Why Does Swiss Cheese Have Holes? The Answer Is Surprisingly Simple!

Swiss cheese has holes due to carbon dioxide bubbles that develop during its production. That's the straightforward explanation.

For those keen on delving deeper into the science behind Swiss cheese , here's a more detailed breakdown.

First, it’s important to use the correct terminology. Cheesemakers don’t refer to these distinctive openings as “holes”; they call them “eyes.” These eyes are characteristic of Swiss cheese and are caused by a specific bacterial culture known as Propionibacteria, or Props.

Props are naturally present in hay, grasses, and soil, and they end up in raw milk when cows are milked. However, the pasteurisation process eliminates these bacteria, including Props. To ensure the formation of eyes in Swiss cheese, cheesemakers reintroduce Props into the pasteurised milk.

Once the Swiss cheese is produced and brined, the blocks or wheels are placed in warm rooms. This environment encourages the Props to produce carbon dioxide, which contributes to the formation of eyes and helps maintain the cheese’s texture.

Additionally, Props play a key role in giving Swiss cheese its distinctive nutty flavour and are crucial in several other cheeses related to Swiss cheese.

While we refer to it as “Swiss” cheese in the UK, the cheese made in Switzerland is known as Emmental. Other varieties like Baby Swiss and Jarlsberg are types of Emmental, with variations in moisture, fat content, and additional bacterial cultures.

Here are a few more interesting facts about Swiss cheese:

Do other cheeses have eyes too?

Yes, some other cheeses have eyes, but they are created by different bacteria or conditions. For instance, Gouda may have small, pea-sized holes. Various raw milk cheeses can also have eyes due to natural bacteria, though conditions might not always be optimal for their formation.

Does Swiss cheese always have eyes?

Not always. When Swiss cheese lacks eyes, it is considered a defect and referred to as “blind” Swiss. Despite the absence of eyes, the cheese will still have the same taste as traditional Swiss cheese.

How large can the eyes in Swiss cheese be?

The size of the eyes can range from that of a small coin to a larger coin. This variability in eye size makes Swiss cheese production quite challenging, as the USDA regulates the number, shape, and distribution of eyes.