XXII. METHODS FOB THE ANALYSIS OF COFFEE. PROVISIONAL. 



RAW COFFEE. 



The proximate examination of raw coffee is of no value in determining its 

 quality, since no substitutes are on the market, and as it is not adulterated 

 with other substances for the purpose of increasing its volume or weight, the 

 proximate analysis is not made. 



The inferior grades are sometimes colored to imitate the better grades. Pig- 

 ments, such as ocher, litharge, lead chromate, and chromic oxid, and organic 

 colors, such as indigo, turmeric, azo yellow, malachite green, methyl green, etc., 

 have been used for this purpose. The mineral colors can be identified in the ash 

 or removed from the bean by shaking with water, in which case the soluble 

 colors can be identified in the solution and the insoluble ones in the residue. 



BOASTED COFFEE. 

 1. Examination of the Whole Beans. 



Examine megascopically in order to detect foreign substances. Artificial 

 coffee beans are apparent from their exact regularity of form. Coffee pellets 

 are made from roasted wheat mash and are of a brown color, possessing a very 

 characteristic ellipsoidal form. Roasted legumes and lumps of chicory are 

 sometimes present and are easily identified by the practiced eye. Coffee is 

 glazed by treating the raw bean with molasses, sugar solution, glycerin, or fats 

 and waxes, and then roasting. 



2. Detection of Sugar Glazing- Stutzer and Reitnair Method. 



Treat 20 grams of the whole beans with 500 cc of water in a liter flask and 

 shake vigorously for five minutes. Bring the volume to the mark with water, 

 mix, filter, and determine the solids and ash in 50 cc of the filtrate. 



3. Detection of Glycerol. 



Proceed as directed under " XIII. Wine," section 3, page 83, using a portion 

 of the filtrate from the preceding determination. 



4. Detection of Fats and Waxes Spath Method. 6 



Treat 100 to 200 grams of the beans with low boiling petroleum ether for ten 

 minutes, pour off the petroleum ether and repeat the process. Filter the com- 

 bined petroleum ether extracts, evaporate, and determine the saponiflcation 

 number and index of refraction of residue, as directed under " XIX. Edible 

 Fats and Oils," pages 131 and 137. 



5. Preparation of Sample. 

 Grind the sample and pass it through a sieve having holes 0.5 mm in diameter. 



Pharm. Centralh., 22: 134. 



Forscbungsberichte Uber Lebensmlttel, 1895, 2 : 223. 



152 



