Pasteurization is a pretty big deal—and one that we may take for granted. I, for one, appreciate this process as well as its discoverer, Louis Pasteur, as it allows us to enjoy our milk safely.
Pasteurization was first used in wines in France in 1862. The souring of beers and wines was a problem causing lots of spoilage – and costing wine producers money. After pasteurization, a process that only involves heat, was found to be successful in wines, they started using the process for milk.
Today, thanks to our friend Louis, we can go to the fridge and grab a gallon of pasteurized milk and feel certain we are not only getting important nutrients, but we are also drinking one of the safest foods in the world.
Why Do We Pasteurize Milk?
Pasteurization improves the safety of milk and other dairy foods by killing harmful bacteria, viruses and other pathogens that are known to cause foodborne illnesses.
Safety of Pasteurized Milk
Pasteurization is highly effective at ensuring the safety of milk by eliminating harmful microorganisms that can cause illness, including:
- Salmonella
- E. coli
- Listeria monocytogenes
- Campylobacter
- Mycobacterium tuberculosis (which causes tuberculosis)
By heating the milk to a specific temperature for a designated amount of time (depending on the pasteurization method), the process kills or deactivates these microorganisms without compromising the milk's quality.
Key Safety Aspects of Pasteurized Milk:
- Reduced Risk of Disease: Pasteurization significantly reduces the risk of foodborne diseases in milk, such as tuberculosis, brucellosis and Q fever, which can be transmitted from animals to humans through raw milk.
- Shelf-Life Extension: Pasteurized milk lasts longer than raw milk due to the reduction in harmful bacteria, which helps slow down spoilage. Milk should be kept at 38-40°F at all times to ensure it remains safe.
- Consistency: Pasteurization provides a standardized level of microbial safety, ensuring that you and your family have food-safe milk in your fridge.
How Does Pasteurization Impact Milk’s Nutrition?
Pasteurization has minor, insignificant impacts on milk’s nutrient profile, and pasteurized milk is not only safe, but also has 13 essential nutrients to contribute to you family’s health and wellness.
Proteins:
The heat from pasteurization can slightly alter the structure of proteins like casein and whey in milk, but it does not destroy them. Pasteurized milk is a good source of high-quality protein, which is important for muscle growth, repair and maintenance at all life stages.
Vitamins:
- Vitamin A: Pasteurization does not have a significant impact on vitamin A levels in milk, so it remains a good source of this essential nutrient, which supports vision, immune function and skin health.
- Vitamin B12: There is minimal loss of vitamin B12 during pasteurization, so milk continues to be an excellent source of this vitamin, which is crucial for nerve function and the production of red blood cells.
- Vitamin D: Vitamin D can be slightly reduced during pasteurization, but most milk sold commercially is fortified with additional vitamin D, ensuring that it remains a strong source of this nutrient. Vitamin D is important for bone health and immune function.
- B Vitamins (B1, B2, B3, B6, and Folate): Some B vitamins may be reduced by pasteurization, especially in high-temperature treatments, but the reduction is minimal, and milk remains a good source of these vitamins.
Minerals:
Pasteurization does not significantly affect the mineral content of milk, like calcium, phosphorus or magnesium. Milk remains a good source of calcium, which is essential for strong bones and teeth, and phosphorus, which supports cellular function.
Fat & Carbohydrates:
The fat content in milk remains largely unaffected by pasteurization, and lactose (the primary carbohydrate in milk) also remains stable. Some specialized processes like homogenization (which often accompanies pasteurization) can change the structure of milk fat, but it doesn't affect its nutritional value.
Other Health Considerations:
- Enzyme Activity: Pasteurization does inactivate some enzymes in milk (such as lipase), which may impact the flavor and spoilage rates of raw milk. These enzymes are not essential for human nutrition, so their inactivation is not a concern for your health.
- Digestibility: Pasteurization does not significantly affect the digestibility of milk for most people, including those with lactose intolerance. While lactose intolerance can cause digestive discomfort, pasteurized milk still contains lactose, which can be broken down by lactase enzymes in the digestive system.
So How Does the Pasteurization Process Work?
Preparing the Milk:
Before pasteurization, milk is prepared by filtering out any impurities and homogenizing the product to ensure uniformity. Sometimes, milk is preheated to a lower temperature before the pasteurization process begins to help reduce the energy needed during the actual pasteurization phase.
Heating the Milk:
The milk is rapidly heated to a specific temperature. The exact temperature and time depend on the type of milk and the target microorganisms.
- Low-Temperature, Long Time (LTLT): Also known as batch pasteurization, this method involves heating the milk to 145°F for about 30 minutes.
- High-Temperature, Short Time (HTST): This method heats the milk to 161°F for 15-20 seconds. HTST ensures a higher throughput while still killing harmful microorganisms.
- Ultra-Pasteurization (UP): For dairy foods like cream, the pasteurization temperature can be as high as 280°F for two seconds to achieve longer shelf life.
- Ultra-High Temperature (UHT): Also known as Ultra-Heat Treatment, this involves heating milk to 275–302°F for 2–5 seconds. UHT is used in milk that is intended to have a long shelf life without refrigeration.
Holding the Milk’s Temperature:
After milk reaches the target pasteurization temperature, it is held at that temperature for the above specified amount of time. The holding period is crucial for ensuring that the heat has sufficiently killed harmful pathogens. The time is carefully controlled to balance safety and the preservation of the milk’s taste, texture and nutritional content.
Cooling the Milk:
Once the required pasteurization time has been completed, the milk is rapidly cooled to a temperature that inhibits further microbial growth. This cooling step is important to preserve the quality of the product. The cooling process may occur in a heat exchanger, which can also help recover energy by preheating incoming products with the outgoing hot liquid.
Packaging the Milk:
After cooling, the pasteurized milk is typically packaged in sterilized containers to prevent contamination. For some milk, like shelf stable milk, this step is done under sterile conditions, using vacuum-sealed or air-tight packaging to extend shelf life.
Storing the Milk:
The final product is stored under controlled conditions to maintain its safety and quality. Proper storage ensures that the milk remains free of microbial contamination during its shelf life.
What About Raw Milk? Is it Safe?
Raw milk poses significant health risks due to the potential presence of harmful pathogens. These risks are especially dangerous for vulnerable populations, such as children, the elderly, pregnant women and individuals with weakened immune systems.
Raise Your Glass to Safe Milk!
From farm to fridge, lots of practices have been put into place to keep our food safe, and since we don’t see widespread foodborne illness in America, we often take those practices for granted. Additional safeguards like pasteurization complete the picture.
So, the next time you grab a glass of ice-cold pasteurized milk, give a toast to good ol’ Louis Pasteur for keeping us safe and satisfied. Thanks, Louis!
