Abstract:To improve the quality characteristic of milk protein substrates used in infant formula，membraneseparated milk protein was selected as the research object to investigate the effects of different ultrasonic power and treatment time on milk protein characteristics，which were further verified by spectroscopic analysis.The results demonstrated that ultrasonic modification could enhance the emulsifying properties and surface hydrophobicity of milk protein while reducing particle size，zeta potential，and viscosity.The most significant changes were observed at an ultrasonic power of 300 W，whereas treatment at 600 W led to protein re-aggregation.Milk protein treated with ultrasound at 300 W was subsequently spray-dried，and the solubility of the dried powder was determined.The results showed that ultrasonic treatment significantly improved the solubility of milk protein.Spectroscopic analysis further revealed that the structure of milk protein changed under ultrasonic treatment.In summary，ultrasonic modification increased the emulsifying properties，solubility，and surface hydrophobicity of milk protein，while decreasing particle size，zeta potential，and viscosity，and also altered the structure of milk protein.