64. BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 
If the expense of installing an extra evaporator does not seem to | 
be warranted, a single evaporator may be used, discontinuing grind- |} 
ing while the semisirup is beg evaporated to finished sirup. The | 
sak additional equipment required is a tank for receiving the semi- | 
sirup. Hach sirup maker can easily determine from past experience | 
with continuous evaporators the best manner of operating the | 
evaporator in order to concentrate semisirup to final sirup. ' 
With an extra evaporator, preferably one of the noncontmuous | 
type, it is possible simultaneously to evaporate juice to semisirup | 
and to concentrate semisirup to final sirup. This increases the © 
capacity of the plant, justifyimg the expense of the second evaporator. | 
Since the concentration of juice is approximately two-thirds complete | 
at 20° Baumé, or 35.8° Brix (measured at the boiling temperature), 
the capacity of the finishing evaporator, should one be installed, need | 
be only about one-half that of the juice evaporator. Two tanks for | 
treating the semisirup with invertase are also essential in order that 
erinding may continue without interruption. | 
A plant in which approximately 10 tons of cane per 10-hour day | 
is to be ground needs two tanks holding about 500 galions each. | 
Ten tons of cane will yield about 1,500 gallons of juice, which will © 
make approximately 450 gallons of semisirup of the required density. © 
The installation of two tanks makes it possible to draw semisirup | 
from one for concentration to final sirup in the second evaporator, | 
while the first evaporator is evaporating mill juice to semisirup and | 
discharging it into the second tank. Thus a continuous operation 
may be maintained, one tank being filled with semisirup and one 
tank emptied each day. One evaporator would be in constant use, 
concentrating juice to semisirup, while the semisirup made the | 
previous day would be concentrated to final sirup in the other 
evaporator. The juice evaporator would be piped to discharge into | 
either tank, and each tank would be piped to discharge into the | 
semisirup evaporator. The use of invertase at 1925 prices would 
increase the cost of making sirup one-half to three-quarters of a 
cent per gallon of final sirup. One pound of the most active inver- 
tase preparation on the market is sufficient for 300 to 400 gallons of 
final sirup. 
SIRUP TO BE CANNED 
Although thestandard commercial density is about39° Baumé (71.8° | 
Brix), measured at ordinary temperature, it is believed that the sirup | 
density preferred by most consumers is about 35° Baumé (63.9° Brix), | 
measured at a temperature close to boiling, or approximately 40° | 
Baumé (73.7° Brix), when cooled to ordinary temperature. Sirupcon-_ 
centrated to higher density usually has somewhat poorer color and | 
flavor. The use of invertase during manufacture prevents crystal- | 
lization in canned sirup, even after the can is opened. The “‘apparent 
purity” (determined by use of a polariscope) should be approximately — 
50 to 55 for sirup evaporated to 40° Baumé, cold. Propercanning is | 
depended upon to prevent fermentation in sirup at this density. 
SIRUP TO BE BARRELED 
Several considerations govern the producer’s decision as to whether | 
or not to use invertase in barreled sirup which has a tendency to | 
crystallize. If the sirup has been contracted for in advance and the | 
buyer does not object to crystallization or is not willing to pay 
enough to justify invertase treatment, the use of invertase is generall 
