Wheat gluten stabilized emulsions: Influence of homogenization process, pH, and ethanol concentration on droplet breakup and stabilization

Abstract

Wheat gluten's use as an emulsifier in vegetarian products is limited by insufficient understanding of its emulsifying properties. We prepared d-limonene based oil-in-water-emulsions with varying formulation and process parameters to elucidate its stabilizing mechanism.Gluten's emulsifying properties depend on the total gluten concentration in solution, which is influenced by pH. Low solubility can be compensated by dispersing a larger amount of gluten into the solution.Ethanol does not influence gluten solubility but enhances droplet breakup by reducing the interfacial tension between oil and aqueous phase. Consequently, in high-pressure homogenized emulsions, droplet sizes increased because gluten's adsorption kinetics were too slow to stabilize the amount of newly created interface resulting in recoalescence. Gluten hydrolyzation reduced the preferentially adsorbing large molecular weight fractions resulting in decreased steric stabilization.These findings indicate that the individual protein fractions might require targeted modifications to improve their solubility and adsorption kinetics.