COMMERCIAL CANNING OF FOODS. 2h 
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 ascanned. Itis 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 insufficient 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 toa 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 isopened. 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 ina pile untilit 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 
is not intended to give the impression that swells and sours may not occur under other 
conditions, such as changes in the consistency of the corn, nor that swells may not 
occur in material which has stood, and sours result from underprocessing, but only 
to state a general rule. 
Swelling or souring 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 occurearly. The heat used in 
