SUGAR-CANE SIRUP MANUFACTURE 81 
semisirup sediments much more rapidly than that in final sirup; in 
fact, some of the suspended material that can be removed from the 
low-density sirup by sedimentation will not settle out from the final 
sirup within a reasonable length of time. 
If the juice is evaporated in multiple-effect evaporators, the same 
density should be reached in the first stage of the procedure as in the 
case of juice evaporated in open pans, and the semisirup likewise 
should be subjected to brushing and settline. Sirup concentrated in 
vacuum is deficient in typical aroma and flavor and should be finished 
in aN open pan; open evaporation imparts a distinctive flavor. I 
the sirup is to be concentrated to final density under vacuum, this 
should be accomplished in a pan at low vacuum. The process of 
evaporation should be conducted as rapidly as possible, regardless of 
the type of pan used. Sirup heated for a long time, especially in an 
open pan, is very likely to be dark. Rapid evaporation in an open 
pan may be obtained by keeping the layer of juice relatively thin. 
Speed in a multiple-effect evaporator 1s obtained by keeping the 
apparatus in good order and the heating surface free from scale. In 
both cases a plentiful supply of steam should be available. 
CONTROLLING THE DENSITY 
The density to which sirup is evaporated in this process may be 
controlled by the use of a Baumé or a Brix hydrometer. <A small 
sample of sirup from the boiling mass is caught in an upright tin or 
copper cylinder and the spindle is floated init. Sirup testing 35° to 
35.5° Baumé (63.9° to 64.9° Brix) at 185° F. will, when cooled to 
ordinary atmospheric temperature, test 38.5° to 39° Baumé (70.8° to 
71.8° Brix), which is the eae ordinarily preferred by the market. 
The same sirup will test 34° to 34.5° Baumé (62° to 63° Brix) at 200° 
to 210° F. Gmmediately after removal from the evaporator). The 
Brix hydrometer is similar to the Baumé hydrometer in appearance 
and use (p. 16), but the scale is so designed that the readings represent 
the approximate percentage of dissolved solids in the juice or sirup. 
Table 10 shows the manner in which variation in temperature affects 
the Baumé and Brix readings of a given sirup. Thus, if a sirup tests 
34.7° Baumé (63.3° Brix) at 210° F., it will test 39.5° Baumé (72.8° 
erix) at .72°,K, | 
TABLE 10.—Observed densities of sirup at different temperatures , 
nes Temperature oe Temperature 
° Baumé| ° Briz CuG: OOH ° Baumé| ° Brix EGE ©! 78 
34. 7 63.3 98. 9 210 Silene 69. 49.0 120 
Bay 5 64. 5 85. 0 185 38.3 70. 4 41.0 106 
36. 1 66. 0 | 80. 0 176 38.9 Tals) 35. 0 95 
36.6 67.0 70.0 158 39.1 72.0 29.0 84 
Olen 68. 0 60. 0 140 39.5 72.8 22.2 72 
37.4 68.5 55.0 131 | 
The Baumé or Brix reading for any given sample of juice or sirup 
varies with the temperature at which the reading is made. Most of 
the Baumé hydrometers used in the sirup industry are graduated at 
the standard temperature of 17.5° C. (63.5° F.), although some hy- 
drometers graduated at 20° C. (68° F.) are in use. To use the 
hydrometer accurately, therefore, it is necessary either to cool the 
sirup to the standard temperature or to consult an appropriate table 
for the temperature correction. Since the sample is customarily 
