The Preservation of Food in the Home. — Part I 1267 



experimenting, the manufacturers have worked out the best tem- 

 peratures and lengths of time for the cooking of foods put on the 

 market. There are a few mechanical devices to be piir chased for use in 

 the household, which will enable the housekeeper to obtain the high tem- 

 perature required for this quicker method of food canning, but they are 

 expensive and require more care to insure good results than does the 

 ordinary use of the steamer, hot-water bath, or open kettle. 



A piece of apparatus called the autoclave has come into use in some 

 households where an effort is made to realize a profit on the fruit by selling 

 food canned in glass jars. The autoclave is a utensil in which steam is 

 under pressure and by which a temperature higher than that of boiling 

 water may be obtained. It requires careful handling to obtain correct 

 temperatures and to prevent serious accidents from high steam pressure 

 with the attendant danger of the blowing up of the apparatus. A rela- 

 tively inexpensive autoclave may be purchased, which has a capacity of 

 about four hundred two-pound cans. As the high-temperature cooking 

 for certain vegetables does away with the necessity of intermittent cook- 

 ing, the use of the autoclave is, under some circumstances, an economy. 



While the process of sterilization by heating foods intermittently for 

 several days may be used for all foods, it is not necessary to take so much 

 trouble with all. Fruits and tomatoes are much easier to sterilize than are 

 the general run of vegetables, because they contain acids; hot acid, even 

 if dilute, aids materially in destroying micro-organisms, both in the spore 

 and the vegetable stage, during the cooking process. One day's cooking 

 for a moderate time is therefore usually sufficient for acid-contairnng foods. 



Details of canning. — Good results in canning are more nearly certain if 

 environment, food, and receptacles are clean; the danger of reinfecting 

 carefully sterilized material with destructive organisms is then lessened. 

 It must not be assumed that hands, dishcloths, and such utensils as have 

 not been boiled or have not come in direct contact with a flame are clean 

 in the sense of the cleanliness needed in canning foods. The grit and 

 sand that are left on fruits and vegetables and that we ordinarily regard as 

 dirt will not interfere with the keeping of canned foods; but the invisible 

 dirt in the form of micro-organisms which is found on even well-washed 

 hands, dishcloths, towels, and any other article likely to be used in the 

 work, may interfere seriously with good results. If, therefore, food and 

 containers have been thoroughly freed from destructive micro-organisms 

 by the action of heat, they must not be reinfected by coming in contact 

 with hands that have not been so treated. A careful housewife, following 

 directions, boiled the jars that were to contain her canned tomatoes. Then, 

 because the water was hard and lime was deposited in the jars, she as 

 carefully used a dish-towel to wipe them out. One may imagine what' 

 probably resulted. 



