PREPARATION OF MILK AND MILK PRODUCTS

Pasteurization of Milk

In pasteurizing milk it is heated to a temperature of 60° C. (140° F.) for a period of twenty minutes. This destroys the so-called pathogenic germs, yet does not destroy the ordinary milk ferments. It does not change its digestibility nor alter the taste or appearance.

All of the so-called pathogenic germs, such as tuberculosis, typhoid, dysentery and diphtheria, for example, are completely destroyed by pasteurization, but the ferments are not destroyed and the milk is in no way altered. This process may be accomplished on a large scale and thus furnish as safe milk for commercial consumption. Pasteurized milk should be rapidly cooled after heating, and if kept cool furnishes a clean, healthy milk entirely safe and satisfactory for infant food as well as for adults.

Pasteurization furnishes a purified milk but not a pure milk. It is undoubtedly the best means of preservation and may be considered as bearing the same relation to purification of milk as filtration bears to purification of water.

The use of formaldehyde, borax and boracic acid is as objectionable in artificial preservation of milk as in the preservation of meat and other foods and should not be tolerated.

Condensed Milk

Milk is condensed by removing some of the water. It is made either from skim or whole milk. It may be unsweetened or sweetened with cane sugar. Condensed and evaporated milk should contain a label stating the grade of milk used. Condensed and evaporated milk are poor in vitamin C.

Dry Milk

It has been found that by certain processes it is possible to dry milk, taking all the water out and leaving a powder. This may be accomplished and still retain most of the nutritive value of the milk. Vitamin fat soluble A and water soluble B remain practically the same, but water soluble C vitamin is diminished. Babies fed on dried milk will thrive, but orange juice or some other food containing antiscorbutic properties must be given to compensate for the loss of vitamin C. Dried milk provides an adequate supply to many parts of the country and to the cities, where it is difficult to obtain fresh milk.

Butter

Butter is produced by placing cream in a proper apparatus and agitating or churning it until the fat globules coalesce into lumps. These lumps are then taken out of the serum known as the buttermilk and the water and milk worked out until it becomes more or less solid. When butter has had the milk and water worked out of it the constituents should be in about the following proportions: Fat, 83.5%; curd, 1.0%; ash, 1.5%; milk sugar, 1.0%; water, 13.0%. By weight butter should never contain more than 16% of water and should contain at least 80% of fat.

Owing to the conversion of the fat into fatty acids butter will, in the course of time, become acid, rancid and unfit for table use.

Oleomargarine is a product resembling butter. It is manufactured from animal fats and vegetable oils. It is not as desirable an article of diet as butter. It contains margarine fat and only .5% of the volatile fats, while butter fat contains about 8%.

Oleomargarine may be distinguished from butter by boiling. Butter boils more quietly and a foam is formed on top, while oleomargarine sputters much like oil mixed with water and there is little or no foam produced.

Cheese

Cheese is manufactured from skim milk, whole milk, or milk to which cream has been added. The more cream the richer is the product. Coagulation of the milk is accomplished by adding rennet; the curd is then pressed to expel the whey; next it is placed in molds and kept in a cool place to ripen. After cheese has been properly ripened it makes an excellent article of diet. It contains a large proportion of nitrogenous substances. There are many grades of cheese, the quality depending not only upon the process involved in the manufacturing, but also upon the richness of the milk from which it is made.