein levels generally decreased droplet size when sufficient WPP were available, indicating adequate interfacial coverage. Salt addition reduced zeta potential promoted hydrophobic interactions, and enhanced protein adsorption at the oil-water interface, improving emulsion homogeneity and stability. Formulations containing 200 to 400 mM NaCl, or 20 mM CaCl₂ achieved viscosities comparable to commercial sauces. High-protein and high-oil emulsions (4%-5% protein, 40%-50% oil) exhibited excellent stability after 60 d under ambient temperature. Thermal stability tests revealed that high NaCl concentrations effectively prevented coalescence (volume-weighted mean diameter [D_4,3] ∼6 µm), whereas salt-free formulations showed substantial droplet enlargement (D_4,3 ∼16 µm). Compared with commercial products, optimized WPP-stabilized emulsions demonstrated smaller droplet sizes, comparable stability, and similar viscosity at consumption-relevant shear rates. These findings establish WPP as effective Pickering stabilizers for ingredient-friendly sauce formulations.