the heating of liquids or foods generally to a temperature of 60°-70°C for 15–30 min. In the process, nonspore-forming bacteria are destroyed, but complete sterilization does not result since bacterial spores can withstand such heating. Proposed by L. Pasteur, the method is mainly used to preserve food products that cannot tolerate heating to higher temperatures.
Milk, wine, beer, and other beverages and various foods are pasteurized on an industrial scale. It is recommended that once they are pasteurized, they be kept at a low temperature in order to prevent the germination of bacterial spores.
A related process is fractional sterilization, or tyndallization. After routine pasteurization, the product is cooled and kept for some time at room temperature. When the surviving spores begin to germinate, the product is pasteurized again. Pasteurization is sometimes repeated three or four times.
Milk, cream, juices, and other beverages are pasteurized in centrifugal, tubular, or lamellar pasteurizers. The product is quickly and briefly heated to comparatively high temperatures (up to 100°C) as it continuously flows in a thin layer between the heating surfaces. It is then poured into hermetically sealed containers. Foods that are already bottled or canned are pasteurized by heating with steam while the containers are constantly rotated. Pasteurization of already packaged products using high-frequency sources of heat is a promising development.