148 The Fermentation of Cacao 



As a further check the residue, at another 

 test, was heated for five minutes to 100 C. 

 before adding the violet mass ; here after 

 standing for days there was not the slightest 

 trace of change of colour. 



From these tests it follows that the dis- 

 colouration of the beans, which die at a tem- 

 perature of about 45 C. during the fermentation, 

 is caused by a substance contained in the seed 

 itself, and which must be an enzyme, seeing 

 that it can be destroyed by boiling heat, is 

 precipitated by alcohol, and causes the dis- 

 coloration by the medium of a minute quantity. 

 The temperature at which 'the enzyme is 

 destroyed appears to be somewhere about 

 70 C. 



For the purpose of ascertaining the activity 

 of the enzyme-containing residue, a few further 

 tests were made. In these it was noticed that 

 cane-sugar did not split, an invertase thus 

 appeared to be lacking. Amygdalin, however, 

 did so. 



This observation gave us an idea as to the 

 nature of the reaction which causes the beans 

 to turn brown. 



In the beans, the above-mentioned glucoside 1 

 does not exist, but another, i.e., cacaonine, is 



1 By glucosides are understood those substances 

 which by the action of acids, alkalis or enzymes become 

 divided, so that in addition to more or less compound 

 bodies a kind of sugar, usually dextrose, forms. Glu- 

 cosides appear almost exclusively as plant substances. 



