The main difference between pasteurized and ultra pasteurized milk is that the pasteurized milk is treated at 161 °F (72 °C) for 15 seconds whereas the ultra–pasteurized milk is treated at 280 °F (138 °C) for 2 seconds. Furthermore, pasteurized milk is packed untreated with H2O2 while ultra-pasteurized milk is treated with H2O2 during packaging.
Pasteurized and ultra-pasteurized milk are two types of processed milk with a longer shelf life. The main purpose of pasteurization is to kill the bacteria that spoil the milk. Both pasteurized and ultra-pasteurized milk have to be refrigerated to avoid spoilage.
Key Areas Covered
1. What is Pasteurized Milk
– Definition, Process, Storage
2. What is Ultra Pasteurized Milk
– Definition, Process, Storage
3. What are the Similarities Between Pasteurized and Ultra Pasteurized Milk
– Outline of Common Features
4. What is the Difference Between Pasteurized and Ultra Pasteurized Milk
– Comparison of Key Differences
Key Terms
HTST, Pasteurization, Pasteurized Milk, Ultra Pasteurized Milk, UHT
What is Pasteurized Milk
Pasteurized milk is the milk that has been heated at 161 °F for 15 seconds or 145° F for 30 minutes. The method is called high-temperature short time (HTST) treatment. The main purpose of pasteurization is to kill bacteria. After pasteurization, the milk is packed under clean and sterilized conditions. Pasteurized milk has to be refrigerated at temperatures less than 45°F. Pasteurized milk has to be used as soon as possible for the best quality and taste after opening the package.
Figure 1: Pasteurization Process
However, some bacteria may still live after the heat treatment. But, they are very in low numbers. These bacteria are considered not harmful, and they do not spoil milk under refrigerated conditions. The growth of these bacteria occurs later in the shelf life called the past code. Contamination and improper refrigeration result in the spoilage of milk before its time.
What is Ultra Pasteurized Milk
Ultra-Pasteurized milk is the milk heated to 280 °F for 2 seconds. The method is called the ultra-high temperature (UHT) treatment. The high temperature used here is higher than the temperature used for regular pasteurization. Hence, ultra-pasteurization virtually kills all the bacteria in milk. Also, this milk is packed under near sterilized conditions to prevent contamination. However, this milk has to be refrigerated as it is not canned. Due to the high heat used, ultra-pasteurized milk has a ‘cooked’ flavor. The shelf life of the ultra-pasteurized milk is 30-90 days under refrigerated conditions. After opening, it has to be used within 7-10 days and have to be kept in the refrigerator at 34-38 °F.
Figure 2: Ultra Pasteurization Line
Ultra-Pasteurization is most often used for speciality dairy products and creams. However, the technique is becoming popular for regular milk as well.
Similarities Between Pasteurized and Ultra Pasteurized Milk
- Pasteurized and ultra-pasteurized milk are two types of processed milk.
- Both are subjected to a particular heat for a particular time.
- They have to be packed under sterilized conditions in order to prevent further contamination.
- They are packed in paper or plastic.
- Both have to be kept in the refrigerator to prevent spoilage.
- Pasteurization may reduce the nutritional value of milk briefly. Some vitamin C can be destroyed.
Difference Between Pasteurized and Ultra Pasteurized Milk
Definition
The pasteurized milk refers to the milk that has been exposed briefly to high temperatures to destroy microorganisms and prevent fermentation whereas the ultra-pasteurized milk refers to the processed milk has been sterilized by heating it above 135 °C (275 °F).
Heat Treatment
Pasteurized milk is treated at 161 °F for 15 seconds whereas the ultra-pasteurized milk is treated at 280 °F for 2 seconds.
Method
The method that produces pasteurized milk is called the high temperature short time (HTST) treatment while the method that produces ultra-pasteurized milk is called the ultra-high temperature (UHT) treatment.
Killing of Bacteria
Some bacteria can survive in pasteurized milk while ultra-pasteurized milk is nearly sterile.
Nutrition Loss
Pasteurized milk may lose 3-4% of thiamine, >5% of vitamin E, and >10% of biotin during the heating process while whey protein in the ultra-pasteurized milk denatures.
Recontamination
Recontamination is possible in pasteurized milk while recontamination is minimized or prevented in ultra-pasteurized milk.
Equipment
Equipment used to produce pasteurized milk is sanitized and can be exposed to the external environment while the equipment used to produce ultra-pasteurized milk is sterilized and is not exposed to the external environment.
Package Treatment
The pasteurized milk is not treated with H2O2 during packing while the ultra-pasteurized milk is treated with H2O2 during packing.
Shelf Life
Pasteurized milk is best before 10-21 days while ultra-pasteurized milk is best before 30-90 days.
After Opening
Pasteurized milk should be used as soon as possible after opening while ultra-pasteurized milk can be kept in the refrigerator at 34-38 °F for 7-10 days after opening.
Conclusion
The pasteurized milk is heated to 161°F for 15 seconds while ultra-pasteurized milk is heated to 280°F for 2 seconds. Therefore, virtually all bacteria are killed in the ultra-pasteurized milk while some may remain in pasteurized milk. On that account, ultra-pasteurized milk has a longer shelf life than pasteurized milk. The main difference between pasteurized milk and ultra pasteurized milk is the heat treatment and shelf life.
Reference:
1. “What Is Pasteurized Milk?” Mercola.com, Dr. Mercola’s Natural Health Newsletter, Available Here
2. Forristal, Linda Joyce. “Ultra-Pasteurized Milk.” The Weston A. Price Foundation, 23 May 2004, Available Here
Image Courtesy:
1. “Simple Pasteurization” By Emma – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Tetra Pak processing equipment Tetra Lactenso Aseptic” By tetrapak – (CC BY-SA 2.0) via Commons Wikimedia
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