MAPLE SIRUP PRODUCERS MANUAL 



57 



HIGH PRESSURE 

 STEAM SUPPLY 



^ LARGE VAPOR VENTS ^ 



REMOVABLE 

 ^COVERS 



3 PARTITIONS 

 IN FINISHING PAN 



STEAM TRAP 



CONDENSATE RETURN 



FLOAT VALVE IN BOX 

 ON EACH UNIT 



DRAW -OFF VALVE 



■FILTER BOX 



FINISHED SIRUP 



Cha)i 11. — Multiple-unit steam evaporator. 



used to complete the evaporation. This combi- 

 nation has all the advantages of steam for 

 finishing the sirup, but requires a smaller, and 

 therefore less expensive, steam boiler. 



Va<'iiiiiii E\u|>«>rator 



Milk-concentration or fruit-juice evaporation 

 plants in maple-producing areas can be adapted 

 for evaporating maple sap. This was done dur- 

 ing the 1930's at Antigo, Wis., where a milk 

 plant was used to make sirup during part of the 

 day in the spring sirup season (3). 



The procedure used at Antigo is as follows: 

 The sap is concentrated to between 25° and 30° 

 Brix in the conventional open-pan evaporator 

 at the farm site. This is 90 percent of the 

 required evaporation. Evaporation is completed 

 in a vacuum evaporator at the central sirup- 

 finishing plant. This two-stage method of evap- 

 oration results in a nearly colorless and flavor- 

 less maple sirup. Such sirup is not marketed for 

 direct use, but it is ideal for the production of 

 high-flavored sirup, as described on page 106. 



A study at Cornell (42) showed that the use of 

 milk-plant equipment during off-jieak seasons 

 for evaporating maple sap was practicable but 

 that the sirup pi-oduced had to be treated by 

 the high-flavoring process to obtain marketable 

 maple sirup. The fixed costs for use of milk- 

 plant equipment are negligible. However, the 

 perishable, partly concentrated sap must be 

 transported to the milk-concentrating plant, 

 and use of a central sirup-finishing plant re- 

 quires a new procedure for maple-sirup produc- 

 tion. 



Siimiiiaiy 



(1) The steam evaporator provides a steady 

 source of heat, and danger of scorching is 

 minimized. The sirup produced is light col- 

 ored and delicately flavored. However, the 

 steam evajwrator is expensive to install. A 

 combination oil-and-steam system (two- 

 stage method of evaporation) is proving suc- 

 cessful; it has all the advantages of steam 

 but is less expensive to install. 



