Zisu et al. [37] used ultrasonic frequency of 20 kHz at
power of 40–80W to reduce viscosity of concentrated
milk. They observed that sonication lowered the viscosity
of skim milk, and once sonication applied, prevented the
viscosity of skim milk concentrates from increasing rapidly.
Furthermore, the authors concluded sonication has
industrial application potential for spray drying by
decreasing the viscosity of concentrated milk. Recently,
Yanjun et al.