JAMS. 59 



handed reading of the dextrin. The presence of preservatives inter- 

 feres to a considerable extent and in some cases prevents complete 

 fermentation. As a result left-handed readings were obtained which 

 showed that considerable of the levulose was still unfermented. It is 

 always well to test for reducing sugars even if a zero reading has been 

 obtained for the reason mentioned above. 



The percentage of nitrogenous material in the jams is quite vari- 

 able much more so than in the jellies on account of the pulp present 

 in the former, which contains a large part of the nitrogenized bodies 

 in an insoluble condition, as can be seen by comparing the protein of 

 juices and whole fruits in Tables 14 and 15. The percentage of pro- 

 tein in jam, therefore, will depend largely upon the amount of fruit 

 pulp used and is thus an indication of the amount of fruit employed, 

 which in some of the jams is evidently rather small. The protein con- 

 tained in compound jams and jellies (see Tables 26 and 33) is nearly the 

 same, which is quite different from the condition found in the fruit jams 

 and jellies which contained no glucose. The other constituents of the 

 compound goods also vary little, showing that there is little difference 

 in the process of making them or the ingredients used. 



The high protein content of sample 20175 perhaps needs some expla- 

 nation. The currants used in the preparation of this jam were hard 

 and tough and looked as though they had been dried before being 

 used in the preparation of the jam. As a result the insoluble matter 

 is very high (6.32 per cent), as are also the proteids (1.410 per cent), 

 the ash (0.841 per cent), and the acid (1.117 per cent). 



There is little that can be said about the acid content except that 

 certain fruits, such as currants and plums, have a high content of acid 

 as a rule, and jellies and jams made from them should also have a high 

 acidity. For this reason the acid content may sometimes be of value 

 as evidence that there has been some substitution of other fruits for 

 those mentioned. 



Jams containing no glucose. Of the 18 commercial samples in the 

 table, about one-third contained preservatives and 3 were artificially 

 colored with coal-tar dyes. 



TABLE 21.-- Description of jams not cotitaining glucose. 



