Edible Products^ 



340 



[October, 1908. 



CONTRIBUTIONS TO THE KNOW- 

 LEDGE OF CACAO FERMENTATION. 



The following paper has been compiled 

 from the Dutch, by the acting Curator, 

 Government House Gardens, A. Fred- 

 holm, Esq. It is of considerable interest 

 to Cacao planters, and explains much that 

 was previously mysterious in the " Rule 

 of Thumb " methods so generally adopted 

 in carrying on the Fermentation of 

 Cacao. 



There is still, however, the fact that the 

 quality of Cacao, though improved by 

 fermentation, depends more upon the 

 special variety cultivated, than upon 

 any method of fermentation which can 

 be employed. 



Contributions to the Knowledge of 

 the Fermentation of Cacao, 

 By Dr. J. Sack 



In Bulletin No. 10 of "Inspectie van 

 den Landbouw in West Indie " issued 

 from Surinam, January, 1908, appears an 

 article by Dr. J. Sack entitled, "Con- 

 tributions to the knowledge of the fer- 

 mentation of Cacao " recording some 

 useful researches. The following is a 

 brief synopsis of Dr. Sack's work :— 



After showing in a few concise para- 

 graphs, treating of the various modes 

 of Cacao-curing in vogue, that little 

 change has taken place therein since the 

 first shipment of Cacao was made from 

 Surinam to Holland in 1733, he suggests 

 that by the aid of scientific investigations 

 the curing may be improved so as to pro- 

 duce an article of higher market value. 

 The way to obtain this desirable end is 

 obviously by studying the fermentation 

 process by which the curing is done. 



Before entering upon a description of 

 the process itself, he asks and replies by 

 means of experiments to three questions 

 regarding the nature of, and the condi- 

 tions needed for, fermentation. 



. Question I. — Is the fermentation of 

 Cacao a Chemical or Biological process? 



In order to demonstrate whether the 

 fermentation is the result of purely Che- 

 mical reactions taking place among the 

 constituents of the pulp and the kernel 

 without the intervention of bacteria, 

 fungi or other organisms, Dr. Sack takes 

 four equal measures of Cacao numbered 

 1, 2, 3, and 4. Numbers 1 and 2 were 

 treated in the customary curing manner, 

 to number 3 was added formaldehyde, 

 and to number 4 chloroform, both pre- 

 parations destructive to life while not 

 nfluencing chemical activities. Fermen- 

 ation is always accompanied by rise of 

 emperature. In numbers 1 and 2 the 



temperature rose from 28°C. to 40°, in 

 numbers 3 and 4 it remained at 28°C. 

 Nos. 1 and 2 were now in their turn 

 treated with chloroform, with the result 

 that fermentation ceased shortly, reduc- 

 ing the temperature to 28°C. 



This experiment establishes the fact 

 that the fermentation of Cacao is prima- 

 rily not a chemical but a biological 

 process. 



Question 11. — Is the free access of air 

 necessary to the fermentation process ? 



Four cylinders provided with a drainage 

 tube were made, and in each was placed 

 four kilograms of fresh cacao beans. 

 Two were so constructed that air could 

 freely circulate among the beans, the 

 other two were completly sealed. In 

 the two first cylinders the normal fer- 

 mentation preceded, in the two which 

 were air-tight the beans rotted. 



Result. — FYee access of air necessary 

 during the fermentation process. 



Question III. — Is the rise of temper- 

 ature caused by changes in the sugary 

 contents of the pulp? 



The sweet taste of the pulp, as well as 

 the strong odour of vinegar given out 

 dux'ing the curing, points to the presence 

 of sugar in the pulp. Two lots of beans 

 were put to ferment. From one the pulp 

 was removed through washing, the other 

 lot retained the pulp. The unwashed lot 

 fermented, the washed failed to ferment. 

 After addition of syrup to the washed 

 beans, fermentation began. 



These experiments proved that the 

 sugar in the pulp is essential to the fer- 

 mentation and the incidental rise of 

 temperature. 



Dr. Sack goes on to discuss the fermen- 

 tation process itself. He divides his sub- 

 ject in two parts, viz., the fermentation 

 of the pulp which he calls external fer- 

 mentation, and the fermentation of the 

 kernel the internal fermentation. 



The external fermentation he describes 

 as follows :— As soon as the beans are 

 heaped for fermentation microscopic 

 organisms, which have the power to con- 

 vert the sugar contained in the pulp 

 first into alcohol and subsequently into 

 vinegar, enter the mass. The change 

 from sugar to alcohol is caused by 

 fungi by which sugar in the presence of 

 water is changed into alcohol by setting 

 free oxygen, a well-known process. The 

 changing of the alcohol into vinegar he 

 considers an oxidation process caused 

 by bacteria and gives chemical formula 

 C>, He + 2 = C 2 Ht 02~+ Hz O. The 

 process requires free access of air and 

 during it heat is developed. 



