72 THE CANNING OF FOODS. 



The milk is run through a clarifier to remove any foreign mate- 

 rial not taken out by the home strainer. It is next drawn into a 

 large tank which will hold an amount sufficient to charge the pan. 

 The milk of several herds is mixed in order to secure uniformity 

 in the fat content. Each tank is tested for fat and solids so that 

 the exact ratio of concentration needed to give a certain result may 

 be known. The milk is given a preliminary heating, usually to 

 190 F., though there may be some variation in the different plants. 

 The milk is then ready for the vacuum pan, which consists of a 

 large copper kettle completely hooded and connected at the top 

 with a pump. The milk is heated in this kettle by means of a coil 

 on the inside. The pump draws a vacuum of 25 to 29 inches and 

 evaporation with violent agitation takes place at 130 F. ; the tem- 

 perature is usually kept below 150. When the batch is nearly fin- 

 ished, a " strike " is made or a sample is drawn to test the consistency. 

 The milk may or may not be run through a homogenizer to divide the 

 fat into such fine particles that the cream will not rise in the finished 

 product. It is next drawn into a filler, and in so doing the tempera- 

 ture may be raised to about 165 or 170 F., or the can may be filled 

 cold. 



The processing is done in retorts which differ from those used 

 in vegetable packing in that special crates are provided which carry 

 the cans and revolve so that the contents will be kept in a smoother 

 condition. Both the time and temperature for condensation vary 

 in different factories, and in careful work tests are made on a few 

 cans before the batch is processed. In general it may be said that 

 the temperature varies from 225 to 240 F., the time depending upon 

 the degree of condensation desired, the condition of the milk, and the 

 size of the can. Twenty minutes for a 6-ounce and 28 minutes for 

 a 12-ounce can at 240 F. is safe. Immediately at the close of the 

 cooking the cans are cooled, placed in cases, and shaken for three 

 minutes. 



Condensed milk can not be used for all the purposes of fresh 

 milk, and is somewhat less digestible than the fresh on account of 

 the cooking. It is an excellent substitute for many purposes and 

 the evaporated that is, the unsweetened product has the advantage 

 of being sterile. 



SPECIALTIES AND SOUPS. 

 BEANS, BAKED. 



Pork and beans, beans and tomato sauce, and baked beans are 

 the ways which the labels read on the product which a few years ago 

 was known only as " baked beans." The beans used for this purpose 

 are the small white pea or navy bean. They are chiefly grown in 

 New York, Michigan, and Wisconsin and are a regular field crop, 



