Bulk and interface properties determine the thermal stability of potato- and faba protein-stabilized emulsions

: Although plant proteins have been successfully used as emulsifiers in plant-based emulsions, their thermal behavior is not well understood. Particularly the link between bulk, interface, and emulsion stability require clarification. This study examined potato proteins (POPI-200, POPI-300) and faba bean protein (FPI) to evaluate how temperature (20–95 °C) affects bulk gelation, interfacial rheology, and the stability of 45 wt% oil-in-water emulsions at pH 4 and 7 (with/without NaCl). At pH 4, POPI-200 and POPI-300 gelled at 59 and 67 °C, respectively, while FPI showed no gelation. Cooling increased viscosity and storage modulus for all proteins near their isoelectric point. At the interface, POPIs formed more elastic films than FPI at pH 4 and 20 °C, with elasticity decreasing upon heating. All interfaces behaved similarly at pH 7. POPI-stabilized emulsions were initially stable at 20 °C due to high interfacial elasticity, whereas at higher temperatures, increased bulk viscosity dominated stability. Heating induced droplet aggregation and increased surface load, but droplet size remained stable over five days. POPI-200 emulsions showed minimal aggregation and high viscosity, highlighting the importance of bulk properties in thermal stability. These findings clarify plant protein functionality after heating and support the design of thermally stable food emulsions.