Pasteurization, UHT, and Homogenization – What’s the Difference?
Animal milk has to be processed before it is fit for human consumption. For the most part, milk products sold at the grocery store are pasteurized and homogenized. Some have undergone ultra-high-temperature (UHT) processing. If all of these terms confuse you, take comfort in knowing you are not alone. You wouldn’t be expected to understand them unless you were in the food processing business.
Cedarstone industry is a Houston company that manufactures pasteurization and UHT equipment, in addition to other industrial machinery. They say that pasteurization, UHT processing, and homogenization are three separate processes designed to achieve different things.
If you are familiar with any of the three terms, it is probably pasteurization. Milk is pasteurized in order to remove harmful bacteria. The process involves heating milk and then quickly cooling it. In the early days, pasteurization occurred at about 145°F for 30 minutes. These days, processors prefer raising the temperature to just over 161° for 15 seconds. This type of pasteurization is known as high-temperature short-time (HTST) pasteurization.
It should be noted that pasteurization is not limited just to milk. Other types of food products are pasteurized as well. The key difference between pasteurization and UHT processing is temperature. Pasteurization always occurs at temperatures of 212°F or lower.
As its name suggests, UHT processing involves higher temperatures — usually between 250°F and 284°F. Depending on the process utilized, food doesn’t have to be exposed to high temperatures for very long. But just as with pasteurization, the key to ending up with a desirable product is cooling it as quickly as possible.
Milk subjected to UHT processing is labeled as ultra-pasteurized. It offers one big advantage over traditional pasteurized and HTST products: longer shelf life. Ultra-pasteurized milk can be safely stored for up to nine months.
Where pasteurization and UHT processing are designed to kill bacteria and deactivate certain enzymes, homogenization is all about preparing a milk product for retail sale. As such, homogenization always occurs after pasteurization. Its purpose is to break down milk’s fat molecules.
Why is homogenization necessary? As you know, molecules of different weights do not always blend well together. Because fat molecules are the lightest constituents in pasteurized milk, they naturally float to the surface where they appear as cream. Consumers do not want a creamy ‘head.’ They want their milk fully and completely blended. That is what homogenization does.
Homogenization breaks down fat molecules so that they are small enough to be suspended in the milk, rather than floating to the surface. It is a completely mechanical process that doesn’t require the introduction of any other components. In simple terms, homogenization doesn’t require additives.
In closing, there are consumers who insist on using only raw milk. Their milk comes directly from cows, goats, or other animals. It is neither pasteurized nor homogenized. As you might imagine, the FDA isn’t all that enthusiastic about raw milk. They insist that pasteurization does not reduce milk’s nutritional value, an assertion fans of raw milk dispute.
Raw milk producers are free to consume their products as they see fit. However, they must be licensed by their respective states to sell raw milk at retail. Some states take a hardline stance toward raw milk while others openly embrace it.
Now you know the differences between pasteurization, ultra-pasteurization, and homogenization. You are better equipped to understand milk labels at the grocery store. And if you want to impress your friends and family members with your newfound knowledge, go ahead and explain it to them. You will probably be the smartest one in the room — at least temporarily.