Interfacial behavior of oat protein hydrolysates and its regulatory mechanism on emulsion stability

This study investigates how enzymatic hydrolysis affects oat protein hydrolysate structure and relates these changes to oil-in-water emulsion stability. Interfacial behavior was characterized by surface tension, adsorption kinetics, interfacial protein content, and adsorption rate. Results show that moderate hydrolysis at enzyme-to-substrate ratios (E/S) of 0.125%-0.50% shifts the droplet size to smaller values, increases ζ-potential, and reduces the Turbiscan stability index (TSI). Optimal stability occurs at E/S of 0.25% and 0.50%, while higher concentrations (E/S ≥ 1.00%) cause aggregation and decreased stability. Interfacial analysis reveals that at 0.25% E/S, oat protein exhibits favorable diffusion and adsorption rates, higher interfacial protein content, and thicker interfacial films. At 0.50% E/S, a significant increase in rearrangement rate, along with decreased protein content and adsorption rate, leads to a more densely rearranged interfacial film. Thus, protein structural characteristics such as molecular weight dictate distinct interfacial layer properties at the oil-water interface.