The formulated beverage was heated at 90 C (Tin) using a plate heat exchanger before entering the high pressure intensifier, where the temperature (Tcomp) increased due to heat of compression.
Subsequently the fluid was depressurized via two-stage homogenization valves.
At the end of homogenization, the temperature of the beverage increased ~18 C per 100 MPa (Tp) due to dissipation of kinetic energy upon discharging pressure. The length of the pipe that connects the distance between first and the second homogenization stage was considered as the holding tube and it provides a residence time of less than 1 s.
Thus, under such test conditions, the product temperature did not change between first and second homogenization stage. After second homogenization stage, the fluid is cooled to a refrigeration temperature (Tc).
Residence times of 0.24, 0.48 and 0.7 s have been reported in literature for pilot scale HPH units.
It is worth to mention that the demonstration of commercial sterility was not a goal of the current study. However, similar to what is practiced in aseptic processing industry, by adjusting the high pressure homogenization process conditions (initial and process temperature of the beverage, target homogenization pressure), and/or having a hold tube section of adequate length, it may be possible to produce beverages with commercial sterility.