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Unformatted text preview: Although pasteurization is used to lower the bacterial content of milk and dairy products, it does not achieve sterilization. The conditions of pasteurization are set up to eliminate the tuberculosis bacillus and the rickettsia that causes Q fever. Milk is pasteurized for 30 minutes at about 62C or for 15 to 17 seconds at about 72C. The first method is known as the holding method, the second method as the flash method. Dairy products can be pasteurized at 82C for three seconds, a process known as ultrapasteurization. An alternative heating method is tyndallization, also called intermittent sterilization. Liquids and other items are subjected to free-flowing steam for 30 minutes on each of three successive days. During the first day, all vegetating microorganisms, except spores, are killed. In the overnight period, the spores germinate, and they are killed by the steam on the second day. The last few remaining spores spores germinate, and they are killed by the steam on the second day....
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- Fall '07