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Ever Wondered Why Swiss Cheese Has Holes?

“Swiss cheese is always described as the cheese with holes,” says Mark Johnson, PhD, a scientist at the Center for Dairy Research at the University of Wisconsin.

Platter of Swiss cheese

Also known as Emmenthal cheese, it’s thought to have been made for the first time in Swiss Alps in the 14th century. “It was a hard cheese that had a long shelf life and that could easily be transported down the mountains where it was made,” adds Johnson. “It has a firm body and has a nutty but sweet flavor. It is also very low in salt compared to other cheeses.”

Today, however, the term Swiss cheese refers not to where the cheese comes from but to the type of cheese. In other words, it all comes down to how the cheese is made. So, why does Swiss cheese have holes?

It's all about the bacteria that's used in its production. “Cheesemakers add a special bacteria called Propionibacterium shermanii. This bacteria ferments lactic acid and produces carbon dioxide,” explains Johnson. “Carbon dioxide collects in certain spots in the cheese and produces a large bubble, or eye. No other cheese uses this culture.”

All Swiss cheese share this characteristic. “There are other versions of Swiss, such as baby Swiss, Maasdam, Jarlsberg and Emmentaler, that are made with Propionibacterium, so they also have eyes,” he adds.

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