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AGRICULTURE HANDBOOK 134, U.S. DEPT. OF AGRICULTURE 



Table 13. — Viscosity of sucrose solutions of various densities (° Brix) at temperatures of 20° C. (68° 



F.)tol05° C. {221° F.y 



' Based on data from Circular C440 issued by the National Bureau of Standards, U.S. Department of Commerce, July 

 31. 1958. 



' Values obtained by extrapolation. 



sugar. It would not meet specifications for 

 standard-density sirup, would tend to spoil eas- 

 ily, and would have a low viscosity and there- 

 fore would taste watery. 



Therefore, with a good indicator to detect the 

 end point of evaporation (thermometer cali- 

 brated in V4° F.), together with the slowdown in 

 rate of evaporation, as shown in chart 16, the 

 sirupmaker is able to stop evaporation precisely 

 at the desired concentration. He can do this 

 either by drawing off the sirup from the evapo- 

 rator or, if he uses a finishing pan, by turning 

 off the heat. 



Finishing Pan 



When a finishing pan is used, it is necessary 

 to know when the sap has been concentrated 

 enough to be transferred from the evaporator 

 to the finishing pan. This can be determined by 

 measuring the elevation of the boiling point of 

 the partly concentrated sap. Table 12 shows the 

 elevation of the boiling temperature of sugar 

 solutions (above that for water) for concentra- 

 tions from 0° to 73.5° Brix. 



To use the table, determine the boiling tem- 

 perature of pure water and then observe the 



boiling temperature of the partly evaporated 

 sap. The difference between the two boiling 

 points represents the elevation in boiling tem- 

 perature. 



Two examples of how to select a boiling point 

 elevation to give sirup of a desired density 

 (° Brix) follow: 



Example 1. A producer wants to draw off 

 sirup from the evaporator at about 40° Brix. At 

 what boiling temperature should the sirup be 

 removed if water boils at 210° F.? 



Table 12 shows that the boiling temperature 

 is elevated 2.0° F. for solutions having a density 

 of 40.5° Brix. Thus, when the boiling tempera- 

 ture rises to 212° F. (210° + 2°), the sap will be 

 concentrated to approximately 40° Brix. 



Example 2. A producer wants to concentrate 

 the sap to 50° Brix in the evaporator before 

 transferring it to the finishing pan. At what 

 boiling temperature should the sirup be drawn 

 off if water boils at 211.5° F.? 



Table 12 shows that for solutions having a 

 density of 50.4° Brix, the boiling temperature is 

 3.2° F. above the boiling point of water. Thus, 

 211.5° + 3.2°, or 214.7°, is the boiling tempera- 

 ture of 50° Brix sirup. 



