The old method of adulterating milk with water has very largely gone out of practise, owing to the surveillance of city authorities, and the passing of laws that fix legal standards, which require milk to contain a certain percentage of fats and total solids.
Evil of milk preservatives
The chief form of criminal tampering with milk has been the use of preservatives to prevent souring. Formaldehyde has been used very extensively for this purpose. Formaldehyde is a poison, destructive to all cell life, and has probably been the cause of more actual deaths than any other form of food adulteration.
MILK PASTEURIZATION
Pasteurization, which takes its name from Pasteur, the French bacteriologist, is merely a process of heating milk to about 170 degrees Fahrenheit for the purpose of destroying possible dis-ease germs, and the bacteria that produce fermentation. In this process the milk is not allowed to come to a boil for the reason that boiled milk is rather "dead" or distasteful, and would readily be detected by the public. It is quite evident that any method of Pasteurization, which would kill bacteria, would also cause coagulation of the protoplasm and the albumin of the milk, and render it much less nutritious, and much more difficult to digest.
Virtue of naturally soured milk
If milk producers and dairymen understood the superior food and remedial value of naturally soured milk, and would exert some effort to educate the public in its use, they would soon establish a new and profitable industry, and would give the dairy business of the whole country a new commercial impetus. The souring of milk can be prevented by cleanliness, which renders Pasteurizing unnecessary. At the time of the Paris Exposition, a dairy farm in Illinois sent pure unpasteurized milk to Paris, which arrived in an unsoured condition. This was achieved by absolute cleanliness, with the cows, dairy utensils, etc.
CHEESE
Cheese consists of the coagulated casein of milk, together with the fat globules that may be mechanically retained. Cheese is made by coagulating the milk with rennet, which has been extracted from the stomach of a calf, the sugar of the milk being passed off in the whey, and lost.
Schmier Käse or cottage cheese is formed by allowing the milk to sour, and to coagulate by gradual warming. This cheese is usually made from skimmed milk, hence contains practically no fat.