FEUITS AND FKUIT JUICES. 47 



Table 12 includes the analyses made in this laboratory of both fruits 

 and juices. In the preparation of these samples the edible portion of 

 the fruit was finely ground by passing through a food chopper, and a 

 portion of this was saved for the analysis of the whole fruit. The other 

 portion was placed in a jell\^ bag and the juice removed b}^ pressure. 

 Unless the juice came through clear it was filtered or allowed to stand 

 and then decanted. 



The table is so arranged as to best permit of comparison between 

 the analyses of the fruits and the juices. The following points are of 

 interest regarding the analytical results : 



Solids. — The percentage of insoluble solids varies widely with dif- 

 ferent fruits, the lowest being !>.(I4 per cent in case of the cherr}^, and 

 the highest 11.23 per cent in one of the samples of black raspberries. 

 The insoluble material consists principally of fiber, although it also 

 contains a small amount of ash and considerable nitrogenous material. 

 The percentage of soluble solids in the whole fruit is usuall}^ consid- 

 erably lower than the percentage of total solids in the corresponding 

 juice on account of the concentration brought about in the separation 

 of the juice. 



Ash. — The content of ash also varies widely with the various fruits, 

 but is fairly constant in the difierent samples of the same fruit. Inva- 

 riabh^ the whole fruits have a content of ash appreciably higher than 

 the corresponding juices,- indicating that a portion of the ash remains 

 in the insoluble material, probably in the form of calcium salts. The 

 composition of the ash of pure fruits and fruit juices is in some 

 respects characteristic. As will be seen from the table, it consists 

 largely of carbonates (sodium, potassium, calcium, and magnesium 

 carbonates), while sulphates and chlorids are seldom present in appre- 

 ciable amounts. With the amount of material taken for the determi- 

 nation of ash there is seldom more than a trace of either sulphates or 

 chlorids. The alkalinity of the ash of pure fruit products is also char- 

 acteristic, and this feature may be taken as an indication of the purity 

 of the goods. Calculated as potassium carbonate, the average alkalin- 

 ity of the ash of the fruits is 77 per cent of the total ash and of the 

 juices 84.3 per cent of the total ash. 



Acidity. — No attempt was made to separate and determine quantita- 

 tively the various organic acids, although it is well known that the 

 acidity of the greater number of fruits is due not to a single organic 

 acid, but to mixtures of organic acids and acid salts. The total acid- 

 ity, therefore, was determined and results expressed as sulphuric acid 

 (H2SOJ. The acidity is exceedingly variable with different fruits, and 

 even with different varieties of the same fruit. 



Protein. — The nitrogenous material of the fruit is largelv in an 

 insoluble form. In the one sample of cherries examined the protein in 

 the whole fruit was not greatly in excess of that in the juice, while in 



