Why Does Swiss Cheese Have Holes?

Emmentaler cheese, referred to as Swiss cheese in the United States, is best known for its holey appearance. But, why are there holes in Swiss cheese? Wouldn’t it be better (and tastier) to just have a full slice?

The holes — called “eyes” in the cheese-biz — are part of the Emmentaler-making process, which originated in the Emme River valley in Switzerland. Cheesemakers in other regions follow a similar process, including Norway, where the product is called Jarlsberg.

Here’s how the holey cheese is made:

Cultures of the bacteria S. thermophilus, Lactobacillus and P. shermani are mixed with cow’s milk. The resulting curds are pressed in large molds around three feet in diameter and six inches thick. Then, the pressed curds are soaked in brine, which ultimately forms the cheese’s rind, wrapped in a film, and stored in a cave at between 72 and 80 degrees Fahrenheit where they will age, or ripen. 

And here is where the holes come in. As the cheese ripens, the bacteria are still munching away. One strain — P. shermani — produces carbon dioxide in the process, which forms small bubbles in the cheese. Later, when the cheese is sliced, the bubbles burst, leaving behind empty holes.

If you live in the United States, you might have noticed that the sizes of the holes in Emmentaler have shrunk over the past decade. In 2001, The U.S. Department of Agriculture revised its rules on the cheese, which included minimizing the allowable size of holes in all Grade-A Swiss so that it doesn’t clog up modern deli slicers. In order to receive the rating, the holes have to be between 3/16 and 13/8 of an inch in diameter.

Want to see if your Emmentaler’s up to par? Check out the USDA’s 14-page list of the cheese’s standards.