The Effect of pH on Coalescence Stability of Potato Protein Stabilized Droplets Analyzed at Microsecond Time Scale Using Microfluidic Techniques

Plant‐based proteins, such as those derived from potatoes, are increasingly used to stabilize oil‐in‐water (O/W) emulsions due to their higher sustainability. Their interfacial activity is strongly influenced by their structure. Given the sub‐millisecond timescales at which emulsion droplets are generated at large scale, this activity would need to be measured within this time range to be in a position to connect to eventual emulsion stability. This necessitates dedicated analytical tools. In this study, a custom‐designed microfluidic device was used to investigate the coalescence stability of O/W droplets stabilized by two commercial potato protein fractions, patatin and protease inhibitor, across a range of pH values relevant for food (3–7) and protein concentrations (0.1–1 g/L). Droplet stability was assessed 11 milliseconds after formation and shows a strong pH dependence. Both patatin and protease inhibitor exhibited high interfacial stabilization near neutral pH, while higher coalescence levels were observed at lower pH. This is correlated with protein secondary structure changes (e.g., α‐helix, β‐sheet content) and surface‐exposed hydrophobicity. This study highlights the utility of this microfluidic technique in capturing early‐stage interfacial phenomena and provides insights into the pH response of plant proteins.