PRODUCTION AND INSPECTION OF MILK I. Of all substances consumed as food the position of milk is unique. And of course in the northern temperate latitudes when we speak of milk one naturally understands that cows milk is understood. It owes its unique position to the following circumstances as pointed out by Rosenau: (1) It is the only standard article of diet obtained from animal sources that is ordinarily consumed in its raw state; i.e., it is not ordinarily heated in some cooking process prior to consumption.
(2) Its peculiar composition renders it highly suitable as a medium for a wide variety of micro-organisms, both pathogenic and non-pathogenic.
(3) The foregoing characteristics subject milk to rapid changes as a result of the activity of the micro-organisms, some of which may produce decompositions that render the milk unfit or even dangerous as food. As a consequence of these decompositions the original character of the milk may be largely lost or markedly altered.
(4) The conditions of the production and the activity of micro-organisms make milk the most difficult of all animal foods to obtain, to handle, to transport and to deliver in a clean, fresh and satisfactory manner.
These peculiarities serve to indicate the important relation ship which milk possesses to both health and disease. Thus: (1) As a result of the favorable environment it creates for micro-organisms, it may serve as an important route for the dissemination of several species of infective agents; (2) Devised as it is by nature as the first food for the calf, it serves nearly equally as well as food for the young of the human species as well as for human adults, due to the proportion in which the different food elements are present. But on the other hand, when its composition is altered by microbial activity arising from, improper care, it may become a dangerous instead of a safe food; (3) In addition to possessing all the different food elements in its composition, the elements are present in proper relative proportions, so that milk may be said to be the only properly balanced food. Furthermore all the different sub stances present are readily digestible. If one tends to tire
of a milk diet, the monotony may be relieved by some of the numerous modifications which the cook or housewife may devise.
2. Sophistication of Milk.—Unscrupulous dairymen the world over make a more or less frequent practice of altering the milk they retail, either by abstracting the more valuable con stituents, such as the butter fat, or by adding diluents or en deavoring to conceal changes of decomposition, or to prevent decomposition by improper methods. Under these headings come the practices of skimming, watering, adding of skimmed milk, thickening, coloring and the addition of alkalies or of chemical preservatives.
These practices are unjustifiable and fraudulent, but since the health of the consumer is as a general rule unaffected, though his pocket book is depleted by fraud, we must regard this question as of economic importance rather than of sanitary importance. The only situation where the health of individuals might suffer as a consequence is in situations where milk of a certain composition is desired, as for example, for the feeding of tuberculous patients or of infants, with whom it would consti tute the principal article of the diet.
3. Source of Micro-organisms in Milk.—The hygienic im, portance of milk is closely related to its microbial content, not that the myriads of micro-organisms which thrive in milk are in themselves necessarily harmful, but rather the extent of their abundance gives important information relative to the age of the milk, the degree of care exercised in its production and handling, and the conditions under which it has been stored. It must be borne in mind that an exact or even a fairly close approximate determination of the number of bacteria per unit volume of milk cannot be secured, and that the best re sults are only in reality approximations. Furthermore the enumerations secured vary with the technic employed. An exposition of these phases of bacteriologic procedure would be too extensive for presentation here, so reference must be made to other sources of information.