Donn Sinclair  age 12, Westbrook  Maine:

What makes the holes in Swiss cheese?

The mystery is how do those round bubbles get right inside the solid cheese? The answer is, they are made by tiny bacteria that lived with it the cheese. Cheese is made from milky These bacteria live, breathe and feed on the sugar in the milk. In the process, they turn the milk into cheese and give off waste gases. The cheese hardens as it ripens. The waste gases given off by the little bubble blowerss collect together and push round holes in the ripening cheese. The cheese sets around the bubbles, leaving the empty holes to appear when we slice into it.

The dairy farmers of Switzerland thought that anybody could make Swiss cheese from their recipe from any milk anywhere in the world. Some 80 years ago, some of them went to Germany to make it. The pasture was good and the cows thrived, The cheese makers made cheese. But the old recipe did not work, The ripe cheese was not firm enough or the right flavor. Worse of all it was riddled with tiny slits instead of beautiful round holes.

The new German cheese was certainly not Swiss cheese. But it was good, People enjoyed it and named it Tilsit cheese. Then the experts tried to find out why Swiss cheese could be made only in Switzerland. They suspected our bacteria friends. There are countless varieties of bacterium in all milk. The dangerous ones are destroyed when milk is pasteurized. But plenty of the friendly microbes remain.

The milk in Switzerland it seemed, contained a certain bubble‑blowing microbe that was not there in the German milk. The little fellow was finally tracked down! isolated and given a fancy name. The bacterium that blows the round bubbles in Swiss cheese is called Propionibacterium Helveticum. That's when you consider that it takes some 25,000 of the tiny things to measure one inch&

The little bubble‑blower was isolated, fed and pampered. He grew and multiplied. Quantities were packaged and sold to cheese dairies, When the right amount was added, the old Swiss cheese recipe worked every time, Now at last, anybody can make Swiss cheese from any good milk anywhere in the world.

The first step is to curdle fresh whole milk with a sort of junket powder„ Then the curds are cut very fine with special knives. An exact amount of our bacteria is added either to the milk or the curds, The curds are drained in wooden boxes lined with cheese cloth, They settle to form a big cheese which is rubbed in salt or steeped in brine and then coated with wax, The cheese is carefully watched and left to ripen, maybe for six months. Inside, the little bacteria are living, eating, multiplying and busily blowing their bubbles. Their work is done when the delicious cheese is ready to be eaten,