The Preservation of Food in the Home. — Part I 1263 



day give rise to life, is subject to those changes that may be called, for 

 lack of a better term, life processes. 



When the canned food of olden times kept, it was not because air had 

 been removed but because all life processes, both in the food and in those 

 small organisms that may have been on it or in it, had been destroyed in the 

 cooking process and further entrance of more organisms had been pre- 

 vented by keeping the food in air-tight cans. The presence of air in a 

 can will not cause food to spoil, provided the air is sterile — that is, pro- 

 vided it has been freed from all living organisms. A half -filled can of 

 fruit will keep perfectly if the fruit, can, rubber, and cover are sterile, if 

 the air space above the fruit is sterile, and if micro-organisms cannot enter 

 the can. The precaution sorhetimes taken to run a knife or a spoon 

 down the sides of a can to remove the few bubbles that may be there, is 

 therefore not necessary. Unless the spoon or knife has been boiled, its 

 use in removing air may even endanger the keeping qualities of a can of 

 food, for the spoon or knife may hold organisms that thus find their way 

 into the can. 



It is small wonder that our grandmothers believed the oxygen theory, 

 for in those days little was known about the processes that cause fruits 

 to ripen and decay and nothing at all was known concerning the minute 

 living organisms that cause food to spoil — organisms so small that they 

 cannot be seen by the naked eye, but must be magnified many times by 

 a powerful microscope before they become visible. The microscope had 

 not been developed in the days of our grandmothers; it is only since the 

 advance of science has perfected it that we have had knowledge of the 

 organisms called micro-organisms. 



Although we are unable to see a single one of the mold plants, yeast 

 plants, or bacteria that may live on our foods and cause them to spoil, 

 yet we are very familiar with products of their growth and in some cases 

 with the colonies that they form when many millions of them have grown 

 and accumulated in one place. The gas produced from a can of fruit that 

 is working, the odor of meat that is decaying, the mold on bread or meat 

 or fruit, the rot and mold on eggs, all are typical results of the activity 

 of micro-organisms and are indeed well known to the housekeeper. Bac- 

 teria, yeasts, and molds grow everywhere — on ground, in water, and in 

 air. They are very light and are easily blown about, alighting on the 

 surface of furniture, on our hands and faces, on our utensils, on unpro- 

 tected and exposed food. Like all other forms of life they are in search 

 of a living, and the clothes that we wear (as when mildewed), the foods 

 that we eat, and even our bodies (when diseased) may all become foods 

 for them. Sometimes we intentionally encourage their activity and pro- 

 vide a living for them, as when we add yeast to dough and for a while 

 coax the yeast into quick growth by giving it a warm corner to live in; 



