128 COCOA AND CHOCOLATE 



roasting machines used at Bournville. It resembles an 

 ordinary coffee roaster, the beans being fed in through 

 a hopper and heated by gas in the slowly revolving 

 cylinder. The beans can be heard lightly tumbling 

 one over the other, and the aroma round the roaster 

 increases in fullness as they get hotter and hotter. The 

 temperature which the beans reach in ordinary roas ting 

 is not very high, varying round i35C. (275F), and 

 the average period of roasting is about one hour. The 

 amount of loss of weight on roasting is considerable 

 (some seven or eight per cent.), and varies with the 

 amount of moisture present in the raw beans. 



There have been attempts to replace the aesthetic 

 judgment of man, as to the point at which to stop 

 roasting, by scientific machinery. One rather interest- 

 ing machine was so devised that the cacao roasting 

 drum was fitted with a sort of steelyard, and this, when 

 the loss of weight due to roasting had reached a certain 

 amount, swung over and rang a bell, indicating dram- 

 atically that the roasting was finished. As beans vary 

 amongst other things in the percentage of moisture 

 which they contain, the machine has not replaced the 

 experienced operator. He takes samples from the 

 drum from time to time, and when the aroma has the 

 character desired, the beans are rapidly discharged 

 into a trolley with a perforated bottom, which is brought 

 over a cold current of air. The object of this refine- 

 ment is to stop the roasting instantly and prevent even 

 a suspicion of burning. 



After roasting, the shell is brittle and quite free from 

 the cotyledons or kernel. The kernel has become 

 Mossy and friable and chocolate brown in colour, and 

 it crushes readily between the fingers into small angu- 

 lar fragments (the " nibs ' of commerce), giving off 

 during the breaking down a rich warm odour of 

 chocolate. 



(d) Removing the Shells. 



It has been stated (see Fatty Foods, by Re vis and 



