The milk you drink in the good ol’ United States of America has most likely been heated for about 15 seconds at 161°F before it reaches your mouth. That process—the most common form of pasteurization—kills off harmful bacteria and helps ensure that you don’t get diseases like tuberculosis, listeriosis and typhoid fever—thanks, Louis Pasteur—just from, say, enjoying a bowl of cereal in the morning. But this type of pasteurization doesn’t kill off all bacteria, which explains why most milk spoils relatively quickly—only about one week, on average, past the sell-by date.
As it turns out, though, there is another method by which milk is pasteurized, allowing it to last for months. When milk is ultra-heat-treated—which is to say, heated to 284°F for just three seconds—it is rendered virtually bacteria-free, which means it can last much longer than regular pasteurized milk. The process has gained traction in the past half-century or so. Although ultra-heat-treated milk hasn’t really caught on in North America, it is popular in China, where milk consumption has recently taken off, according to an intriguing BBC report by the science writer Veronique Greenwood.
The torching milk undergoes as part of the ultra-heating process changes its chemical composition in a couple of interesting ways that set it apart from the milk we’re used to, Greenwood writes. For one, the taste is different. Ultra-heat-treated milk is generally sweeter, a bit more gelatinous and sometimes more sulfurous than regular milk. (This is due primarily to the Maillard reaction—or browning, in lay speak.) The other difference is that heating milk at such a high temperature throws its proteins into disarray, which makes it difficult to produce cheese.
Since we’re so used to regular pasteurized milk in the United States, it seems safe to say that ultra-heat-treated milk won’t overshadow it any time soon. But ultra-heat-treated milk does have clear advantages if you need to stock up or don’t like to go shopping that often. (And if you prefer the distinct taste, even better.) If you can’t get your hands on it, though, there is always condensed milk, which, left unopened, lasts for about a year past its expiration date—and tastes divine.