BUTTER, a product of milk,' particularly cow's milk, consisting chiefly of its fatty con stituent. It is obtained by churning or other wise violently agitating milk or its cream, and working the product to remove water and other constituents. Butter fat is not a simple fat, but is a mixture of several fats, which are indi vidual compounds of glycerine and several dis tinct fatty acids. The principal fats in butter are olein, which constitutes 35 per cent; pal mitin, 26 per cent; and myristin, 20 per cent. Launn, butyrin and caproin are present in much smaller proportions, and there are also very small percentages of caprin, stearin, capry lin and other constituents. It has a specific gravity of 0.91 and a melting point of about 92° F.
Butter has been in use from early historic days. It is first mentioned in the Bible in Gen. xviii, 8. It was used as food and medicine, as an ointment and for burning in lamps. The Greeks probably learned of it from the Scy thians or Thracians, and the Romans from the Germans. It was made from the milk of sheep and goats, and later of cows, the method of making being to jar the milk roughly by placing it in skin bags or pouches hung over the backs of trotting horses. Formerly butter was pre pared by direct churning of the whole milk; this was both laborious and wasteful of butter fat. To reduce labor and loss the system of setting the milk and skimming off the cream was evolved; since 1877 this method has given way in considerable measure to the use of cen trifugal force for the separation of the cream and milk.
The making of good butter begins with the cow. She must be healthy and be well fed. The essential next in importance is absolute cleanliness in the care of the milk. The dairy utensils should be of tin, and never used for any but dairy purposes. They should not be continued in use after the tin plating begins to wear off. They should be washed with a brush, never with a cloth, and with hot water and sal soda or borax, and not with soap. The final rinsing should be with boiling water, after which they should be drained and allowed to dry without wiping. The process of making butter is divided into the operations of cream ing, churning, working and finishing. The fat exists in the form of small globules in the milk, in suspension. In the setting system the milk is placed in shallow pans about four inches high, or in deep ones of about 18 inches, and advantage is taken of the fact that the fat globules, being lighter than water and other constituents of the milk, rise to the surface by the action of gravity. Large fat globules will
rise more rapidly than small ones, and the size of the globules varies with different breeds of cattle. In the milk of Jersey cattle they are 1/8000 of an inch in diameter; in Holstein cat tle 1/12000 of an inch in diameter. In the shal low-pan system the milk is set as soon as pos sible after it is drawn, and the cream is skimmed off in 24 to 36 hours. This system is wasteful in that the skim-milk often contains 0.5 to 1.5 per cent of fat. The deep-setting system is less wasteful, the fat in the skim-milk being often reduced to 02 per cent. The new-drawn, warm milk is placed in cans surrounded by or submerged in water of about 40° F., and the rapid reduction in temperature causes the glob ules to rise quickly. It is best to skim the cream at 30 to 40 lactometer: that is, 10 gallons of milk should yield 1 to 15.5 gallons of cream. The cream is removed by dipping it off, or the skim-milk is drawn off from the bottom of the can. The fat left in the skim-milk consists of the smallest fat globules.
The introduction of the separator and use of centrifugal force has resulted in a more per fect and rapid separation. This force exceeds that of gravity a thousand-fold. The system of separation is continuous, a constant, uniform Bow of milk being conducted into a bowl or drum revolving at from 5,000 to 9,000 or more revolutions per minute. The inlet tube is in the centre of the bowl and reaches almost to the bottom; here the constituents in the milk sepa rate, the heavier serum gravitating to the cir cumference of the bowl, the fat—the lightest portion — remaining in the centre. These are forced upward by the incoming milk, and the separated milk escapes through a side tube, while the cream passes through a small outlet in the centre. This last outlet can be closed or opened in some machines, thus regulating the percentage of fat in the cream. The ma chines are of various sizes, from those worked by hand power and doing 200 to 500 pounds of milk per hour, to power machines of 2,000 pounds and over per hour capacity. Some makes have appliances within the bowl to in crease the efficiency. A good separator, well run, will not leave more than from 0.05 to 0.1 per cent of fat in the separated milk. The temperature should be kept between 85° and 95° F. for the best results and the speed should not lag.