Pasteurization and milk preservation

Pasteurization refers to the process of heating every particle of milk or milk of the different classes to atleast 63°C (145°F) for 30 minute or 72°C (161°F) for 15 seconds or an approved temperature and time combination that will serve to negative phosphatase test, the milk is immediately cooled to 5°C (41°F) or below.

• Pasteurization process was invented by Louise Pasteur during 1860-1864.
• The temperature-time requirement for pasteurization was fixed as 61.7°C for 30 minute on the basis of destruction of Mycobacterium tuberculosis, which was considered as the most heat resistant organism.
• Later, it was changed to 62.8°C for 30 minute based on the time-temperature required for destruction of Coxiella burnetii, which is more heat tolerate than Mycobacterium tuberculosis.
• Objective of pasteurization:
  • Public health aspect: Safe for human consumption by destroying all bacteria that may be harmful to health.
  • Keeping quality aspect: Improve the keeping quality – destroyed some undesirable enzymes and many spoilage bacteria.
• Various methods of pasteurization:
  1. Batch pasteurization / low temperature long time pasteurization (LTLT)
     • Water jacketed type
     • Water spray type
     • Coil vat type
  2. High temperature short time pasteurization (HTST)
     • Tubular heat exchanger
     • Plate heat exchanger
  3. Vacuum pasteurization
  4. Flash pasteurization
  5. Ultra high temperature treatment (UHT)
     • Direct
     • Indirect
  6. Ultra pasteurization (Uperisation)
  7. Stassanization

For more in detail please download the attachment- PPT.