Re: What are the two types of milk pasteurization?

Date: Tue Dec 14 09:01:00 1999
Posted By: James S. Dickson, Faculty, Microbiology, Iowa State University
Area of science: Microbiology
ID: 941322476.Mi

Message:

There are actually several variations of milk pasteurization, but all involve the same basic principle. Briefly, milk is heated to a specific temperature for specified period of time.

The common methods of pasteruization are:

Low temperature/long time ("vat") pasteurization: 62.8 C (145F); 30 minutes
High temperature/short time: 71.7 C (161 F) 15 seconds

"Flash" pasteurization can be

89 C (192 F) 1 sec
90 C (194 F) 0.5 sec
94 C (201 F) 0.1 sec
96 C (204 F) 0.05 sec
100 C (212 F) 0.1 sec  
96 C (204 F) 0.05 sec
100 C (212 F) 0.1 sec

UHT (ultra high temperature) milk is actually sterile (so it does not require refrigeration), and is heated to 138 C (280 F) for 2 sec

These are the minimum times required by law, and are generally slightly exceeded (for example, 167F for 18 seconds).

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