COMMEECIAL CANNING OF FOODS. 13 



with others the volume of solids and its own liquid is a fairer measure. The buyer 

 is entitled to a full can and most packers try to furnish it. The net weights given for 

 several products at the close of the descriptions of processing are intended to represent 

 the minimum; the amount actually obtained should exceed these figures. A lower 

 net weight may be regarded as "slack filled. " 



USE OF THE TERM "CANNED." 



The term "canned" as applied to food products put up in hermetically 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 commercially 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 tins, 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 commercial 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 fruit in 

 glass. 



SPOILAGE. 



Spoilage may result from insufiicient processing, defective containers, 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, owing 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 de\'ice3, 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 sfjurs 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 condition frequently exists under 

 the conditions just cited. Swells are therefore more likely to be associated with rush 

 operations and flat sours with an overstock or delay in getting at the raw material. It 

 ia not Intended to give the iinpression that swells and sours may not occur under other 

 conditions, such as changes in the consistency of the corn, nor that swells may not 

 o<jcur in material which has stood, and sours result from underprocessing, but only 

 ttj state a general rule. 



Swelling or Houring may take place shortly after processing or the spoilage may be 

 delayed for weeks or even months. Swelling is more likely to occur and be detected 

 early, while souring is apt to be delayed, though it may occur early. The heat used in 



