128 COFFEE 



sizes. As the beans are transferred by suction to a milling-machine, 

 the stones and other debris drop out into a waste-container. The 

 process of milling removes the silver skin and w^hatever parchment 

 may have escaped extraction during the plantation treatment. Blend- 

 ing is now accomplished by weight, a method which insures uni- 

 formity. The blended coffee is then roasted in perforated cylinders 

 which revolve continuously over a furnace fire which maintains a 

 moderate and constant temperature in order to preserve the aroma 

 of the coffee. Excessive heat is avoided as it would decompose the 

 acid, the gum, and the resinous contents. 



The leading coffee-houses in the United States roast in quantities 

 of two hundred and ten to two hundred and sixty pounds per cylinder 

 at a time. The best results favor the lower quantity. The period 

 of roasting varies somewhat; but the customary time ranges from 

 twenty to thirty minutes according to the dryness of the raw beans. 

 The experienced roasters are able to recognize the critical point by 

 the color of the beans which in general is more reddish than brown 

 and never black, and by the aroma emitted. When the beans are 

 sufficiently roasted, the cylinder is immediately emptied, and the 

 steaming beans pass into a shallow truck which is air-cooled from 

 below. The beans are shovelled about until they cease to steam, and 

 are then allowed to cool without agitation. The sudden contact of 

 the coffee with the air from above and below causes the cessation of 

 the evaporation process and the consequent concentration of the vola- 

 tile oil in the beans. When cooled, the coffee-beans are packed whole, 

 or are ground and placed in bags or tins, in which form they reach 

 the consumer. 



It is desirable to roast American and West Indian coffees separately 

 from Mocha coffee if they are to be blended, as Mocha coffee requires 

 less roasting. Over-roasting causes it to lose its volatile properties. 

 It has reached its critical stage when it becomes a brown, cinnamon 

 color, while American and West Indian coffees, in which dampness 

 predominates over the oily principle, must be roasted until a chestnut 

 brown hue is attained. 



Regardless of the care practiced by the commercial houses in her- 

 metically sealing their retail containers, ground coffees always lose a 

 considerable part of their aromatic strength and usually in direct 



