276 ANNUAL REPORT OF THE Off. Uoc. 



cess. The closed top kettle is an iroo chest or retort into which 

 steam may be introduced under pressure, and thus raise the tempera- 

 ture of the boiling- water above the normal boiling point. After the 

 tilled cans are placed in this kettle, it is run full of water to the 

 upper blow-off pipe, and the lid is then bolted securely. As steam is 

 being introduced the upper blow-off pipe is left partially open until 

 the water boils or the thermometer registers 212° F. The blow-off 

 pipe is then closed tightly and the safety valve set to a temperature 

 of 240° F. The higher the degree of heat carried the shorter is the 

 time necessary for processing. 



The following list of products and the necessary temperature with 

 the required time in a closed-top process kettle is given by Duckwall 

 in '"BactGriology :" 



Corn, 250 degrees Fahrenheit, 55 minutes. 

 Young peas, 240 degrees Fahrenheit, 15 minutes. 

 Marrowfats, 240 degrees Fahrenheit, 25 minutes. 

 Milk, 250 degrees Fahrenheit, 50 minutes. 

 Products containing milk, 250 degrees Fahreoheit, 50 minutes. 

 Meats, 250 degrees Fahrenheit, 55 minutes. 

 Meat soups, 250 degrees FahrcDheit, 50 minutes. 

 Peaches, 240 degrees Fahrenheit, no time given. 

 Cherries, 240 degrees Fahrenheit, 2 minutes. 

 Plums, 240 degrees Fahrenheit, 2 minutes. 

 Pears, 240 degrees Fahrenheit, 12 minutes. 



Tomatoes, 240 degrees Fahrenheit, 10 minutes, hot; cold pack, 15 

 minutes. 



Apples, 240 degrees Fahrenheit, 2 minutes. 

 Berries, 240 degrees Fahrenheit, 2 minutes. 

 Lima beans, 240 degrees Fahrenheit, 25 minutes. 

 Pineapple, 240 degrees Fahrenheit, 8 minutes. 



Some of these products like corn, peas, beans and the meats can- 

 not be processed in open kettles, but the fruits and tomatoes may be. 

 The time required would be from three to six times as long. Perfect 

 sterilization means the killing of all bacteria that may have entered 

 the can before it was hermetically sealed. These bacteria, numerous 

 in variety, microscopical in dimensions and every where present, are 

 the organisms which cause all the "swells" and "spoilage" of packed 

 foods. Many of them are killed in a temperature of 212 degrees 

 Fahrenheit, but those which work mischief in corn and animal pro- 

 ducts escape death in a boiling temperature and therefore are sub- 

 jected to 250 degrees Fahrenheit to be overcome. Frequent 

 heavy losses due to imperfect sterilization have induced 

 some canners to use preservatives. This practice has met 

 with just criticism and it is certain that the pure food 



