Heat treatment of liquid ultrafiltration concentrate influences the physical and functional properties of milk protein concentrate powders

Liquid milk protein concentrate (MPC; 18.3 and 16.5%, w/w, total solids and protein, respectively) was heat treated at 80 °C (low-heat), 100 °C (medium-heat) and 120 °C (high-heat) for 30 s, or did not undergo heat treatment (control), prior to spray drying. Viscosity of the liquid MPC increased with increasing heat treatment temperature. Physical properties of MPC powders were influenced by heat treatment, with the size of powder particles generally increasing with increasing temperature. Heat treatment of ultrafiltration concentrate influenced the heat stability of MPC powders, with high-heat treated MPC having highest heat stability at pH 6.9 and 7.0 (140 °C). However, particle size distribution profiles showed a decrease in powder dispersion with increased heat treatment temperature. This study demonstrated that heat treatment of ultrafiltration concentrate at temperatures ≥100 °C can present challenges with solubilising subsequent MPC powders.