Pickering emulsions stabilized with β-lactoglobulin nanoparticles studied by small angle X-ray scattering: stability, aging and temperature effects

β-Lactoglobulin (BLG) proteins are widely studied due to their natural abundance, nutritional benefits, and potential to act as effective stabilizers. The present work investigates Pickering emulsions stabilized with nanoparticles made from BLG, focusing on the effect of particle, oil and salt concentrations under different conditions (fresh, aged and aged at elevated temperature). We use small angle and ultra-small angle X-ray scattering (SAXS and USAXS) along with optical microscopy, scanning electron microscopy (SEM), and dynamic light scattering to reveal structural changes over time. We show that higher particle (2-5 wt%) and higher oil concentrations (40-70 wt%) can increase the stability and reduce the rate of phase separation of the emulsion over time. We also show that aging (shelf storage) over a period of 90 days induces different structural changes in the system. Our studies show SAXS to be an effective tool for studying such Pickering-particle based emulsions, giving insights into a system whose structure and behaviour resemble that of food grade emulsions.