322 



THE AGRICULTURAL NEWS. 



October 11, 1913. 



produces the desired change of colour, and causes 

 the conversion of astringent substances. Thus 

 the fermentation proper is considered to be only of 

 secondary importance. Nicholls, Preyer, Bainbridge 

 and Davies, on the other hand, attach less importance 

 to the conversion of astringent substances, and contend 

 that there is a penetration of certain products of the 

 external fermentation into the interior of the seed. 

 Even Schulne recognizes that liquid substances are 

 absorbed during fermentation. 



The importance of the conversion of astringent 

 substances is supported experimentally by the fact that 

 the changes essential to the preparation of cacao may 

 take place without fermentation if the germs in the 

 beans are killed imder conditions that leave the 

 enzymes unimpaired. The reporb of brokers, never- 

 theless, appear, at present, to indicate that cacao so 

 treated is not, other things being equal, of such good 

 quality as cacao fennented in the ordinary way, though 

 of much better quality than cacao not treated at 

 all. In support of the beneficial effect of external 

 fermentation on the (juality of the beans, Hudson says, 

 'the higher the temperature attained and maintained 

 for some days by primary natural fermentation, the 

 better the class of cacao turned out.' So that, taking 

 all these views into consideration, one is inclined to the 

 opinion that, under existing conditions, the fermentation 

 of the pulp does serve a useful purpose, not merely in 

 regard to its removal, not merely because of the action 

 of heat and acid on the oxidation of the seed, but also 

 on accounc of the penetration of certain substances 

 into, or at least their deposition on, the beans. 



It is not maintained, however, that fermentation 

 •will always be necessary. On this point we are in 

 agreement with Sir (ieorge Watt. And the view may 

 by expressed that it will be the introduction of some 

 mechanical system of curing that will most ertectivcly 

 meet the existing economic requirements of the cacao 

 industry, namely, the output of uniform produce. 

 Quite lately, in the Agricultural Nexus, a brief 

 account was given of Perroli's efforts to remove the 

 pulp of cacao seeds by means of an alkali, and tn 

 induce the necessary changes in the sterilized seed 

 reduced to powder. Success seems to have followed 

 these efforts to some extent, and further investigation 

 along this line is to be encouraged. 



Assuming then, that, for the present, fermentation 

 is desirable, what are the best ways of conducting the 

 operation and what are the improvements that may 

 be introduced? On these questions the book under 



revie» provides a great deal of information. Schulte 

 recommends the Cameroon system of fermenting on 

 floors as is done with malt in a brewery, though it may 

 be pointed out here that the main contention of 

 Schulte is that his oxidation process should be substi- 

 tuted for ordinary fermentation. 



In spite of being somewhat drawn out, perhaps the 

 best practical information on methods of fermentation is 

 given by Hudson, who like most of the writers, attaches 

 great importance to the 'changing' of the seed. As 

 already indicated, Hudson considers the maintenance of 

 a high temperature essential. (The temperature of even 

 the bottom of the box should never fall below 100 F.) 

 In this he is not in agi-eement with Hart, who has 

 expressed the view that too high a temperature during 

 natural fermentation is injurious. 



A point of much interest is raised by Nicholls in 

 regard to the inoculation of the bear.; with the yeast 

 that causes the change of sugar into alcohol. His 

 object is not to introduce a pure culture of the organ- 

 ism as has been proposed by Preyer, but merely to 

 increase the amount, and to provide a mineralc ulture 

 medium. Most of the writers support Nicholls' sug- 

 gestion, but indicate the necessity for further investi- 

 gation. In continuation of the subject of these fermen- 

 tation organisms, Nicholls apparently contends that the 

 fly known as Drosophila mclanogaster conveys yeast to 

 the fermenting cacao, whereas Bainbridge and I )avie8 

 refer to this insect as a carrier of the acetic organism 

 only. Probably it conveys both. 



Closely related to the actual process of fermen- 

 tation is the drying of cacao. Hudson does not seem 

 to attach much importance to sun-drying, whereas 

 several of the other writers do, on the score that 

 the jirocess works slowly, so that the air has time to 

 penetrate into the bean, and to complete the process of 

 oxidation. As regards drying machines, Hudson's 

 essay provides very useful information. In this con- 

 nexion the possibility of an extended employment in 

 the future of the vacuum drier is of interest. The 

 same writer's remarks on polishing machines should 

 also be noted. 



Nowadays, every manufacturing process must have 

 its by-products. The fermentation of cacao, we are told, 

 cannot be an exception to this rule. The world's output 

 of cacao is, at present, about 227,500 English tons. 

 According to Hudson, the fermentation of 200 lb, of 

 cacao yields 2 gallons of vinegar, which would mean 

 that 227,500 tons produce 5,096,000 gallons, valued 



