Processing 243 



ordinary forms of ferment organisms are killed at the boil- 

 ing point of water. But the spores or resting stage of 

 these organisms will not be killed at that temperature, so 

 that it is necessary to do one or all of three things: in- 

 crease the length of time of the cooking process, increase 

 the boiling point by increasing the steam pressure, or by 

 repeated cooking and cooling. In the ordinary process of 

 boiling some kinds of organisms may not be killed by be- 

 ing subjected to that temperature for just a few minutes, 

 whereas if the temperature is maintained for some time 

 they are killed. 



Boiling Repeatedly 



By boiling, all of the living organisms will be killed and 

 then by allowing the product to cool, any of the spores 

 which remain will germinate, so that a second boiling in 

 the course of twenty-four hours will kill the second crop 

 and leave the contents in practically a sterile condition, al- 

 though a third boiling may be necessary to make absolutely 

 certain. Repeated boilings in this manner are hardly nec- 

 essary with the usual forms of garden produce when the 

 boiling point of water is nearly 212 degrees. But when 

 the boiling point falls as low as 205 degrees or less, as it 

 does at high altitudes, then the repeated boiling is neces- 

 sary unless the cooking can be done in a steam tight vessel 

 where the steam pressure can be increased, or else by 

 keeping the produce at the boiling point a number of hours. 



Processing 



This cooking through which the produce must go in 

 order to make it keep is known among canners as "pro- 

 cessing," although its only meaning is thorough cooking 

 in order to destroy all germs of fermentation and decay. 



This work can be very effectually done in open kettles 

 in the home pr small factory, although for rapid work and 

 in large establishments it is an advantage for some kinds 

 of produce to have steam tight compartments in which the 

 sterilization can be done at a temperature higher than the 

 boiling point of water in an open vessel. 



