Dissolution of milk protein concentrate (MPC) powders by ultrasonication

• MPC powder dissolution rates were compared using stirring and ultrasonication.
• Sonication increases the rate of powder dissolution compared to stirring.
• Sonication is more effective at breaking intermolecular hydrophobic interactions.
• Temperature control must be used during sonication to prevent protein aggregation.

The aim of this study was to determine the effects of ultrasound on the dissolution properties of milk protein concentrate (MPC) powders. A high intensity ultrasound (20 kHz; power 70.2 W) was used to dissolve MPC powder and the dissolution rate was compared to conventional methods of dispersion (e.g., stirring). Rehydration of MPC by stirring at 50 °C complied with the 2-step dissolution model whereby the disappearance of larger particles coincided with the formation of smaller ones over time. MPC dispersal by sonication dramatically accelerated this process, achieving >90% levels of powder solubilisation. Temperature rise (>70 °C) during sonication causes protein denaturation and aggregation, but this can be alleviated using thermal dissipation. Overall, the use of a combination rehydration process for MPC powders involving (i) conventional dissolution (stirring) for 10 min at 50 °C followed by (ii) ultrasonication (<50 °C) for 1 min (energy density 21.1 J/mL) can achieve rapid powder dissolution.