FLAVORING EXTRACTS. 71 



Test another portion of the filtrate from the resin for tannin with a solution of gel- 

 atin. Tannin is present in varying but small quantities. It should not be present 

 in great excess. 



6. DETERMINATION OF CANE SUGAR. 



See methods given on page 85. 



7. DETERMINATION OF ALCOHOL. 

 Proceed as directed on page 82. 



8. TESTS FOR COLORING MATTER CARAMEL. 



Of the artificial colors used in vanilla extracts, the most common is caramel. 



PreltntitKirt/ test. If on shaking the bottle of vanilla the bubbles formed are of a 

 bright caramel color, and they keep this color until the very last are gone, it indicates 

 presence of caramel. This difference is readily shown by comparison with known 

 pure samples. 



Lead acetate test. The coloring matter present in vanilla, or tonka, extracts is 

 almost completely removed when the dealcoholized extract is treated with a few 

 cubic centimeters of basic lead acetate solution. When caramel is present, the filtrate 

 and precipitate, if any, have the characteristic red-brown color of caramel. 



Phenylhydrazin hydrochlorid test. To 20 cc of the extract add 1 cc of zinc chlorid 

 (5 per cent solution), and then add 1 cc of a 2 per cent solution of potassium hydroxid 

 and stir the precipitate with the solution. Filter and wash the precipitate with hot 

 water. Dissolve the precipitate in 10 cc or more of a 10 per cent solution of hot 

 acetic acid, receiving this solution in an evaporating dish ; evaporate to 5 cc over 

 water bath. Neutralize the excess of acetic acid with potassium hydroxid solution 

 and divide the solution equally in two 6-inch test tubes. Add to each 5 to 10 cc of a 

 solution of phenylhydra/in hydrochlorid and sodium acetate, prepared by dissolving 

 2 grams of phenylhydra/in and 3 grams of sodium acetate in 15 cc of water. Let one 

 tube stand overnight. Heat the other on k water bath for half an hour. A brown 

 precipitate will be obtained in both cases if caramel be present. 



Fullers' earth may be substituted for zinc hydroxid. In such case, stir or shake a 

 small amount of the earth with the extract, filter and wash with cold water. Extract 

 the caramel with boiling water. Test the concentrated water solution with phenyl- 

 hydrazin as above. 



(B) LEMON EXTRACT. 



These extracts are made by the solution of oil of lemon or its more soluble constit- 

 uents in alcohol of varying strength. Oil of lemon contains nearly 90 per cent of 

 terpenes, largely d-limonene, giving the oil a rotary power of 59 to 64 circular degrees 

 at 20 F. The aromatic constituents are oxygenated bodies, the principal of which 

 is citral. The latter bodies being more soluble in weak alcohol frequently constitute 

 the chief flavoring substance present in pure extracts of the cheaper quality. 



Extracts of the highest strength and purity are made by solution of the whole oil 

 of lemon in deodorized alcohol, as described in the United States Pharmacopoeia. 

 The lowest quality of adulterated extracts may contain minute amounts of citronella 

 aldehyde or citral obtained from " lemon grass " (Andropogon titratm} , together with 

 aromatic or pungent tinctures, such as mace or capsicum. a 



1. DETERMINATION OF TOTAL RESIDUE. 



Evaporate 10 grams of the extract on a water bath at a temperature below the 

 boiling point of the alcohol. In the absence of glycerol dry to a constant weight at 



M)r. William Fivar has sn^csti-d that if a few drops of bromin water are added to 3 cc of true 

 lemon extract, the hroinin will in- almost instantaneously absorbed by the terpene present. 



