A process in which milk, beer, wine and other liquids are heated to a moderate temperature for a definite period of time in order to destroy microorganisms that would cause spoilage, but without changing to any extent the liquid's chemical composition. In pasteurization of milk, pathogenic bacteria are destroyed by heating at 62 ºC for 30 minutes, or by “flash” heating to 62 ºC for less than 10 to 30 seconds. In Norway, the milk is usually heated to 72 ºC for 15 seconds.
The pasteurization process reduces the bacterial count of the milk by 97% to 99%. It is effective because the common milk-borne pathogens (tubercle bacillus, Salmonella, Streptococcus, and Brucella) do not form spores and are sensitive to heat. Pasteuization was orirginally used in the wine-making industry to prevent living ferments from spoiling the product. The nutritional value of pasteurized milk is not reduced and it can be used for infants.