Did you know that the expiration date on the jug of milk inside your fridge is somewhat amazing? Considering all of the factors that go into preserving a jug of milk, it’s almost a miracle that American milk can be kept for so long.
A typical gallon of milk in the United States can last in the back of your fridge for about three weeks. But Brazilian milk only lasts three to eight days on average. And Ugandan milk starts turning almost as soon as it leaves the cow, lasting only a day or so, Nadia Whitehead writes for NPR.
To get milk to the customer with as long a shelf life as possible, American dairies rely on “the cold chain” – a complex system designed to keep milk as cold as possible for as long as possible. As soon as the milk is pumped and pasteurized, it moves from fridge to truck to fridge as the milk moves around the country. But for many countries around the world, limited resources make the cold chain impossible to manage, Whitehead writes.
"Many people [in Uganda] don't have the means to cool milk," William Kisaalita, an engineer at the University of Georgia, tells Whitehead. Kisaalita was born in Uganda. He notes that not only are wages low, but refrigerators and electricity are prohibitively expensive.
This doesn’t just pose a problem for consumers looking for an ice-cold glass of milk: it also means that Ugandan farmers can lose up to half of their product due to spoilage during the rainy season when cows produce the most, Kisaalita says. However, engineers around the world are trying to tackle the problem of bringing the cold chain to countries without the resources to power a fleet of refrigerated trucks. Kisaalita, for one, is working on a design for a cooling system powered by biogas from cow dung so Ugandan farmers might get at least one more day out of their milk. And one milk company in Brazil has doubled the shelf life of its product by using nanotechnology to build antimicrobial and antibacterial materials into the plastic it uses in its bottles.
Meanwhile, about 32 percent of milk in the United States goes to waste every year — it's one of the top three foods wasted in the country according to U.S. Department of Agriculture data from 2010. That’s partly because of how confusing it is to understand expiration dates, Roger Cormier writes for Mental Floss. The federal government doesn’t actually regulate how companies print expiration dates on any food or drink aside from baby formula and only 20 states have laws regulating food expiration. In some states, the date marks when stores need to sell the milk by to give customers enough time to enjoy it at home; in others, it shows when the milk will taste its best.
The next time you go to throw out that carton of milk, take a moment to appreciate its miraculously long tenure in your fridge. After all, the fact that it was good for so long is something rare indeed.