The mystery of Swiss cheese and its disappearing holes has been solved – the milk is too clean.

Swiss cheese holes mystery solved.

Swiss cheese holes mystery solved. Image by Patrick Hoesly / CC BY 2.0

A Swiss agricultural institute discovered that tiny pieces of hey dust are responsible for the famous holes in cheeses like Emmentaler or Appenzeller.

As milk matures into cheese these “microscopically small hey particles” help create the holes in the traditional Swiss cheese varieties.

The Swiss government-funded Agroscope institute said in a statement that the transition from age-old milking methods in barns to fully-automated, industrial milking systems had caused holes to decline during the last 15 years.

In a series of tests, scientists added different amounts of hey dust to the milk and discovered it allowed them to regulate the number of holes.

(Press Association)