30 COCOA 



CHAJ'. 



These figures show the low percentage of mineral 

 constituents in the seeds, and this makes the total 

 quantity of such constituents in the yearly crop com- 

 paratively small. 



Interesting chemical differences between the two 

 cocoa types investigated by Professor Harrison cannot 

 be deduced from the figures just given ; but it is an 

 interesting fact that many substances contained in the 

 kernels are also contained in the cuticles and pulp, 

 though in smaller quantities. This is especially the 

 case with theobromine, caffeine, fat, astringent matters 

 and cocoa-red, and is the explanation why the cuticles 

 are used as a substitute for, and as a means of 

 adulterating, the kernels. 



CHANGES DURING FERMENTATION 



In Chapter VII. the cause and the principal effects 

 of fermentation are discussed. Some of the chemical 

 processes involved may be dealt with here. 



Fermentation is always started by the action of a 

 yeast organism which changes the sugar of the pulp 

 into alcohol and carbonic acid. The sugar contained in 

 the pulp is principally ordinary cane-sugar or saccharose 

 (C 12 H 22 O n ). This is first split up by the invertase of 

 the yeast into dextrose (the sort of sugar contained in 

 grapes and other fruits), according to the equation : 



Saccharose. Water. Dextrose. 



This process is closely followed by the splitting up of 

 the dextrose into alcohol and carbon dioxide, according 

 to the equation : 



C 6 H 12 6 = 2C 2 H 6 + 2C0 2 



Glucose. Alcohol. Carbon dioxide. 



The alcohol is again oxidised into acetic acid by a second 

 organism, a bacterium, the chemical process being 

 indicated by the equation : 



