PRESEEVING FOODS 215 



Certain kinds of wood smoke give the best flavor, 

 though any wood may be used for the purpose. 



Cold Storage. Putting foods in cold storage does 

 not kill the bacteria, but it keeps them from grow- 

 ing and multiplying. As soon as the temperature 

 rises, they begin to act and the food soon spoils. 



Preserving Fruits. Sugar is used somewhat in 

 curing meats and very extensively in preserving 

 fruits. When fruits are cooked for a long time the 

 *^ boiling down'' kills all germs and drives off the 

 water so that other germs can not grow. 



Souring of Milk. It is also germs that cause milk 

 to sour. The air contains many germs, the dust of 

 the barn is full of them, and there are some on the 

 milk pail and on the hands of the milker. So it is 

 impossible to keep germs from milk. All milk cans 

 should be scalded after using and, if possible, placed 

 in the sunlight, which is a powerful enemy of germs , 



Bacteria in Butter and Cider. Germs or bacteria 

 make butter rancid. This can be prevented by. 

 working out of the 'butter all the milk and water 

 wliich bacteria need to thrive and by thoroughly 

 mixing salt into it. It is bacteria that makes cider 

 turn sour and ferment. The solid, slimy mass known 

 as the ** mother of vinegar" is merely a vast colony 

 of bacteria. Sweet cider makes the best vinegar 

 because it contains more sugar for the bacteria to 

 work upon. The process of making vinegar from 

 new cider may be hastened by introducing some 

 ** mother of vinegar.'* 



