A team of Swiss scientists has finally discovered the answer to a mystery close to their hearts: the reason Swiss cheese has holes.
The scientists at Agroscope, an agricultural research center, found that the holes are the result of hay inside the milk used to make the cheese, rather than from bacteria, as scientists previously believed.
The researchers explained to The Guardian that small bits of hay can fall into traditional milk buckets, which can cause holes in the cheese. Most modern cheesemaking techniques don't use traditional buckets, which eliminates the hay bits.
Before the new study, most scientists believed a 1917 study arguing that the holes were caused by milk bacteria releasing carbon dioxide during Swiss cheese production. But recent developments also side with the Agroscope team's findings — in the last 10 to 15 years, Swiss cheese has had fewer holes, as traditional milk buckets have been replaced by sealed milking machines.