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How does cheese get holes?

A world-wide favourite, the mild flavour as well as their unique appearance has made Swiss cheese one of the most popular choices for cheese lovers for centuries. But one question that has been debated by scientists for many years, how does Swiss cheese get its distinctive holey appearance?

Contrary to the stories we were told as children, the holes are not in fact a result of mice chewing through the delicious cheese. Here we explore the theories that aim to explain how Swiss cheese gains its holes.

Swiss cheese

Is it bacteria?

A theory into how these holes are made was put forward in the early 20th century by William Mansfield Clark, a chemist from the Department of Agriculture. Clark theorised that during the aging process a particular bacteria, unique to Swiss cheese, emits carbon dioxide which produces bubbles which subsequently pop, resulting in the holes seen within the cheese.

For over 100 years this theory was widely believed to be true by cheese aficionados across the globe, however in 2015 scientists from a Swiss laboratory announced that they had made a discovery that could answer this age-old question.

Is hay the answer?

Scientists working at Swiss agricultural institute, Agroscope, now believe that the holes are formed by very small pieces of hay that fall into buckets of milk when they are collected in barns. Over time, these pieces of hay cause holes in the cheese as it ages by weakening the curd’s structure, which in turn allows gas to form and create the holes, or ‘eyes’ as they are commonly known.

The discovery was made with the help of a CT scanner, which tracked the aging process of the cheese for 130 days. This discovery also provides evidence as to why you may see less holes in Swiss cheese as you would have many years ago. This is due to the fact that milking methods have been modernised, making them more hygienic and therefore less hay particles fall into containers.

Swiss cheese is one of our most popular cheeses we sell here at JS Bailey. Is your business fully stocked? Place your order of Emmental or Edam here.