122 



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



(2) By use of tanks of standard sizes cali- 

 brated in gallons for different depths of liquid. 

 The calibrations are usually made on a "dip 

 stick" calibrated for a specific tank size. The 

 stick is lowered vertically to the bottom of the 

 tank and the heipfht of the sap in the tank is 

 noted by the wet line on the stick. This line 

 indicates the depth and volurne of the sap. 

 Usually, when sap is delivered to the plant, it is 

 run into a receiving tank that can be calibrated 

 precisely. The calibrations should be accurate 

 to ± 1 gallon. 



(3) By its weight. The tank of sap is weighed 

 before and after emptying. The empty (tare) 

 weight is subtracted from the weight of the 

 tank and sap to obtain the weight of sap. The 

 weight of sap is divided by 8.39 (the weight of 1 

 gallon of sap). 



The only tangible constituent of sap that can 

 be used to establish its price is its solids con- 

 tent, which is measured and expressed as 

 ° Brix. This measurement is made at the plant 

 by using a quart sample taken when the sap 

 was picked up at the farm or when it was 

 delivered to the central plant (fig. 131). The 

 sample identified with supplier's name and date 

 can be stored a few hours before determining 

 its Brix value. Or its Brix value can be deter- 

 mined at the time the sap is picked up or 

 delivered provided its temperature is also deter- 

 mined at that time. 



The observed Brix value of the sap is the 

 value read to the nearest 0.1° from the test 

 instrument (hydrometer or refractometer); this 

 value, together with the measured temperature 

 of the sap, is recorded. From these, the true 

 Brix value of the sap is calculated. 



Corrections to be applied to the observed Brix 

 value to obtain the true Brix value of saps of 

 various temperatures are as follows: 



Temperature of sap, ° F. 



32-42 



43-53 



54-62 



63-66 



Correction to subtract from 

 observed Brix value 



CBrix) 



0.4 



.3 



.2 



.1 



The value of sap is not constant but varies 

 with its solids content (percentage of sugar), or 

 Brix value. The higher the Brix value, the 

 smaller the amount of sap required to produce 



1 gallon of sirup. Less water has to be evapo- 

 rated, less volume is handled, and less storage 

 space is required. Sap with the highest Brix 

 reading therefore has the highest value. 



The base price for sap is usually for sap of 2" 

 Brix. This base price is determined by a num- 

 ber of factors, the most important of which is 

 the price of the finished sirup. For sirup selling 

 at $9 to $12 a gallon, one New York producer 

 reported in the National Maple Syi-up Digest (1) 

 the following prices paid for sap delivered at 

 the evaporator plant in 1974. The prices can be 

 adjusted up or down by such factors as effi- 

 ciency of the plant, hours of operation, and 

 wage scales. 



True Brix value of sap ' 



1.5° 

 1.6° 

 1.7° 

 1.8° 

 1.9° 

 2.0° 

 2.1° 

 2.2° 

 2.3° 

 2.4° 

 2.5° 

 2.6° 

 2.7° 

 2.8° 

 2.9° 

 3.0° 

 3.1° 

 3.2° 

 3.3° 

 3.4° 

 3.5° 

 3.6° 



3.r 



3.8° 

 3.9° 



4.0° 



Price per gallon 

 (cents) 



2.9 



3.9 



4.9 



5.8 



6.6 



7.3 



7.9 



8.5 



9.1 



9.7 



10.2 



10.7 



11.2 



11.7 



12.2 



12.7 



13.2 



13.7 



14.2 



14.7 



15.2 



15.7 



16.2 



16.7 



17.2 



17.7 



' True Brix value is the observed Brix reading corrected 

 for temperature. 



Storing Sap 



The central evaporator plant must provide 

 facilities to store a full day's production of sap. 

 There is no precise means for estimating the 

 size. However, experience has shown that on 

 days when sap flows well, ft'om 4,000 to 20,000 

 gallons will be produced per 10,000 tapholes. 

 Thus, a plant having a capacity of 8,800 gallons 



