By Mike Pomranz
Updated May 29, 2015
Credit: © RubberBall / Alamy

It took nearly a century, but scientists in Switzerland believe they’ve finally figured out why their country’s eponymous cheese has holes.

According to, the study of Swiss cheese dates back to at least 1917, when American scientist William Clark concluded that the holes were made by carbon dioxide released from bacteria in the milk. But what the hell do Americans know about Swiss cheese? Apparently, not as much as the Swiss.

Researchers at Switzerland’s Agroscope research center concluded that the culprit is tiny hay particles present in traditional milking buckets. Part of what tipped the scientists off to the cause was that modern Swiss cheese has fewer holes than it used to. “It's the disappearance of the traditional bucket,” Agroscope spokesman Regis Nyffeler said. Now that the old buckets have been replaced by sealed milking machines, it “completely did away with the presence of tiny hay particles in the milk.”

The researchers confirmed their findings by adding different amounts of hay dust to milk during the cheese-making process. They found they were able to regulate the number of holes.

With that mystery solved, Swiss scientists will have to find some other major question to ponder—like “What’s up with hot cocoa?”