This article is part of our co*cktail Chatter series, where we dive into the wild, weird, and wondrous corners of history to share over a co*cktail and impress your friends.
When it comes to Swiss Cheese’s distinct appearance, you may have heard folklore about its origins from your parents, including anecdotes like mice eating their way through the block or hungry workers sneaking a bite in factories long closed. Well, those stories are full of holes.
Cheese, essentially, is the product of a reaction between bacteria and milk. The bacteria typically set off a series of chemical changes that lead the milk to form solids called curds and a liquid called whey. The curds are concentrated to make up the solid product. Swiss cheese actually gets its defining holes from a type of bacteria not normally found in other cheese-making processes: Propionibacterium freudenreichii subspecies shermanii, better known as P. shermanii.
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During fermentation, the P. shermanii bacteria produces carbon dioxide, creating air pockets that blow up the inside the cheese like a balloon. Since Swiss cheese is fermented at warm temperatures, it’s very malleable, and the gas bubbles can expand and form large circles in the cheese. The cheese is kept at 70 degrees Fahrenheit for four weeks for its signature large holes to form. When the process is finished, it’s cooled down and the holes — or “eyes” as they’re called in the industry — are solidified. While other countries make cheeses with similar flavor profiles like Fontina and Gruyère, it can’t be considered Swiss cheese unless it has the properly formed eyes.
In the early 2000’s, cheese experts were starting to notice that the holes were slowly disappearing over time, causing great concern over the future of Swiss cheese. The defective cheese without the eyes was called “blind Swiss” and could not be considered real Swiss cheese. Scientists set out to determine the root of the issue, and in 2015 they found that the modern, sterilized cheese-making environment was restricting the formation of holes.
It turns out that hay dust that would float around the barns of cheese makers is essential to the formation of the holes. The old, open-bucket methods would allow the plant microparticles into the process, contributing to its bacterial milieu. The scientists found that when they added hay dust to the modern cheese production, the cheese’s iconic holes were restored.
So, next time you see a quintessential block of Swiss cheese, you can actually thank hay dust for its picture-perfect appearance.
*Image retrieved from Sunny Forest via stock.adobe.com
Published: December 19, 2023
