58 BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 
CANNING SIRUP 
OPERATION 
By W. L. OwENn, Louisiana Sugar Experiment Station 
PRINCIPLES CF CANNING 
Canning, as generally understood, is the act of filling cans with 
perishable goods and hermeticaliy sealing them. In a broader sense 
the process includes also the preliminary preparation of the prod- 
uct, by heat or other means, to insure it against subsequent deteriora- 
tion in the cans. in canning sirup the processing or conditioning 
of the sirup is implied, as well as the actual canning operation. The 
processing of cane sirup for canning is merely a partial sterilization 
to destroy the micrcorganisms which cause sirup to ferment. As 
the temperatures successfully used to preserve cane sirup do not 
kill microorganisms of all classes, the process is one of pasteuriza- 
tion rather than of sterilization. 
Cane sirup may be preserved in cans with little chance of failure, 
if certain simple rules are observed. There are no great difficulties 
to be overcome, and there is no reason why, even with the simplest 
equipment, cane sirup can not be canned with minimum loss from 
spoilage. The three general conditions necessary are (1) to fill the 
cans with sirup at the proper temperature, (2) to obtain air-tight 
closure of the cans, and (3) to avoid long retention of heat by the 
sirup both before and after canning. 
When the sirup has been concentrated to the desired density in an 
open pan, it should be cooled to the canning temperature as quickly 
as possible; otherwise, it will deteriorate in color and flavor. Owing 
to the tendency of cane sirup to retain heat for long periods, it is 
necessary, when handling large quantities in bulk while hot, to pro- 
vide means for hastening cooling. It is most economical, of course, 
to fill the cans with the sirup as rapidly as it cools to the proper 
temperature after bemg concentrated to final density in the evapor- 
ator. In this way the sirup does not need to be heated twice; a 
saving of fuel is effected; and the sirup does not suffer in flavor and 
color by being reheated. 
Sometimes sirup from a small open evaporator may be run into the 
sirup trough as rapidly as it is finished and canning may proceed 
at the same time. Again, depending on the size of the tank and the 
rate at which sirup is being made, two troughs or tanks may be better 
than one. Sirup may then be removed from one of these for canning, 
while hot sirup direct from the evaporator is being run into the second. 
Some sirup makers can the sirup directly as it comes from the evapor- 
ator, but this is not considered the best practice. The sirup should 
be cooled to at least 180° F. for gallon cans before canning is begun. 
When the temperature of the sirup in the tank has dropped to the 
safe minimum, 170° F. (p. 59), canning from that tank should be 
discontinued, and hot sirup from the evaporator should be run in to 
raise the temperature. 
The process of concentrating the sirup in large batches in an evap- 
orator sometimes proceeds much faster than the canning. In such 
cases means should be provided for cooling the sirup after concen- 
tration and for reheating or processing it in small batches at the rate 
required for canning. Special coolers may be provided whenever 
it is necessary to cool the sirup (p. 54). Ii the sirup is to be repro- 
