Gone are the days of semi-scientific guesstimation and old wives' tales about hungry mice: after nearly 100 years of research, Swiss scientists have found the true culprit behind the iconic holes in Swiss Cheese.
Turns out, it's itty bitty pieces of hay.
Agroscope, the Swiss agricultural institute that made the discovery, determined the traditional method of gathering milk via open-air bucket allowed microscopic particles of hay to fall in, which in turn caused the creation of holes as the milk matured into cheese. Consequently, the switch to modern milk extraction methods over the past 10-15 years has all but eliminated the inclusion of these hay particles, leading to Swiss cheeses like Emmental and Appenzell having fewer holes -- or in some cases, none at all.
The Swiss scientists proved that by altering the amount of hay particles present in the milk prior to maturation, they could artificially manipulate the amount of holes present in the final cheese product. They have yet to determine the cause of holes in donuts, bagels, and SpaghettiOs, however. But if you love the idea of eating food with holes in it (and really, who doesn't?), this is probably the best news you'll hear all day.