Why does Swiss cheese have holes?


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From a sandwich topping to an ingredient in tortillas, Swiss cheese is a favorite of many cheese lovers. The food is also different from many other cheeses thanks to its holes, but why exactly does Swiss cheese have holes?

Carbon dioxide created during manufacturing is said to be what causes the holes in Swiss cheese, but there could be another theory.

Most resources posit that the bacteria are created during the manufacturing process. Due to the starter used to make the cheese and the temperature at which the wheels are stored, bacteria develop over time and create bubbles of carbon dioxide. Eventually these bubbles burst and that is what makes the holes.

While that was the prevailing theory, recent science points to a different reason. Agroscope, a Swiss agricultural institute, believes that the hay could cause the bubbles. Cheese made from cubes in barns is likely to have hay particles inside. The hay then causes a structural weakness in the curd where gas can form and then create holes.

However, over time, Swiss cheese holes have become less and less frequent. Technological updates and more sanitary production methods mean fewer hay particles in the milk and fewer holes in the cheese. While it will still taste the same, is Swiss cheese really Swiss cheese without the characteristic holes?

The next time you’re making a sandwich and want to toss in some Swiss cheese, make a note of those holes. There may be less next time.