From The Reader’s Digest

Ask for a glass of milk in an American home, and your host will likely pull an ice-cold gallon out of the fridge. But if you do the same in a European country, you’ll probably receive a room-temperature glass. What gives?

 Believe it or not, most of the world doesn’t refrigerate milk. But before you go nuts with worry about food poisoning, you should know that it’s completely safe to drink.

Turns out, the major difference lies in the method by which milk is processed. Almost all milk is pasteurized, meaning it undergoes extreme heat in order to kill illness-causing bacteria. The U.S. and Canada use a pasteurizing technique called high-temperature short-time pasteurization, or HTST. 

 HTST is cheaper and more efficient because it processes milk in larger batches, but as a result, milk has a shorter shelf life—around seven to 10 days—and must be refrigerated.

 Meanwhile, the rest of the world uses ultra-high-temperature or ultra-heat-treated pasteurization (UHT), which heats the milk to an even higher temperature than HTST. The result: Milk that stays fresh outside of the fridge for about three months.

In the early 1990s, one company attempted to sell UHT milk on American shelves, but it never caught on. Why? For starters, the high temperatures make UHT milk taste a bit more “cooked” than HTST milk. But most likely, Americans’ obsession with refrigeration is to blame.

 So forget about whether you take your glass half full or half empty. The real debate lies in whether you like it warm or cold.