56 MAPLE-SAP SIRUP. 



In other instances these substances were added to the thickening 

 sirup without stopping the process. The two methods seem to yield 

 the same results. The addition of this material brings the scum to the 

 surface, where it is skimmed off constantly. It is claimed by many 

 makers that this procedure is necessary if a fancy sirup is to be made, 

 but a larger percentage of the clear sirup samples came from those 

 using neither milk nor eggs. The use of these materials is a tradition 

 among some makers, and few have ever tried to produce a clear sirup 

 by any other means. It is also claimed that the color of the 

 product is lightened by their use, a point which was hardly substan- 

 tiated by the data collected (see p. 95). 



A few makers use baking soda and saleratus in boiling the sap. 

 This tends to neutralize the acidity of the juice, but has no cleansing 

 effect. When boiling fermented or sour sap its use is beneficial in 

 neutralizing the acidity, and thereby preventing further inversion of 

 the sucrose. Its excessive use, however, is likely to change the color 

 of the sirup, as any alkaline sugar juice when boiled turns dark. The 

 popular application of the term "sour sap" is to one differing in 

 appearance from the normal; it does not necessarily mean a sap with 

 an increased acidity. One hears of milky sap, stringy sap, red sap, 

 and at the end of the season green sap and yellow sap. Edson a has 

 shown that the acidity of these changed saps is not much greater than 

 that of the normal. His work on the bacterial flora of the sap has 

 shown that the different forms of sour sap are due to different bacteria, 

 and these do not increase the acidity materially. Under such condi- 

 tions, the addition of the soda would hardly be more necessary than 

 with a normal sap. However, there are forms of souring that do pro- 

 duce an increase of acidity, and in such cases soda would improve the 

 product by preventing further inversion of the sucrose. Again some 

 run a piece of fat meat over the surface to keep down the excessive 

 frothing or place a little lard in the boiling pan or kettle. These prac- 

 tices may have to be resorted to occasionally, but they are not gener- 

 ally advisable, as the flavor is greatly changed if the application has 

 been made often. In general, the use of any chemical substance as a 

 cleanser is superfluous and expensive. 



a Vermont Agricultural Experiment Station Bui. 151. 



