Thermization, also spelled thermisation, is a method of sanitizing

raw milk Raw milk or unpasteurized milk is milk that has not been pasteurized, a process of heating liquid foods to kill pathogens for safe consumption and extending the shelf life. Proponents of raw milk have asserted numerous supposed benefits to consu ...

with low heat. "Thermization is a generic description of a range of subpasteurization heat treatments (57 to 68°C × 10 to 20 s) that markedly reduce the number of spoilage bacteria in milk with minimal heat damage." The process is not used on other food products, and is similar to

pasteurization Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than , to eliminate pathogens and extend shelf life. The ...

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 The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...

(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 for 15 seconds, while pasteurization involves heating milk at for 15 seconds or at 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 or fermented dairy 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'', ''Lactococcu ...

by inactivating microorganisms in the product. Thermization inactivates

psychrotrophic bacteria Psychrophiles or cryophiles (adj. ''psychrophilic'' or ''cryophilic'') are extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from to . They have an optimal growth temperature at . They are found i ...

in milk and allows the milk to be stored below for three days, or stored at for seven days. Later, the milk may be given stronger heat treatment to be preserved longer. Cooling thermized milk before reheating is necessary to delay/prevent the outgrowth of bacterial spores. When the milk is first heated, spores can begin to germinate, but their growth can be halted or delayed when the milk is refrigerated, depending on the microorganisms' growth requirements. Germinated spores are sensitive to subsequent heating, however since germination is not a homogeneous process, not all spores will germinate or be inactivated by subsequent heating.

References

{{food preservation Food preservation