Swiss scientists have finally discovered the mystery of the holes in Swiss cheeses like Emmental and Appenzell .
Children would think the holes are caused by mice nibbling away inside cheese wheels, but the recent discovery after centuries of study clears up the matter.
Experts previously thought that the holes are caused by bacteria, according to Discovery News. But the study from Agroscope, a state center for agricultural research, said the phenomenon was caused by tiny bits of hay present in the milk. It was found that with modern cheese-making methods, in which the milk is cleaner, the holes would become smaller or would disappear, Business Insider reported.
"It's the disappearance of the traditional bucket" used during milking that caused the difference where bits of hay fell into it and caused the holes, said Agroscope spokesman Regis Nyffeler.
Agroscope said that the phenomena had been studied since 1917 when American William Clark published a detailed report concluding that it was caused by carbon dioxide released by bacteria in the milk, according to MSN News.
It was noted by the Agroscope scientists that over the past 10 to 15 years, Swiss cheeses had fewer holes since open buckets were replaced by sealed milking machines. Hence, the milk is completely free of hay.