28 THE CANNING OF FOODS. 



USE OF THE TERM " CANNED." 



The term " canned " as applied to food products put up in her- 

 metically sealed packages is capable of more than one meaning. 

 Originally it meant any food put up in any container which might 

 be hermetically sealed and the preservation accomplished through 

 sterilization by heat. In commercial use the term " canned " applies 

 only to foods put up in tin containers and sterilized by heat. Under 

 that construction any foods put up in glass or other containers than 

 tin are not rated as canned foods, nor are foods put up in tin in 

 which preservation is accomplished by some means other than heat. 

 Fish cured in brine, pickled, or spiced, but packed in tin, is not canned 

 within this meaning of the term. Fruits preserved with sugar, placed 

 in glass or tin jars, and sealed in vacuum are not canned in the com- 

 mercial sense. The same is true of smoked meats, such as dried beef, 

 and fish, as smoked herring. In domestic canning glass jars are 

 generally used, and the product is referred to in the home as canned. 

 It is unfortunate that the term should have so many meanings. In 

 the trade it is now common to refer to fruit in glass, sliced bacon 

 and chipped beef in glass or tins, sliced or smoked fish in glass or 

 sardines in tins, and candied fruits in glass. 



SPOILAGE. 



Spoilage may result from insufficient processing, defective con- 

 tainers, or the use of unfit material. These losses are generally 

 classed under the heads of swells, flat sours, and leaks. Formerly 

 losses were heavy at many factories, but these are becoming less each 

 year, due to a better knowledge of what is necessary in material, 

 handling, and improved appliances. More attention is paid to 

 testing for bacteria, and greater care is taken in obtaining accurate 

 thermometers and gauges, automatic temperature-regulating devices, 

 and time recorders, so that little is left to the judgment of the 

 processor or helper. 



Spoilage due to insufficient processing is generally divided into 

 two classes swells and flat sours. In the former there is generation 

 of gas, causing the ends of the can to become distended ; in the latter 

 the content of the can is sour, but there is nothing in the appearance 

 of the can to enable the customer to determine the condition until 

 the can is opened. Swells are generally due to underprocessing good 

 material, while flat sours most often result from giving the regular 

 process to material which has been allowed to stand for some time, 

 such as peas remaining in a load overnight or corn left in a car or 

 in a pile until it begins to heat. The raw material may show no 

 evidence of fermentation on superficial examination, but this condi- 

 tion frequently exists under the conditions just cited. Swells are 



