Grades or Classes of Milk.— The present tendency is toward the division of milk and cream into grades, primarily upon its sanitary quality. The grades established in New York city will illustrate the general divisions into which market milk is placed: (1) Grade "Ax' - For infants and children. Raw: Cows tuber culin tested and free from all diseases; bacteria not more than 30,000 for milk and 150,000 for cream when delivered to the consumer or at any time prior to such delivery; employees free from all communicable diseases or disease germs; delivered to consumer within 36 hours after production. Pasteurized: Cows healthy, as determined by physical examination at least Once eft& year; 'bacteria content not 'to exceed 11 t t t before'pasteurization and not more than 30,111 for milk and 150,000 for cream when delivered to consumer or at any time after pasteurization; employees free from communi cable disease or disease germs; delivered to consumer within 36 hours after pasteurization; (2) Grade "B))— For adults (pasteurized). Cows in good health as determined by physical examination at least once each year; must not contain more than 1,503,000 bacteria before pasteurization and not more than 100,000 for milk and 500,000 for cream when delivered to consumer or at any time after pasteurization; employees free from communicable disease or disease germs; milk delivered to consumer within 48 hours after pasteurization, and cream within 72 hours; (3) Grade "C"--- For cooking and manufacturing purposes. Milk or cream not conforming to all the requirements of the subdivisions of Grade A or Grade B, and which has been pasteurized, according to the regulations of the Board of Health, or boiled for at least two minutes. This milk must come from healthy cows, as determined by physical examination at least once each year; bacteria content must not be excessive; milk delivered to consumers in cans only, 48 hours and cream within 72 hours after pasteurization. Same requirements as to health of employees as for Grades A and B. In addition to these requirements certain other regulations must be observed for each grade. In the case of each of these grades, the container must bear a dis tinct label, approved by the Board of Health, indicating the grade and no other statement or designating mark.
Certified milk Is milk produced under the supervision and in conformity with the ments of a medical milk commission appointed' by the local county medical society. This milk must conform with very rigid regulations laid down by the commission, which insures this grade of milk being of a very high standard of composition and sanitary excellence.
Butter.— Butter is the fat of milk which has been separated from most of the other con stituents by the process of churning. In mod ern dairy practice the cream is removed from the milk by centrifugal force, by means of the cream separator, this being possible because of the fact that the fat globules are lighter than the other constituents of the milk and are thrown out as the milk passes through the rapidly revolving bowl of the separator.
Bulletin 149 of the United States Depart ment of Agriculture gives the following com position for butter: Variations in the composition of individual lots of butter are frequently much greater than those indicated by these averages. This is shown
by the following: There are two common types of butter, known as sweet, cream and sour cream butter. The sweet cream butter is made from cream in which lactic acid has not been allowed to velop. It has a mild flavor which is desired by many persons, and may be made from either raw or pasteurized cream. Sour cream butter is made from cream in which lactic acid has been allowed to develop, resulting in a product with a more highly pronounced flavor. This is the standard type of butter in America and in most• countries of Europe. The production of good butter of uniform quality and high flavor requires the use of cream which has been pro duced and handled with care, cleanliness being a first essential in the making of good butter, After the clean, sweet cream is obtained, the next step is the development of the proper degree of acid or the "ripening* process. This is brought about by the action of certain forms of bacteria commonly known as the lactic acid bacteria (Batt. lactis acidi), which work on the milk-sugar, changing it into lactic acid. It is during this ripening process that the character istic flavors and odors of the butter are de veloped, the final flavor depending upon the kinds of bacteria which take part in the ripen ing and the degree to which fermentation is allowed to develop. The finest qualities of the butter may be lost by the over-ripening of the cream. Cream may be ripened by the action of the lactic acid bacteria normally occurring in it or the process may be hastened by the use of a "starter? which is a pure culture of the lactic bacteria grown in skimmilk or buttermilk. In man ,y factories the cream is pasteurized before the starter is added, thus destroying most of the miscellaneous bacteria in the cream and making it possible to more completely control the nature of the ripening process. pur pose of churning is to remove the butter-fat from the milk serum and bring the fat globults into compact form. This is done by placing the cream in a churn of such form that when it is revolved slowly the cream is thoroughly agitated, thus bringing the minute fat globules in contact with each other and causing them to adhere as a result of the concussion. The ease with which cream will churn is influenced by many factors, but chiefly by the richness of the cream, the temperature and the speed of churn. When a sufficient number of fat glOb tiles have coalesced to form visible granules, the butter has °come? The churning process may be controlled to give granules of any de sired size. After the churning has been com pleted, the buttermilk is 'drawn off and the butter washed with cold water to insure the further removal of the buttermilk and to firm or harden the butter-fat, so it can be more easily handled. The wash water is then re moved, the desired amount of salt added and the butter worked' enough to give an even dis tribution and thorough incorporation of the salt. It is now ready to be packed in tubs or made into prints, depending upon the market to which it is to be sent. The butter markets recognize certain fairly definite grades known as extras, firsts, seconds and thirds.