High-Temperature Short-Time

A laboratory scale pasteurizer was built to simulate continuous HTST pasteurization. The system included a peristaltic pump (Watson Marlow 505S, Hudson, MA, USA), as well as a heating, a holding, and a cooling section (Figure 2). All sections were connected to an RS PRO 1,384 temperature data logger. The pump, which ran at a speed of 35 rpm, was connected with a plastic tube (ø 4 mm) to a copper heating coil (810 mm, ø 4 mm), that was fully submerged into a water bath (heating section). A thermocouple was placed at the end of the coil to determine whether the milk (50 mL) leaving the heating section indeed reached a temperature of 72°C. The coil was then connected to a plastic tube (ø 4 mm) that remained submerged into a second water bath (holding section, 15 sec). A second thermocouple was placed at the end of the holding section. The milk passed then through a copper coil (1,395 mm, ø 4 mm) which was submerged in an ice-water bath (2°C). Finally, a third thermocouple was linked with the coil to monitor the temperature at the end of the cooling phase. The cooled milk was then dispensed into a sterile bottle (Beldico SA, Marche-en-Famenne, BE).

Schematic representation of the HTST system set-up.