64 



MAPLE-SAP SIRUP. 



Invert sugar content of maple sirups. 



The fact that over half of the sirups contained less than 1 per 

 cent and only one-tenth of them had over 3 per cent of invert sugar, 

 one having none, suggests that large quantities of reducing sugars 

 are abnormal and indicate carelessness in manufacture. Their 

 presence comes from inversion of the sucrose during either the souring 

 or concentration of the sap or results from the fermentation of the 

 finished sirup. Published analyses of sap have in only a few cases 

 shown reducing substances present, but it is doubtful whether the 

 samples examined were fresh and perfectly sweet and whether 

 allowance was made for the reducing action of the sucrose. If the 

 21 fermented samples containing over 5 per cent of invert sugar are 

 disregarded an average figure of 1.2 per cent of invert sugar is obtained. 

 Holding these samples in cold storage through the summer did not 

 increase the percentage of invert sugar when the sirup was boiled 

 down to a water content of 34 per cent and lower. 



As to the composition of the reducing sugars it is seen from the aver- 

 age analysis of the United States samples that there is present about 

 1.49 per cent and the difference between the Clerget sucrose and that 

 determined by the direct polarization is 1.71 per cent. The average 

 of all samples shows 1.47 per cent of invert sugar present and a differ- 

 ence between the two sucrose determinations of 1.93 per cent. In 

 these cases, then, 1 per cent of reducing sugars neutralizes 1.14 and 

 1.31 per cent of sucrose at 20 C., respectively. Since 1 per cent 

 of invert sugar at 20 C. neutralizes 0.301 per cent of sucrose, while 1 

 per cent of levulose in a 2 per cent levulose solution neutralizes 1.38 

 per cent of sucrose, this would seem to indicate that the reducing 

 sugars present are nearly all levulose. If the percentage of reducing 

 sugar is high, however, these facts are not so noticeable as when it is 

 low, as is shown in the following table. The lower the reducing 

 sugar content (as invert), apparently the higher the 1 per cent sucrose 

 equivalent. This would seem to indicate that there is a levorotatory 



