Effects of different ultrasonic treatments on the physicochemical and solubility properties of milk protein concentrate aggregates

Background Milk protein concentrate serves as an ideal ingredient in food and nutritional products due to digestibility. But it is prone to deterioration of solubility during storage. It is necessary to understand the effects of different ultrasonic treatments on the physicochemical and solubility properties of milk protein concentrate aggregates. Aim(s) This study aimed to investigate the effects of different ultrasonic treatments on the physicochemical and functional properties of insoluble milk protein concentrates (MPC). Methods MPC solution was treated by water bath ultrasound and probe ultrasound (100, 300, 500 W), respectively. These samples were used to determine the SDS‐PAGE, FTIR, particle size, scanning electron microscopy and solubility. Major Findings SDS‐PAGE results indicate that the low‐molecular‐weight (10 kDa) band darkened following treatment, suggesting that ultrasonication facilitates the dissociation of macromolecular noncovalent aggregates. FTIR demonstrated that ultrasonication altered the secondary structure of MPC. Additionally, ultrasonication reduced the particle size of MPC aggregates. Probe ultrasonication notably improved solubility, increasing it from 39% to 94% after treatment at 100 W. Scientific or Industrial Implications The results revealed that ultrasonic treatment improved the solubility of MPC. However, a significant difference was noted between the effects of water bath and probe sonication treatments. Water bath ultrasonication was particularly effective. These findings provide a theoretical foundation for effectively enhancing the functional properties of MPC and expanding its application in the food industry.