MILK AND ITS PRODUCTS 193 



the stomach of calves that have been slaughtered for veal. 

 It is secreted by glands in the lining of the stomach in all 

 you ig animals that live on a milk diet. The casein as it is 

 coagulated by the rennet incloses the fat with it and forms 

 curt ,. This curd is cut into small pieces, and the water 

 gradually expelled by careful stirring and heating. When 

 the proper stage is reached, the curd is put into a press and 

 suff cient pressure is applied to cause it to unite into a solid 

 ma^ 3. When the pressing is completed, the cheese is put away 

 for ripening. Newly made cheese is not good to eat. It 

 lacks flavor as well as digestibility. It is kept for a period 

 of f 'om six weeks to six months for curing and ripening. 



The temperature of the curing room must be carefully 

 con- rolled, as too much heat will injure the quality of the 

 che( se. The difficulty of proper control of the ripening is 

 the most serious objection to making cheese on the farm, 

 and the greatest difficulty to be overcome, in operating a 

 factory in a climate subject to great extremes of heat. Dur- 

 ing 1 ;he ripening, the protein largely changes from an insoluble 

 to a soluble form and in this way becomes much more digesti- 

 ble. The typical flavor is developed at the same time. 



182. Condensed Milk. The process of condensing milk 

 was invented by Borden in 1856. For the year 1909 the 

 value of condensed milk in the United States was nearly 34 

 million dollars. The process consists in removing a portion 

 of the water from the milk by heating it in a partial vacuum. 

 The milk used must be fresh and in good condition. The 

 milk is condensed until 2J parts of the fresh milk make 1 

 part of the condensed. Two classes of condensed, milk are 

 commonly made. One is known as sweetened, since cane 

 sugar is added until the finished product contains 40 per 

 cent sugar. Condensed milk of this class is preserved 



