New York AGRICULTURAL EXPERIMENT STATION. 49 
been strong incentives for improving methods. ‘“ Soured” cans 
give no external evidence of being abnormal; but when opened 
the contents emit a sour smell and have an acid flavor. With 
peas, the odor is not disagreeable, the liquor is milky and the 
flavor ranges from faint to decidedly acid. Where the acid is 
formed after the cans are heated, especially if the goods are 
held some time at 70° F. or above, enough gas is formed to 
cause the ends to bulge slightly. In such cases the cans are 
commonly classed as “swells.” However, in case the acid is 
produced before the cans are heated or where the cans have been 
held at low temperature no change is apparent until the cans are 
opened by the consumer. As long as the public was not edu- 
cated to expect fine quality, a considerable amount of sour goods 
was undoubtedly consumed without question. Now the con- 
Sumers have become more discriminating and the increased pro- 
test against sour goods is one of the results. 
CAUSE OF THESE LOSSES. 
The fact that fermentations in general are so commonly caused 
by the lower forms of plant life leads to the widespread belief 
that all the difficulty in keeping canned goods can be attributed 
to the same cause. While it is probably true that a large pro- 
portion of the swelling and souring is due to the growth of 
bacteria within the cans undoubtedly exceptions will be found. 
It is also true that there are a number of different species of 
bacteria which produce swelling or souring of the same i Nps 
in different factories. 
FACTORS WHICH ASSIST IN KEEPING CANNED GOODS. 
There are several factors which combine to make commercial 
canning possible. Fresh and clean fruits and vegetables are 
desirable because they carry smaller numbers of the germs which 
it will be necessary to destroy. This means cleanliness in the 
utensils and persons with which the materials come in contact 
before entering the cans. Pure air is desirable, especially for the 
workmen, but its effect on the product has often been over-esti- 
mated. 
Where large quantities of sugar are used with fruits the sugar 
tends to restrain the growth of germs which may be present. 
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