Lactose, or milk sugar, is less soluble than cane sugar and does not taste as sweet. It is the sugar which is used in baby foods. It is obtained from the whey left from cheese making after the casein and fat have been removed. The souring of milk is caused by the action of lactic bacilli present in the milk. The bacilli feed upon the lactose changing it to lactic acid, which acid reacts upon the casein, causing it to coagulate, or form a curd. In the large in- testine of the human body are found great numbers of bac- teria which feed upon the food residue present there, forming injurious compounds which are absorbed by the blood, with harmful results. The growth of some of these putrefactive bacteria is thought to be checked by the presence of lactic acid and by the action of lactic bacilli ; hence, sour milk is considered a healthful, as well as a nutritious food. The mineral matter in milk consists largely of the phos- phates and chlorides of soda, lime, and potash. Milk contains large numbers of bacteria. Few bacteria are normally present in fresh milk, but they enter the milk on account of the unsanitary conditions attendant upon 110 DOMESTIC SCIENCE milking and the subsequent care of milk. They reproduce very rapidly if the milk is not cooled. Typhoid fever, chil- dren's summer diseases of the intestines, tuberculosis, and other diseases are often traced to the milk supply ; con- sequently, the most cleanly conditions should be insisted upon by the health authorities, in the stable, the care of the cow, cleanliness of the milkers and of all utensils which hold the milk. Milk should be sold only in bottles which are filled and sealed at the dairy, the seal to be broken by the consumer only. EXPERIMENT 45. — Put a drop of cream on filter paper ; when dry, note the characteristic grease spot. This is a test for fat. EXPERIMENT 46. — Fill a tall cylinder with milk, and determine the specific gravity with a lactometer. EXPERIMENT 47. — Examine a drop of milk under microscope. Explain appearance and make a drawing of the fat globules seen. EXPERIMENT 48. — To \ c. milk warmed to 100° F. add \ of a rennet tablet dissolved in \ ts. water. Mix quickly. Let stand in a warm place until the milk clots. Break the clot lightly and put into a filter paper. Test the curd or casein for protein. (See pro- tein test, page 69.) EXPERIMENT 49. — Test the filtrate from above experiment with Fehling solution for sugar. BUTTER Butter is made by separating the fat globules of cream by churning, after the cream has soured from the action of bac- teria. COMPOSITION OF BUTTER (J. C. Olsen) FAT WATER SALT SUGAR 84% 12.8 % 2% 0.4% MILK AND MILK PRODUCTS 111 Butter fat is one of the most palatable, easily digested, and easily assimilated forms of fat. Its flavor is due to bacterial action. In the modern creamery all conditions are most sanitary ; bacteria which give a disagreeable odor and taste to butter are not present. Butter is artificially colored, but the coloring is harmless. Renovated butter is butter which has become rancid and is then subjected to a process of renovation, by which the disagreeable odors and flavors are removed. It is not an unwholesome product, but should not be sold at butter prices. Most states require that it be plainly marked " renovated " or " process " butter.

AI-modernized reading of the original text

Lactose, or milk sugar, is less soluble than cane sugar and does not taste as sweet. It is the sugar which is used in baby foods. It is obtained from the whey left from cheese making after the casein and fat have been removed. The souring of milk is caused by the action of lactic bacilli present in the milk. The bacilli feed upon the lactose changing it to lactic acid, which acid reacts upon the casein, causing it to coagulate, or form a curd. In the large intestine of the human body are found great numbers of bacteria which feed upon the food residue present there, forming injurious compounds which are absorbed by the blood, with harmful results. The growth of some of these putrefactive bacteria is thought to be checked by the presence of lactic acid and by the action of lactic bacilli ; hence, sour milk is considered a healthful, as well as a nutritious food. The mineral matter in milk consists largely of the phosphates and chlorides of soda, lime, and potash. Milk contains large numbers of bacteria. Few bacteria are normally present in fresh milk, but they enter the milk on account of the unsanitary conditions attendant upon milking and the subsequent care of milk. They reproduce very rapidly if the milk is not cooled. Typhoid fever, children's summer diseases of the intestines, tuberculosis, and other diseases are often traced to the milk supply ; consequently, the most cleanly conditions should be insisted upon by the health authorities, in the stable, the care of the cow, cleanliness of the milkers and of all utensils which hold the milk. Milk should be sold only in bottles which are filled and sealed at the dairy, the seal to be broken by the consumer only. EXPERIMENT 45. — Put a drop of cream on filter paper ; when dry, note the characteristic grease spot. This is a test for fat. EXPERIMENT 46. — Fill a tall cylinder with milk, and determine the specific gravity with a lactometer. EXPERIMENT 47. — Examine a drop of milk under microscope. Explain appearance and make a drawing of the fat globules seen. EXPERIMENT 48. — To 1 c. milk warmed to 100° F. add 1/2 of a rennet tablet dissolved in 1 ts. water. Mix quickly. Let stand in a warm place until the milk clots. Break the clot lightly and put into a filter paper. Test the curd or casein for protein. (See protein test, page 69.) EXPERIMENT 49. — Test the filtrate from above experiment with Fehling solution for sugar. BUTTER Butter is made by separating the fat globules of cream by churning, after the cream has soured from the action of bacteria. COMPOSITION OF BUTTER (J. C. Olsen) FAT SALT SUGAR 84% 12.8 % 2% 0.4% Butter fat is one of the most palatable, easily digested, and easily assimilated forms of fat. Its flavor is due to bacterial action. In the modern creamery all conditions are most sanitary ; bacteria which give a disagreeable odor and taste to butter are not present. Butter is artificially colored, but the coloring is harmless. Renovated butter is butter which has become rancid and is then subjected to a process of renovation, by which the disagreeable odors and flavors are removed. It is not an unwholesome product, but should not be sold at butter prices. Most states require that it be plainly marked " renovated " or " process " butter.

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