High temperature short time treatment of raw milk

High temperature short time (HTST) pasteurization treatment used widely in the food industry, but particularly applied to liquid foods such as raw milk, and fruit juices to reduce substantially the total bacterial count for improved shelf life and to eliminate any pathogens.

Milk is a primary example of pasteurized product. Milk is a pasteurized under three different regimens:
Low temperature, long time (LTLT) (63 °C for 30 minutes)
High temperature, short time (HTST) (72 °C for 15 seconds)
Ultrahigh temperature (UHT) (135 °C for less than seconds)

These temperatures ensure the destruction of the most heat-resistant pathogen in milk, Coxiella burnetti, the bacterium that causes Q fever.

The higher the temperature is, the shorter the process time required to pasteurize the milk. HTST pasteurization of raw milk employs a temperature of at least 72 °C for at least 15 sec. This is equivalent on bacterial destruction to the batch method.

The benefit of the HTST regimen is that there is equal or better killing of bacteria with considerably less nutrient loss. A 10 °C change in process temperature produces about a tenfold increase in bacteria kill.

In the HTST pasteurization raw milk held in a cool storage tank is pumped through a plate-type heat exchanger and brought to temperature. The key to the process rests in ensuring that every particle of the milk remains at not lower than 72 °C for no less than 15 sec.

This is accomplished by pumping the heated milk through a holding tube of such length and diameter that it takes every milk particle at least 15 sec to pass through the tube.

In the High Temperature Short Time process treatment has little effect on nutrients but there is a 20% loss of vitamin C. Shelf life is increased to a few days.
High temperature short time treatment of raw milk