A team of scientists detailed what causes Swiss cheese to have its defining holes, contradicting previous explanations.

According to BBC News, the Swiss agricultural institute Agroscope said holes show up in the cheese because of "microscopically small hay particles" gathering in buckets used to collect milk. Past research suggested the answer had to do with bacteria that released carbon dioxide.

Agroscope concluded this happens among certain Swiss cheeses, like Emmental and Appenzell, because other makers have adopted different methods that cut down on hay particles making their way into pails. The study, which awaits peer review, is based on an experiment of turning milk into cheese with hay particles intentionally inserted in it.

Agroscope sought to explain why Swiss cheese was losing its "eyes," how the holes are referred to, over the past 15 years, BBC News reported.

John Jaeggi, a third-generation cheese maker with Swiss roots, told CNN hay particles are not all that can cause Swiss cheese to get its eyes. A researcher at the University of Wisconsin's Center for Dairy Research, Jaeggi equated the scientific reaction that occurs in cheese to how raindrops form, a "heterogeneous nucleation," he said.

"Rain forms around dust particles, and it's kind of the same principle," Jaeggi told CNN. "With these little specks of hay powder in that cheese body, that's causing weaknesses in the curd structure and then that's where the gas is going to form and get your eyes.

"[The Agroscope researchers] basically put the science behind what was commonly known."