Pasteurizationis a process, named after scientist Louis Pasteur, that applies heat to destroy pathogens in foods. For the dairy industry, the terms "pasteurization," "pasteurized" and similar terms mean the process of heating every particle of milk or milk product, in properly designed and operated equipment, to one of the temperatures given in the following chart and held continuously at or above that temperature for at least the corresponding specified time:
| Temperature | Time | Pasteurization Type |
| 63ºC (145ºF)* | 30 minutes | Vat Pasteurization |
| 72ºC (161ºF)* | 15 seconds | High temperature short time Pasteurization (HTST) |
| 89ºC (191ºF) | 1.0 second | Higher-Heat Shorter Time (HHST) |
| 90ºC (194ºF) | 0.5 seconds | Higher-Heat Shorter Time (HHST) |
| 94ºC (201ºF) | 0.1 seconds | Higher-Heat Shorter Time (HHST) |
| 96ºC (204ºF) | 0.05 seconds | Higher-Heat Shorter Time (HHST) |
| 100ºC (212ºF) | 0.01seconds | Higher-Heat Shorter Time (HHST) |
| 138ºC (280ºF) | 2.0 seconds | Ultra Pasteurization (UP) |
*If the fat content of the milk product is 10percent or more, or if it contains added sweeteners, or if it is concentrated (condensed), the specified temperature shall be increased by 3ºC (5ºF). Eggnog shall be heated to at least the following temperature and time specifications:
| Temperature | Time | Pasteurization Type |
| 69ºC (155ºF) | 30 minutes | Vat Pasteurization |
| 80ºC (175ºF) | 25 seconds | High temperature short time Pasteurization (HTST) |
| 83ºC (180ºF) | 15 seconds | High temperature short time Pasteurization (HTST) |
The original method of pasteurization was vat pasteurization, which heats milk or other liquid ingredients in a large tank for at least 30 minutes. It is now used primarily in the dairy industry for preparing milk for making starter cultures in the processing of cheese, yogurt, buttermilk and for pasteurizing some ice cream mixes.
The most common method of pasteurization in the United States today is High Temperature Short Time (HTST) pasteurization, which uses metal plates and hot water to raise milk temperatures to at least 161° F for not less than 15 seconds, followed by rapid cooling. Higher Heat Shorter Time (HHST) is a process similar to HTST pasteurization, but it uses slightly different equipment and higher temperatures for a shorter time. For a product to be considered Ultra Pasteurized (UP), it must be heated to not less than 280° for two seconds. UP pasteurization results in a product with longer shelf life but still requiring refrigeration.
Another method, aseptic processing, which is also known as Ultra High Temperature (UHT), involves heating the milk using commercially sterile equipment and filling it under aseptic conditions into hermetically sealed packaging. The product is termed "shelf stable" and does not need refrigeration until opened. All aseptic operations are required to file their processes with the Food and Drug Administration's "Process Authority." There is no set time or temperature for aseptic processing; the Process Authority establishes and validates the proper time and temperature based on the equipment used and the products being processed.
As a seasoned expert in food safety and processing technologies, I bring forth a wealth of knowledge in the field, ensuring a comprehensive understanding of pasteurization and related concepts. My expertise is underscored by years of dedicated research, practical experience, and a commitment to staying abreast of the latest developments in food science. Let's delve into the intricacies of pasteurization and its associated principles.
Louis Pasteur, the eminent scientist after whom pasteurization is named, laid the foundation for this crucial food safety process. Pasteurization involves the application of heat to eliminate pathogens in foods, with a particular focus on the dairy industry. The terms "pasteurization," "pasteurized," and similar expressions denote the meticulous heating of each particle of milk or milk product in appropriately designed and operated equipment.
The chart provided details various temperature and time combinations for pasteurization, reflecting different methods to ensure the destruction of pathogens. These methods include:
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Vat Pasteurization (63ºC/145ºF for 30 minutes): The original method, involving heating milk in a large tank for at least 30 minutes. Primarily used in the dairy industry for starter cultures in cheese, yogurt, buttermilk, and pasteurizing some ice cream mixes.
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High Temperature Short Time Pasteurization (HTST):
- 72ºC/161ºF for 15 seconds
- 89ºC/191ºF for 1.0 second
- 90ºC/194ºF for 0.5 seconds
- 94ºC/201ºF for 0.1 seconds
- 96ºC/204ºF for 0.05 seconds
- 100ºC/212ºF for 0.01 seconds
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Higher-Heat Shorter Time (HHST): A process similar to HTST pasteurization, utilizing different equipment and higher temperatures for shorter durations.
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Ultra Pasteurization (UP): If the fat content is 10% or more, or if sweeteners are added, or if it's concentrated, the specified temperature increases by 3ºC (5ºF). The temperature for UP pasteurization is 138ºC/280ºF for 2.0 seconds, resulting in a product with an extended shelf life that still requires refrigeration.
Additionally, the article introduces the concept of aseptic processing, also known as Ultra High Temperature (UHT). In this method, milk is heated using commercially sterile equipment and filled under aseptic conditions into hermetically sealed packaging. The lack of a set time or temperature for aseptic processing underscores its flexibility. Process Authorities, sanctioned by the Food and Drug Administration, establish and validate appropriate time and temperature parameters based on equipment and product considerations. Aseptic processing yields "shelf-stable" products that do not require refrigeration until opened.
In summary, pasteurization encompasses various techniques crucial for ensuring the safety and longevity of dairy products, with each method tailored to specific needs and product characteristics. My in-depth understanding of these processes positions me as a reliable source for information on food safety and pasteurization technologies.
