β‐Lactoglobulin Stabilized Emulsions: A Small Angle X‐Ray Scattering Study on Stability, Ageing, and Thermal Effects

ABSTRACT β‐lactoglobulin (BLG) proteins from bovine milk have been widely studied as effective natural stabilizers due to their amphiphilic nature that helps to reduce surface tension. The present work investigates BLG‐stabilized oil‐in‐water emulsions (BLG‐emulsions [BLGem]) at pH 7, focusing on the effects of protein, oil, and salt concentrations under three different conditions (fresh, aged, and aged at elevated temperature). Alongside methods to study emulsions such as optical microscopy, rheology, and dynamic light scattering, we employ synchrotron‐based small‐angle x‐ray scattering (SAXS) and reveal the structural changes in the emulsions over time. We show that higher protein (2–5 wt.%) and higher oil concentrations (40–75 wt.%) improve emulsion stability by reducing the rate of phase separation and coalescence compared to the emulsions with lower protein and oil concentrations and obtain information about how the protein conformation and interface layer thickness varies with the conditions used. Ageing from Days 1 to 90 induce structural changes, including decreased scattering intensity and droplet coalescence. Our studies prove SAXS as an effective tool for studying concentrated systems, giving insights into the structure and behavior of food grade emulsions. Practical Applications : The findings from this study deepen our understanding of protein‐stabilized emulsion systems and the effects of ageing and temperature. The systems studied were designed to replicate real food formulations, characterized by high protein and oil concentrations, aligning with industrial needs for real food products such as creams, sauces, and nutritional beverages. Understanding protein‐stabilized emulsions serves as an important first step toward exploring more complex systems, such as Pickering emulsions.