The average American drinks 25 gallons of milk each year, which is why it’s important to know some facts about milk.
Milk that comes from a cow typically has some bacteria. Most bacteria are generally harmless, although some types have the potential to cause serious illness or death.
To kill harmful bacteria, milk is heated through a process called pasteurization. Pasteurization uses a combination of time and temperature to make milk safer. The higher the temperature, the shorter the amount of time the milk needs to be at that temperature. The milk we drink is generally heated to 161 degrees Fahrenheit for at least 15 seconds, and is then quickly cooled.
Some milk products are “ultra pasteurized,” which means the milk has been heated under pressure, for a shorter amount of time (2 seconds), at a higher temperature (280 degrees Fahrenheit). Ultra pasteurized milk has a longer shelf life – up to 30 days before it is opened. Because ultra pasteurized milk is heated at a higher temperature, it can have a cooked milk taste.
Commercially sterilized milk (called “aseptic”) is cooked to an even higher temperature for a shorter amount of time. Commercially sterile milk can safely remain on the shelf for months, and does not need to be refrigerated until opened. Like ultra pasteurized milk, the higher temperature sterilization process may alter the taste of the milk.
Milk that comes directly from the cow separates into fat (cream) and liquid. To create a smooth, even consistency, milk is homogenized which is the process of removing some of the fat, and breaking down the remaining fat into smaller molecules that remain dispersed in the milk. Homogenization does not alter the nutritional value of milk.
Expiration Dates and Refrigeration
Consumers should adhere to the expiration date on milk packaging. And once the container is opened – whether it is pasteurized, ultra pasteurized or commercially sterile– milk should be refrigerated and used within seven days. Milk that is exposed to air and fluctuating temperatures exposes the milk to bacteria, which can grow. Refrigeration at or below 40 degrees Fahrenheit and use within one week prevents bacteria exposure and milk spoilage.
Some milk products have labels that state: “We pledge not to treat our cows with the hormone rBGH,” or “Hormone free.” While hormones are neither added to nor present in milk, some farmers treat their cows with growth hormone to stimulate milk production. And while administering cows with growth hormone has nothing to do with milk safety, some consumers are uncomfortable with the practice and would prefer to purchase milk from cows that have not been treated with rBGH.
More recently, some consumers have taken an interest in unpasteurized or “raw” milk. Raw milk can come from cows, goats or sheep. According to the U.S. Centers for Disease Control and Prevention (CDC), unpasteurized milk is 150 times more likely to cause food borne illness than pasteurized milk. In 2012, there were six pathogenic E. coli outbreaks related to raw milk. Young children, pregnant women, and anyone with a compromised immune system should not drink unpasteurized milk, or eat cheese or other food products made from unpasteurized milk because they are more likely to become ill, and are more likely to suffer dire consequences including death.
When in Doubt, Throw it Out
If your milk ever doesn’t look, smell or taste right, or if you have any question about the safety of your milk or any food product, it’s best to get rid of it. As always, when in doubt, throw it out.
Source: Jennifer McEntire, PhD, IFT Member
For More Information:
United States Food and Drug Administration
U.S. Centers for Disease Control and Prevention
The National Dairy Council
Categorized under: Nutrition