70 HOUSEHOLD BACTERIOLOGY 



septic action is so slight that food treated with the 

 minimum amount necessary for its preservation is not 

 unwholesome for adults in normal health. But in any 

 case food so treated should be plainly labeled with the 

 name and amount of the added preservative." 

 sugar Condensed milk keeps because most of the water 

 has been taken out and a large percentage of sugar 

 added. This results in a thick, pasty mass, enclosing 

 very little air, in which the few germs which survive 

 the heating that the milk undergoes cannot grow and 

 work. Decomposition is thus retarded or prevented so 

 long as the milk is not exposed to any fresh deposit of 

 dust. The contents of an open can will soon show 

 mold or give other evidence of spoiling and when di- 

 luted to the consistency of ordinary milk will sour like 

 fresh milk. 



Drying Fifty years ago the country housewives dried their 

 own apples, plums, raspberries and blueberries for 

 winter use. This drying of uncooked fruits is simply 

 an antiseptic measure and they must be kept dry or 

 they will spoil. They must also be carefully cleaned 

 before use. Some of the germs are killed by the dry- 

 ing process, but others enter the spore stage and are 

 ready for work when moisture is furnished. 



canned The present-day housekeeper owes much of the vari- 



60048 ety in her food supply to the possible preservation of 



fruits and vegetables through sterilization. "Canned 



goods" are sterilized by means of steam or boiling. 



The same process, of course, cooks the food, thereby 



