144 COFFEE 



yellow or brown liquid; sample mostly sinks if adulterated (prob- 

 ably with chicory and cereals). 



5. Alcoholic Treatment for removal of organic coloring mat- 

 ters, sugar, egg-albumen, etc., as under "Whole Bean Treatment." 



B. Chemical Analysis: 



1. Chicory Detection: 



Procedure: — Boil 10 grms. sample with 250 c.c. of water. Strain 

 liquid. Precipitate with slight excess of basic lead acetate. Allow 

 precipitate to settle. 



Test: — Pure coffee — supernatant liquid, colorless. Presence of 

 chicory — supernatant liquid colored; the tint is roughly indicative 

 of the proportion of chicory present. 



2. Starch Test (indicative of such adulterants as beans, peas, 

 acorns, and all cereals) : 



Procedure : — Exhaust sample with ether to remove fat. Decolor- 

 ize with alcohol. Boil sample for few minutes with 10 parts 

 water. Allow to become cold. Add some dilute H2SO4. Drop 

 in cautiously, with agitation, a solution of potassium permanganate 

 until coloring matter is nearly destroyed. Strain liquid or decant 

 from insoluble matter. Decolorize with animal charcoal. Add 

 solution of iodine. 



Test: — Blue coloration if positive. As small a quantity as 1% 

 can be detected by this method. Genuine coifee is free from ready 

 formed starch. 



3. Ash Content as means of detecting adulteration: 



(a) Pure coffee — very nearly white in color; 3.5 to 4.5% 

 (rarely 5%) in quantit)^ 



(b) Adulterated coffee — often tinted ash; red tint indicates 

 some iron compound as adulterant ; high ash percentage. 



(c) For constituents of Pure Coffee Ash, see Section under 

 "The Chemistry of Coifee," page 157 et seq. 



4. Caffeine Content: 



U. S. and European substitutes and adulterants are devoid of 

 any caffeine ; therefore the absence of caffeine assures complete sub- 

 stitution. 



(a) Caffeine Detection by the "Murexid Test" with the ma- 



