Thermization
Encyclopedia
Thermization, also spelled thermisation, is a method of sterilizing
raw milk
with heat. The process is not used on other food products, and is similar to pasteurization
but uses lower temperatures, allowing the milk product to retain more of its original taste. In Europe, there is a distinction between cheeses made of thermized milk and raw-milk cheeses. However, the United States' Food and Drug Administration
(FDA) places the same regulations on all unpasteurized cheeses. As a result, cheeses from thermized milk must be aged for 60 days or more before being sold in the United States, the same restriction placed on raw-milk cheeses by the FDA.
Thermization involves heating milk at temperatures of around 145–149 °F (62.8–65 C) for 15 seconds, while pasteurization involves heating milk at 160 °F (71.1 °C) for 15 seconds or at 145 °F (62.8 °C) for 30 minutes. Thermization is used to extend the keeping quality of raw milk (the length of time that milk is suitable for consumption) when it cannot be immediately used in other products, such as cheese. Thermization can also be used to extend the storage life of fermented milk products
by inactivating microorganisms in the product.
Thermization inactivates psychrotrophic bacteria
in milk, preventing the growth of heat-resistant enzyme
s and allowing the milk to be stored below 8 °C (46.4 °F) for three days, or stored at 0–1 °C (32–33.8 F) for seven days. Later, the milk may be given stronger heat treatment to be preserved longer. Cooling thermized milk before reheating it is necessary for the destruction of bacterial spores. When the milk is first heated, spores begin to germinate, but their growth is halted when the milk is refrigerated. The resulting vegetative bacteria are easier to kill with another heat treatment than the original spores.
Sterilization (microbiology)
Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media...
raw milk
Raw milk
Raw milk is milk that has not been pasteurized or homogenized.-History:Humans consumed raw milk exclusively prior to the industrial revolution and the invention of the pasteurization process in 1864. During the industrial revolution large populations congregated into urban areas detached from the...
with heat. The process is not used on other food products, and is similar to pasteurization
Pasteurization
Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...
but uses lower temperatures, allowing the milk product to retain more of its original taste. In Europe, there is a distinction between cheeses made of thermized milk and raw-milk cheeses. However, the United States' Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA) places the same regulations on all unpasteurized cheeses. As a result, cheeses from thermized milk must be aged for 60 days or more before being sold in the United States, the same restriction placed on raw-milk cheeses by the FDA.
Thermization involves heating milk at temperatures of around 145–149 °F (62.8–65 C) for 15 seconds, while pasteurization involves heating milk at 160 °F (71.1 °C) for 15 seconds or at 145 °F (62.8 °C) for 30 minutes. Thermization is used to extend the keeping quality of raw milk (the length of time that milk is suitable for consumption) when it cannot be immediately used in other products, such as cheese. Thermization can also be used to extend the storage life of fermented milk products
Fermented milk products
Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria such as Lactobacillus, Lactococcus, and Leuconostoc...
by inactivating microorganisms in the product.
Thermization inactivates psychrotrophic bacteria
Psychrotrophic bacteria
Psychrotrophic bacteria are bacteria that are capable of surviving or even thriving in a cold environment. They can be found in soils, in surface and deep sea waters, in Antarctic ecosystems, and in foods....
in milk, preventing the growth of heat-resistant enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s and allowing the milk to be stored below 8 °C (46.4 °F) for three days, or stored at 0–1 °C (32–33.8 F) for seven days. Later, the milk may be given stronger heat treatment to be preserved longer. Cooling thermized milk before reheating it is necessary for the destruction of bacterial spores. When the milk is first heated, spores begin to germinate, but their growth is halted when the milk is refrigerated. The resulting vegetative bacteria are easier to kill with another heat treatment than the original spores.