STERILIZATION FOR CANNING IQt 



forms of life, and hence the simple heating of food will 

 destroy all bacteria. The material to be canned must be 

 cut up into pieces of convenient size, which will depend 

 somewhat upon the kind of material. In general, the 

 larger the pieces the more attractive the appearance of 

 the product when finished, but the greater the difficulty 

 of canning. Cherries, plums, and berries can be left whole ; 

 pears are cut into halves or quarters ; while apples are 

 commonly cut into smaller pieces. These pieces are to be 

 placed in water and heated. The process of canning is 

 therefore applicable only to materials that are not greatly 

 injured by immersion in water and subsequent boiling. 

 Hence it is useful for foods which cannot be well preserved 

 by drying. 



In the application of heat several points, must be borne 

 in mind, i . It must be remembered that the destruction of 

 the organisms capable of growing in the particular food to 

 be canned must be absolute. If a single individual micro- 

 organism is left alive in the food after the boiling, and finds 

 conditions favorable to its growth, the whole process is use- 

 less and the canning will be a total failure. One live bac- 

 terium, capable of growing and multiplying, can produce 

 a subsequent putrefaction and destruction of the food with 

 just as great certainty, though not so quickly, as if a million 

 of them were left alive. Therefore, unless the food contains 

 substances which inhibit bacterial growth, the preliminary 

 heating must be a complete sterilization, that is, a heating 

 so thorough that every individual bacterium is destroyed. 

 No halfway processes are of any use whatsoever ; it must 

 be total and absolute. This is by no means easy, and most 

 failures in canning are due to the inability to bring about 



