Page:Popular Science Monthly Volume 58.djvu/160

152 sheep's milk, goat's milk, etc., differences in the handling of the soft curd, differences in the amount of salting and drying, differences in the temperature and moisture of the 'cheese cellar' all result in the growth of different kinds of molds and bacteria, producing variously flavored products. It is evident, too, that the character of the product will depend upon the abundance and varieties of the plants which furnish the flavor. Unless a dairy is supplied with the proper species of molds and bacteria, it is hopeless to expect the desired results. Here lies the work which the scientist must perform for the further development of the cheese industry.

The second type of cheeses, with which we are more familiar in this country, is the type of hard cheeses. These are not only of denser consistency, but they have commonly a less pronounced taste and odor and are not so suggestive of decomposition. They are, also, commonly made in much larger form, their denser nature making it possible for them to be made in very large sizes. They keep longer and are, therefore, much more generally exported into different countries.

The difference between the hard and soft cheeses, great as it is in the perfected article, is due to quite slight variations in the method of manufacture. The hard cheeses are made from curdled milk, curdled in just the same way as in the making of soft cheeses. But, after the curdling and the cutting up the curd to allow the whey to separate, the curd is broken up into small bits and placed in forms, where it is subjected to heavy pressure. Sometimes, immediately after the cutting of the curd, it is subjected to a moderate heat. For example, the Swiss cheeses are heated to about 110° Fahr. for a short time after cutting up the curd. This heating changes the nature of the curd somewhat and gives it a tougher and more elastic texture. In all the hard cheeses the curd is finally placed in wooden forms and then subjected to pressure, moderate at first, but soon increased until the pressure is quite high. This pressure converts the curd into a very dense, compact mass, and one in which microscopic plants cannot so readily grow.

But the hard cheeses require a ripening to develop the flavor as well as the soft cheeses, and the ripening is a longer and slower process. The pressed cheese is placed in rooms, or caves, or other locality where the temperature is not very variable or where it can, perhaps, be artificially controlled. Here it remains for weeks and frequently for months, during which time it slowly changes its chemical nature as a result of the action of the chemical or organic ferments, and simultaneously acquires the flavors which characterize the perfected product.

It is generally believed that the flavors here, as well as in the soft cheeses, are due to the growth of microscopic plants; but the subject has proved a very difficult one to investigate. Molds play little or no part in ripening the hard cheeses. Indeed, their growth is prevented by