COFFEE 647 



folding of the endosperm, and in which is contained the parchment- 

 like seed-coat; hard, easily broken, and containing at the basal por- 

 tion of the endosperm, a small embryo; odor distinct, aromatic; 

 taste pleasantly bitter. 



Inner Structure. Seed-coat fragmentary on the surface of the 

 seeds, and parchment-like in the groove and characterized by the 

 presence of numerous stone cells, occurring singly or in small groups, 

 from 0.100 to 1 mm. in length and 0.015 to 0.050 mm. in breadth, 

 the cells varying in size and in form, and possessing relatively thick, 

 porous and strongly lignified walls; endosperm large, composed of 

 irregularly thickened, porous cellulose walls, and containing sugar, 

 tannic acid, a fixed oil, caffeine and occasionally aleurone grains; 

 embryo small and usually bursts through the endosperm, on soaking 

 the green seeds overnight. 



Powder. Dark brown; characteristic fragments of seed-coat 

 made up of parenchyma and spindle-shaped stone cells, from 0.2 to 

 1 mm. in length and from 0.015 to 0.050 in width, the latter occurring 

 singly or in pairs, having more or less thickened porous walls. The 

 cells of the endosperm have brownish-colored, porous walls, about 

 0.010 mm. in thickness, and contain oil, aleurone and starch. Ground 

 coffee varies in the fineness of the particles, which are lighter than 

 water and float on the surface. This is an important distinction 

 between genuine coffee and the " substitutes " or " imitation " 

 products which sink on being mixed with water. 



Constituents. Coffee seeds contain from 1 to 2 per cent of caf- 

 feine; from 3 to 5 per cent of tannin; about 15 per cent of glucose 

 and dextrin; 10 to 13 per cent of a fatty oil consisting chiefly of olein 

 and palmitin; 10 to 13 per cent of proteins; and yield 4 to 7 per cent 

 of ash. The official caffeine is derived in part from coffee seeds. For 

 description, tests and methods of detecting caffeine, see p. 436. 



In the roasting of coffee there is a change in the physical character 

 of the seeds, as well as a change in some of the constituents The 

 aroma is supposed to be due to an oil known as coffeol, which is said 

 to be a methyl ether of saligenin. 



Coffee increases in weight in storage. In paper bags and cartons, 

 the maximum increase in weight is reached in the fall months. 

 During the winter months there is a loss in weight, while during the 

 spring and summer there is little change. (Doolittle and Wright, 

 Amer. Jour. Pharm., 1915, p. 524.) 



Coffee Hulls, also known as Sultan or Sacca coffee, are sometimes 

 si bstituted for coffee. These consist of the outer layer of the peri- 

 carp and are characterized by a layer of somewhat curved, elongated 



