Research background. The application of high power ultrasound, combined with a slightly increased temperature on raw whole cow milk, skimmed cow milk, and skimmed cow milk that passed the bactofugation process were analyzed. A combination of those techniques, ultrasound and the bactofugation of milk was conducted to achieve the microbiological accuracy that is usually achieved by the pasteurization process.
Experimental approach. The milk samples (200 mL) were treated for 2.5, 5, 7.5 and 10 minutes with high-power ultrasound (200 W and 400 W) with a frequency of 24 kHz. The treatments were conducted with a constant duty cycle of 100 %. Temperature levels during the treatments were 20 °C, and 55 °C. The count of somatic cells was analyzed for the aerobic mesophilic bacteria, as well the number of Enterobacteriaceae, Escherichia coli, and Staphylococcus aureus cells.
Results and conclusions. The best result from the perspective of the reduction of the total count of bacteria was achieved by high-power ultrasound with a power of 400 W treated for 10 minutes. High reduction of Enterobacteriaceae, E. coli, and S. aureus cells was achieved in ultrasound treatment of raw whole, skimmed, and skimmed cow milk with a power of 200 and 400 W regardless of a treatment time.
Novelty and scientific contribution: High-power ultrasound with a combination of bactofugation as a pretreatment for milk and with a slightly increased temperature (up to 55 °C) is much more economical than the pasteurization process, while it preserves the sensory and physical-chemical properties of milk.
The Influence of High-Power Ultrasound and Bactofugation on Microbiological Quality of Milk
