What Is Ultra Pasteurized Milk?

Milk's Ultra-Pasteurization Process:

While most milk goes through a standard pasteurization process, UHT milk goes through ultra-pasteurization, which safely heats the milk to a higher-than-usual temperature. This, like regular pasteurization, kills bacteria in the milk that may be harmful or cause the milk to spoil, producing milk with a longer life. 

UHT milk can sit out unrefrigerated for about three months, and this can vary by brand. Once the container is opened, the milk should be refrigerated and has the same shelf life as other milk (seven to ten days).

Choosing Between Pasteurized vs Ultra-Pasteurized vs UHT Milk

Here’s a look at the key differences between pasteurized, ultra-pasteurized, and UHT milk. Each method uses different heat treatments to kill bacteria and extend shelf life, giving you options depending on how long you need to store your milk and how fresh you want it. 

Whether you prefer the shorter shelf life of pasteurized milk or the longer convenience of UHT, this will help you make the right choice.

Pasteurized Milk
Pasteurized milk is heated to 72°C (161°F) for 15 seconds. This method of heat treatment is designed to preserve the milk’s natural nutrients while ensuring safety. Pasteurized milk must be refrigerated and has a shelf life of 10–21 days. Packaging typically involves paper or plastic, and the package remains untreated.

• Heat Treatment: 72°C (161°F) for 15 seconds

• Shelf Life: 10–21 days

• Storage: Requires refrigeration
   

Ultra-Pasteurized Milk
Ultra-pasteurized milk undergoes a more intense heat treatment, where it is heated to 138°C (280°F) for 2 seconds. This process extends the milk’s shelf life to 30–90 days under refrigeration. Ultra-pasteurized milk is packaged in paper or plastic, with the package being treated with hydrogen peroxide (H₂O₂) to ensure sterility and preserve freshness.

• Heat Treatment: 138°C (280°F) for 2 seconds

• Shelf Life: 30–90 days

• Storage: Requires refrigeration
   

UHT Milk
UHT milk is heated to 138°C (280°F) or higher for at least 2 seconds, making it nearly sterile. This high heat treatment not only kills bacteria but also allows the milk to remain shelf-stable for up to 6+ months without refrigeration, until it is opened. UHT milk is packaged in a hermetically sealed container that is sterilized, ensuring the milk remains fresh and safe to consume.

• Heat Treatment: 138°C (280°F) or higher for 2+ seconds

• Shelf Life: 6+ months (unopened, no refrigeration needed)

• Storage: Shelf-stable, no refrigeration required