In this video, we're going to continue to talk about moist heat as we talk more about pasteurization. Pasteurization is a process that was first discovered by Louis Pasteur and was also named after him. Pasteurization refers to the brief boiling of a specific product, such as milk or wine, to disinfect it and make it safe for consumption without significantly changing its properties, such as its taste or flavor.
Most pasteurization is completed by the method known as high temperature short time method, or HTST method for short, which exposes the product to temperatures of about 165 degrees Celsius for only about 15 seconds. The temperature used in the HTST method is typically not high enough to sterilize the product, and some microbes are likely to remain even after HTST pasteurization. However, another method implements even higher temperatures and shorter times than the HTST method, and this is the ultra high temperature, or UHT pasteurization method, which uses such high temperatures that it's capable of actually sterilizing the product and killing all of the microbes. For example, the UHT method would use temperatures up to 280 degrees Celsius for just 3 seconds.
We can also visualize the HTST and the UHT pasteurization methods, which were discovered by Louis Pasteur. Notably, milk extracted from cows contains many different types of microorganisms, and may be unsafe to drink directly. Pasteurization is a process that helps control the microbial growth in the milk.
There are two methods of pasteurization: the high temperature short time method, or HTST method, is implemented with temperatures around 165 degrees Celsius for approximately 10 to 20 seconds. This process yields milk safe to consume without significantly changing the flavor and taste. However, as the HTST method does not use temperatures high enough for sterilization, it is important to implement preservation techniques such as refrigeration to help delay the growth of the microbes. Milk that is refrigerated typically has gone through the HTST pasteurization process.
On the other hand, the ultra high temperature pasteurization method, or UHT method, uses much higher temperatures, around 280 degrees Celsius, for only 3 seconds. The high temperatures are enough to sterilize and kill all of the microbes, making the milk shelf-safe. Therefore, this milk can be stored at room temperature and sometimes is found on grocery store shelves not requiring refrigeration.
This concludes our brief lesson on pasteurization, and we will get some practice applying these concepts and learn more about other physical methods of controlling microbial growth as we move forward in our course. See you all in our next video.
