124 



AGRICULTURE HANDBOOK 184, U.S. DEPT. OF AGRICULTURE 



However, the more common method is to move 

 sap from the receiving: tanks to the storage 

 tanks by i)iimi)s. 



Sap obtained from pijDelines is usually free of 

 foreign matter and does not need to be filtered. 

 However, sap obtained by other collecting 

 methods must be filtered to remove fine parti- 

 cles of bark and other foreign matter from the 

 sap. If not removed, this foreign matter may 

 serve as an unwanted source of color and cause 

 the production of dark, low-gi-ade sirup.- The 

 filter may be either a presscloth prefilter or 

 several thicknesses of muslin (fig. 133). 



It is desirable to use two or more sap-storage 

 tanks. This permits better control of sanitation, 

 plant operation, and production records. The 

 Brix value of the sap in each tank must be 

 determined since it may be a composite of sap 

 obtained from two or more sources that may be 

 of different sugar contents. If the volume of sap 

 in the tank and its Brix value are known, the 

 yield of finished sirup can be calculated (see p. 

 48). 



The evaporator house must be provided with 

 a gage to show the volume of sap in the storage 

 tank being used to supply sap to the evapora- 

 tor. Without a gage, the plant operator may 

 unexpectedly find the supply of sap exhausted, 

 and the evaporator pans may go diy and be 

 damaged by bm-ning. A simple type of gage can 

 be installed in the sap feed line from the tank to 



PN-1H29 



Figure 133. — Several layers of muslin or presscloth can be 

 used to filter sap. 



the evaporator This gage consists of a tee with 

 a long, upright, glass sight tube, the top of 

 which is open and above the level of the top of 

 the storage tank. The level of the sap in the 

 tube indicates its depth in the storage tank. 

 The tube can be calibrated in units such as full, 

 '/.,-full, etc., or in gallons. 



Handling und Storing Sirup 



Sirup tends to become darker each time it is 

 heated above 18(F F. Therefore, sirup should be 

 reheated as few times as possible. To insure a 

 sterile package, all sirup must be packaged at 

 temperatures above 19(F. It is advisable to 

 package the sirup immediately after it leaves 

 the filter or the finishing pan while it is still 

 above 190^. If the temperature of the sirup 

 drops below 19(]F before it can be packaged, a 

 small amount of heat furnished by a steam coil 

 with high-pressure steam, an electric immer- 

 sion heater, or a heat lamp will bring it back to 

 the desired 19(7 with a minimum of darkening. 



Sirup not immediately packaged can be put 

 in bulk storage. If it is stored in drums, they 

 must be completely filled with hot sirup 

 (19(F F.). Large tanks holding several hundred 

 or several thousand gallons can be used. Sirup 

 storage tanks, like sap storage tanks, should be 

 provided with germicidal lamps mounted to 

 illuminate the entire surface of the sirup when 

 the tank is filled. These lamps must be kept in 

 operation continuously from the time the tanks 

 are cleaned prior to filling until the last of the 

 stored sirup has been removed. If the sirup is 

 run into these tanks hot and sterile, there is 

 little chance that any microbial gi'owth will 

 occur below the sirup surface, and the germici- 

 dal lamps will keep the surface sterile. Sirup 

 stored in this way can be held indefinitely and 

 sirup can be added or withdrawn at any time. It 

 is not necessary to keep the tank cool. Tanks 

 with sterile lamps can be mounted outside, for 

 the ambient temperature has little or no effect 

 on keeping quality of the sirup. The sirup with- 

 drawn for packaging must be heated to sirup- 

 pasteurizing temperature (190" F.). 



The large storage tank also serves as a set- 

 tling tank. After several weeks of storage, the 

 sirup will be sparkling clear. 



