Milk - cream, fat, solids, water, lactic, care, percentage and color

MILK. The value of milk as an article of food is clearly shown by the fact that it is sufficient to support, and to increase the growth of, the young of every species of mammalia. Examined by a microscope, it is seen as a transparent fluid in which float numbers of extremely minute transparent globules, consisting of fat surrounded by an albuminous envelope—its whitish, almost opaque appearance is an optical illusion.

Cow's milk—which is in this country exclusively understood by the general title of "milk," though in some parts of the world the milk of goats, ewes, mares and various other animals forms an important part of the human diet—varies in compo sition from 84% to 90% water and 10% to 16% "solids." The solids include from 2% to 7% fat, to casein, 2% to 6% sugar, a small amount of albumin, and small quantities of "ash" or salts of various kinds.

The Fat when extracted is what we know as Butter. The Casein, is the main principle of Cheese. The Sugar, or "lactose," has the same chemical composition as the ordinary sugar of commerce, but is not so sweet.

The law generally requires from 3% to fat, and 8% to 9% of other solids. U. S. Standard Milk contains not less than of solids not fat, nor less than of milk fat. Some milks will reach a fat percentage of 10%, but this is very unusual, the amount rarely ex ceeding 7%. The mixed milk of a large cream ery seldom goes above 5% or below 3%.

Pasteurized Milk is milk that has been heated—below boiling but to a degree suf ficiently high to kill all pathogenic bacteria—and immediately cooled to 50° Fahr. or lower, to retard the development of any remaining organisms.

Sterilized Milk is milk that has been heated to the temperature of boiling water, or higher, and held at that point long enough to kill all organisms present, or that has been repeatedly pasteurized.

Modified or Blended Milk is milk modified in its composition so as to have a defi nite and stated percentage of one or more of its constituents.

Cream is milk containing a large percentage of the fat globules, generally from 15% to 25%. It is obtained by centrifugal separation or by permitting the globules to rise by leaving the milk undisturbed for a number of hours.

Skim Milk is that from which a part or all of the cream (fat) has been removed. U. S. Standard Skim Milk contains not less than of milk solids.

"Sour Milk" is the result of the formation of lactic acid by the development of lactic bacteria (see article on BACTERIA) . In spite of the general prejudice against it,

it is a thoroughly wholesome drink, for the lactic acid prevents for a time the action of other bacteria which would speedily bring about putrefaction. In Europe, milk is commonly soured in cellars for use, especially in summer, as a popular and refresh ing beverage.

Buttermilk (which see) is the product that remains when butter is removed from milk or cream in the process of churning.

Milk Tests.

Generally speaking, pure milk is of a slightly yellowish-white color, with little or no odor, and of a distinctly sweet and fresh taste. If allowed to stand for several hours, cream should rise naturally and should form from one-eighth to one-fifth of the total volume, and no sediment should be left in the vessel. In "rich" milk the proportion of cream may be as high as one-quarter. When poured from a tumbler, the milk should cling to the glass a little instead of running off clean like water.

Artificial coloring generally consists of annatto or coal-tar dyes. If any erable quantity is used, its presence can generally be detected by noting the ance of the milk when the cream has risen in the bottle. The natural color of milk is confined largely to the cream and there is consequently a noticeable difference between the color of the pure cream and that of the milk below it—the latter sents a bluish tinge. Artificial colors will generally tint also the milk below the cream. There are several instruments in use to detect adulteration and ascertain the comparative richness of milk, prominent among them being the LACTOMETER and the BABCOCK TEST ( which see), but trained judgment is necessary to obtain conclusive results because of the variation in milk from different sources and at different seasons.

Care of Milk.

Milk should be kept at a low temperature, below 50° Fahr., and apart from all articles of strong smell. Every receptacle employed in handling it should be scrupulously clean. The necessity for absolute cleanliness in its care should be impressed particularly upon those who have the care of children.

Many glass jars are sent to the grocer's for milk with a dingy coating on the inside—this is inviting sickness. Glass receptacles of any kind which have held milk, should be first thoroughly rinsed in cold water and then washed in hot water to which a little ammonia has been added.