Spoiled milk can do a disgusting number on a cup of coffee, bowl of cereal, or strawberry smoothie, and an unexpected gulp of it is a definitely off-putting way to start the day. To date, the best bet for steering clear of bad milk is the whiff test—that is, take a sniff and if the milk in your carton smells funky, don’t drink it. The problem is that sense of smell isn’t always a reliable guide, and bad milk periodically outwits the human nose.

Spoiled-milk surprises, however, may soon be a thing of the past, thanks to a technological innovation developed at the University of California, Berkeley, and the National Chiao Tung University in Taiwan. Teams from these institutions have developed