Ultrasonic processing of dairy systems in large scale reactors

Bogdan Zisu, Raman Bhaskaracharya, Sandra Kentish, Muthupandian Ashokkumar

Research output: Contribution to journalArticlepeer-review

175 Citations (Scopus)


High intensity low frequency ultrasound was used to process dairy ingredients to improve functional properties. Based on a number of lab-scale experiments, several experimental parameters were optimised for processing large volumes of whey and casein-based dairy systems in pilot scale ultrasonic reactors. A continuous sonication process at 20 kHz capable of delivering up to 4 kW of power with a flow-through reactor design was used to treat dairy ingredients at flow rates ranging from 200 to 6000 mL/min. Dairy ingredients treated by ultrasound included reconstituted whey protein concentrate (WPC), whey protein and milk protein retentates and calcium caseinate. The sonication of solutions with a contact time of less than 1 min and up to 2.4 min led to a significant reduction in the viscosity of materials containing 18% to 54% (w/w) solids. The viscosity of aqueous dairy ingredients treated with ultrasound was reduced by between 6% and 50% depending greatly on the composition, processing history, acoustic power and contact time. A notable improvement in the gel strength of sonicated and heat coagulated dairy systems was also observed. When sonication was combined with a pre-heat treatment of 80 °C for 1 min or 85 °C for 30 s, the heat stability of the dairy ingredients containing whey proteins was significantly improved. The effect of sonication was attributed mainly to physical forces generated through acoustic cavitation as supported by particle size reduction in response to sonication. As a result, the gelling properties and heat stability aspects of sonicated dairy ingredients were maintained after spray drying and reconstitution. Overall, the sonication procedure for processing dairy systems may be used to improve process efficiency, improve throughput and develop value added ingredients with the potential to deliver economical benefits to the dairy industry.

Original languageEnglish
Pages (from-to)1075-1081
Number of pages7
JournalUltrasonics Sonochemistry
Issue number6
Publication statusPublished - Aug 2010
Externally publishedYes


  • Dairy ingredients
  • Heat stability
  • Particle size
  • Ultrasound
  • Viscosity
  • Whey proteins

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Radiology Nuclear Medicine and imaging
  • Inorganic Chemistry
  • Acoustics and Ultrasonics
  • Environmental Chemistry
  • Organic Chemistry


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