MAPLE SIRUP PRODUCERS MANUAL 



107 



Unfortunately, high temperatures favor the 

 formation of an acrid "caramel" flavor. The 

 presence of large amounts of water favor cara- 

 mel formation and the presence of some cara- 

 mel in the initial sirup accelerates it (90). There- 

 fore, only the two top grades of sirup — U.S. 

 Grade AA (Fancy) or U.S. Grade A (No. 1)— 

 should be used in making high-flavored maple 

 sirup. It may be made by the atmospheric 

 process (H9), by the constant-volume pressure- 

 cooking process (139)? or by the new continuous 

 process. 



High-flavored maple sirup made from U.S. 

 Grade AA or U.S. Grade A sirup by either 

 process will have a strong full-bodied flavor 

 four to five times that of the sirup from which it 

 was made, and it will be essentially free from 

 caramel. 



The high-flavored process does not concen- 

 trate the flavor; instead, it develops more ma- 

 ple flavor than present in the original sirup. 



Atmospheric Process 



In the atmospheric process the sirup is con- 

 centrated at atmospheric pressure by heating 

 to a boiling temperature of 25(y to 255° F. This 

 reduces the water content of the sirup to ap- 

 proximately 10 percent. The sirup is held at this 

 temperature for IV2 to 2 hours. It is then cooled, 

 and water is added to replace that lost in 

 evaporation so that the sirup is again of stand- 

 ard density. 



Because of the low moisture content of the 

 sirup during the cooking period, there is danger 

 of scorching if it is heated in a kettle on a stove 

 or other hot surface. It is recommended, there- 

 fore, that the high-flavoring process be con- 

 ducted with high-pressure steam in a steam- 

 jacketed kettle or in a kettle provided with a 

 steam coil (chart 22). 



The first step of the process — removing the 

 water from the sirup — should be done as rai> 

 idly as possible. Steam pressure of from 30 to 

 1(K) pounds should be used. As soon as the sirup 

 reaches a temperature of 252" F., the steam 

 pressure is reduced until only enough heat is 

 applied to maintain the sirup between 25(P and 



TRAP 



DRAIN 



STEAM OR WATER 

 CONNECTION 



" Described in U.S. Patent 2,054,873 issued to George S. 

 Whitby on September 22, 1936. This patent has expired, 

 and the process is now available for free use by the 

 public. 



Chart 22. — Kettle with steam coil can be built in any tin 

 shop. It is not as convenient to use as a tilting-jacketed 

 kettle, but very satisfactory results can be had with it. 

 Like the steam-jacketed kettle it must be operated with 

 high-pressure steam and the condensed water must not 

 be allowed to collect in the coils. Provision should be 

 made for running cold water through the coils for 

 cooling the sirup. 



255°. Usually a steam pressure of 20 to 28 

 pounds is sufficient. A cover is placed over the 

 kettle to prevent further loss of water through 

 evaporation. The cover need not be airtight. 

 Because of the high viscosity of the sirup, little 

 water will be vaporized. 



A thermometer calibrated in 1° intervals, 

 with a range that includes 250^ to .30(f F., is 

 kept in the sirup during the high-flavoring 

 process. If the temperature of the sirup rises 

 above 255° during the holding period, the steam 

 pressure should be decreased. To prevent for- 

 mation of crystals, the sirup should not be 

 stirred or agitated during the high-flavoring 

 process. 



The end of the heating (cooking) period is 

 best determined by odor. The cover is lifted, and 

 a handful of steam is scooj^ed up and brought 

 toward the nose; heating is stopped as soon as 

 an acrid caramel odor is detected in the steam. 

 Care must be taken not to get a steam burn. 



