Described are emulsion compositions comprising oil, water and partially hydrolyzed soy beta-conglycinin, as well as materials and methods for their preparation and use. The soy beta-conglycinin can be enzyme-hydrolyzed material, such as trypsinized material. The degree of hydrolysis of the soy beta-conglycinin can be light, for example up to 2.5%. The hydrolyzed soy beta-conglycinin can be effective to form fibril sheets adsorbed to oil droplets at the interface between the droplets and a continuous aqueous phase in an emulsion composition. The soy beta-conglycinin can be hydrolyzed to such an extent that it provides improved oxidative stability to the oil in the emulsion composition while also providing physical stability equal to and/or greater than that obtained using a corresponding nonhydrolyzed soy beta-conglycinin composition.