Chemical and Physical Papei's. 41 



ON THE COLORING MATTER IN FRUIT JUICES. 



(Abstract.) 



By E. H. S. Bailey and E. L. Tague, University of Kansas. Lawrence. 



rr HIS work was undertaken in order to find out, if possible, some 

 scheme for detecting the different natural colors of fruit juices, 

 and also the different artificial colors used .in the preparation of 

 food products. Experiments were made upon the juice of Red 

 raspberries, Black raspberries, huckleberries, strawberries, black- 

 berries, Red currants and Black cherries. 



This work was carried out along three lines: (1) To find new 

 solvents for natural colors; (2) to apply known tests to these ex- 

 tracts; and (3) to find new characteristic tests to be applied to col- 

 oring matters extracted by known methods. 



The solvent power of carbon tetrachloride, several hydrocarbons 

 and sulphonic acids were tried with negative results. It was found 

 that ethyl alcohol, propyl alcohol and isobutyl alcohol were good 

 solvents, if the fruit juice was first saturated with sodium chloride. 

 Cymene, quinoline and pyridine were found to be good solvents. 

 Cymene would extract the coloring matter from other extracts, e. g., 

 acetone, and leave the original clear and colorless. Pyridine gave 

 characteristic reactions with the fruit juices themselves. 



An effort was made to diazotize the different coloring matters, 

 with some encouraging results. The effects of oxidizing and re- 

 ducing agents were tried and the resulting colors were tested with 

 (1) acids, (2) bases, and (3) salts, and results tabulated. Several 

 oxidizing and reducing agents were tried, among which bromine 

 was found to be the best oxidizing agent and sodium hydrosulphite 

 the best reducing agent. The sbove scheme of oxidation and re- 

 duction, with subsequent treatment with acids, bases and salts, 

 gave splendid results. 



The work was extended so as to include some of the coal-tar 

 colors and also some of the harmless vegetable colors permitted to 

 be used in food products. The tables of the results show that 

 natural fruit juice colors can be readily distinguished from each 

 other and from the coal-tar dyes, as well as from the vegetable dyes, 

 in this manner. If coal-tar dyes are mixed with natural colors, as 

 would be the case in food products, they can be separated by the 

 double-dyeing method given in U. S. Bulletin No. 25. Since nat- 

 ural colors do not dye in the second bath, the above scheme can be 



