November, 1910,] 



407 



Edible Products, 



Fermentation is always accompanied by 

 rise of temperature. In numbers 1 and 

 2 the temperature rose from 28°0. to 

 40°, in numbers 3 and 4 it remained at 

 28°0. 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 established the fact 

 that the fermentation of cacao is 

 primarily not a chemical but a biological 

 process. 



Question II.— Is the free access of air 

 necessary to the fermentation process ? 



Four cylinders provided with a drain- 

 age tube were made and in each was 

 placed 4 kilograms of fresh cacao beans. 

 Two were so constructed that air could 

 freely circulate among the beans, the 

 other two were completely sealed. In 

 the two first cylinders the normal fer- 

 mentation proceeded, in the two which 

 were air-tight the beans rotted. 



Result : Free 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 

 during 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 prove that the 

 sugar in the pulp is essential to the 

 fermentation and the incident rise of 

 temperature. 



Dr, Sack goes on to discuss the fer- 

 mentation process itself. He divided 

 his subject in two parts, viz : the fer- 

 mentation of the pulp, which he calls 

 external fermentation, and the ferment- 

 ation of the kernel, the internal kernel. 



The external fermentation he des- 

 cribes as follows : As soon as the beans 

 are heaped for fermentation microscopic 

 organisms, which have the power to 

 convert 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 alcohol into vinegar he 

 considers an oxidation process caused by 

 bacteria and gives chemical formula 

 02, H 6 O + O2 = C2 Ri Oi + H O. 

 The process requires free access of air 

 and during it heat is developed. 



The internal fermentation shows as 

 follows : So long as the seed remains 

 alive, no chemical process seems to take 

 place, but, as soon as dead, such pro- 

 cesses set in. The temperature devel- 

 oped by the fermentation of the pulp 

 causes the death of the contents of the 

 kernel. 



He made the following experiments to 

 establish the temperature at which 

 death took place. To secure for the 

 experiments well germinated and uni- 

 form seeds especial care was taken. Ten 

 seeds were exposed for three hours to a 

 temperature of 43° C, all germinated. 

 After an exposure lasting six hours four 

 germinated but with unhealthy looking 

 sprouts. When exposed nine hours one 

 germinated. Of ten seeds which were 

 exposed for six hours to a 44 3 C temper- 

 ature none germinated. 



As the temperature usually devel- 

 oped during the external fermentation 

 reaches 45° C. and is continued for at 

 least four days it is fairly certain that 

 all the seed-germs are killed and the 

 internal fermentation has set in. 



He next investigates the change of 

 colour taking place in the kernels. The 

 change from purple in the unfermented 

 bean to brow n in the fermented appears 

 to be the result of some agent or agency 

 present in the kernel itself as no direct 

 connection seems to exist between the 

 two (external and internal) fermentation. 

 This agent is an enzyme and a series of 

 experiments are concluded to prove this 

 assertion. A comprehensive under- 

 standing of the^subject can be gained by 

 noting the results of these experiments 

 without going into detailed descrip- 

 tions of them. 



If kernels are finely pulverised the 

 change of colour takes place, free access 

 of air being essential. 



If the kernels are previously steeped 

 in boiling water no colour-change 

 occurs. 



If to the steeped mass some un- 

 steeped kernels are added the colour 

 changes. 



The enzyme manifests the greatest 

 activity at a temperature ranging from 

 45° C. to 00° C. (optimum temperature). 



Through the usual method of washing, 

 Alteration and alcoholic precipitation a 

 culture of the enzyme was made. From 

 one kilo of beans about one-half gram of 

 culture was obtained. 



When some of this enzyme culture 

 was added to a quantity of pulverised 

 beans, which had been immersed in 

 boiling water colouring took place in one 

 hour. 



