PRESERVATION OF FOOD. 



HOME CANNING. 



HAT is canning? Canning is the method of preservation 

 based upon a simple plan of keeping bacteria away from 

 food products, and has been devised in the last century. 

 This has come more and more into common use, until 

 to-day it is employed to an almost incredible extent. The method 

 spoken of is canning. The food is not treated by any antiseptic for 

 the prevention of bacterial growth, but reliance is placed simply upon 

 devices for keeping all bacteria from it. If this can be done, the food 

 will not be subject to their action and will never spoil. 



Bacteria are almost universally distributed in earth, air, and water. 

 This fact makes it extremely difficult to protect food from their action, 

 and without special devices it is quite impossible to do so. All food 

 material meats, fruits, or vegetables is sure to contain bacteria 

 when it reaches the home or the canning-factory. From some source, 

 either air, water, or earth, every kind of food material is sure to become 

 contaminated. We must recognize, then, that bacteria will be found 

 with absolute certainty in every kind of fresh food. Hence the process 

 of keeping food by protecting it from bacteria must consist of two 

 steps : ( i ) Some means must be devised for removing the bacteria 

 already present in the food; (2) the access of all other bacteria must 

 be absolutely prevented. If these two objects can be accomplished, the 

 food will be protected from bacterial action and thus protected may be 

 preserved indefinitely. No limit has ever been found, and we have no 

 reason for questioning that it might be preserved for centuries without 

 any subsequent change, provided it could be kept absolutely free from 

 the attack of micro-organisms. This method therefore offers almost 

 unlimited possibilities in the way of preserving food for future use. 

 It demands care in its application, but the results when properly 

 obtained are permanent. 



Success in canning necessitates the destruction of these organisms. 

 A temperature of 160 to 190 Fahr. will kill yeasts and moulds. 

 Bacteria are destroyed at a temperature of 112 Fahr. held for the 

 proper length of time. The destruction of these organisms by heat 

 is called sterilization. 



METHODS OF CANNING. 



There are four principal methods of home canning. These are : 



(i.) Single-period or Cold-pack Method. 



