SUGAR-CANE SIRUP MANUFACTURE o1 
also on whether or not chemicals are used as clarifying agents. The 
use of chemicals as clarifying agents is practiced, for the most part, 
only by the larger manufacturers, who use steam for evaporation 
and may even be able to filter the juice or sirup at any stage. When 
sirup is made on a comparatively small scale, as is the most general 
practice through the sugar-cane belt, suitable regulation of tempera- 
ture and careful skimming are the requirements for producing good- 
quality sirup. 
BOILING AND SKIMMING METHOD 
By M. A. McCauip and C. F. Watton, Jr., Bureau of Chemistry, U. S. Depart- 
ment of Agriculiure 
When heat is applied to cane juice, certain proteins and other 
nonsugar substances become coagulated. Some of this coagulated 
material rises to the surface of the juice and some sinks to the bottom. 
By the most approved practice, this material is removed as quickly 
as possible by skimming when it appears at the surface of the juice, 
after being coagulated by heat. Success in making sirup depends 
first of all on the thoroughness with which the juice is skimmed be- 
fore it begins to boil rapidly. The agitation of the juice due to 
active boiling breaks the coaguiated material into smaller particles, 
which are more difficult to remove by skimming than the original 
mass. This breaking up of coagulated material is commonly re- 
ferred to by sirup makers as ‘“‘ boiling in”’ the impurities. Additional 
nonsugar substances separate as boiling continues and the juice be- 
comes denser, making it advisable to continue the skimming until 
the juice has been evaporated to the density of finished sirup, even 
when skimming has been most carefully done at the beginning of 
evaporation. 
KETTLES 
Of the many types of equipment used for concentrating juice to 
sirup, kettles are probably the oldest. Less skill is required to make 
sirup with kettles than with any other means of evaporation, and a 
product of good quality results when they are properly operated. 
The advantages in using kettles for small-scale sirup making are: 
(1) The density of the finished sirup may be readily controlled; (2) 
the method is easy to operate; (3) a long period of time is available 
for skimming, thus making it possible to obtain a clean sirup; (4) 
long-continued boiling causes increased inversion, giving a sirup with 
a diminished tendency to crystallize. The disadvantages are: (1) 
A long period is required for evaporation, frequently 314 hours to-a 
batch; (2) a dark product is obtained as a result of the prolonged slow 
boiling; and (8) it is feasible only on a very small scale. 
©) 
EVAPORATORS 
Most of the sugar-cane sirup made by farmers operating on a com- 
paratively small scale is made on open galvanized-iron or copper 
| evaporators. A galvanized-iron evaporator is cheaper than one of 
| copper and, while new, will produce sirup of as good quality as can 
be made in the copper evaporator. A galvanized-iron evaporator 
also will last a reasonable length of time. Cane juice, however, is 
BC 
