Vol. XVIII. No. 444. 



THE AGRICULTURAL XEWS. 



1*1 V 



SCIENCE IN CACAO PRODUCTION. 



An interesting article by Mr. A. W. Knapp, taken from 

 the Jotirnal of the Society of Chemical Industry, appears 

 in the Porlof-Spain (?a3e<?e, April 6, 1919. Much of this 

 article is reproduced below. 



There is a great field for thu application of physical and 

 chemical knowledge to the production of the raw materials of 

 the tropics In one or two instances notable advances have 

 been made- Thus the direct production of a white sjgar (as 

 now practised in Java) at the tropical factory will have far- 

 reaching etfects, but with many tropical products the methods 

 practised are as ancient as they are haphazard. Like all 

 methods founded on long experience, they suit the environ- 

 ment and the temperament of the people who use them, so 

 that the work of the scientist in introducing improvements 

 requires intimate knowledge of the conditions, if his sugges- 

 tions are to be adopted. The various Departments of Agri- 

 culture are doing splendid pioneer work, but the full harvest 

 of their sowing will not be reaped until the number of tropi. 

 cally educated agriculturists has been increased by the found- 

 ing of three or four agricultural colleges and research labora- 

 tories in equatorial regions. 



As an illustration of the above generalization of the 

 many ways in which science may be expected to improve the 

 production of tropical products, the cacao industry is addu- 

 ced. In the first place, improvement of yield should be kept in 

 view. At the present time the average yield per tree is surpris- 

 ingly small, being about li ft>. to 2 lb. a year, and the total 

 world production is about 290,000 tons a year. By scientific 

 agriculture, taking a conservative estimate, the average yield 

 per tree cotild be raised to GB)-, and the total production to 

 over a million tons a year. 



Improvement also in methods of harvesting the crop is to 

 be sought for. The pods are cut from the tree by knives on the 

 end of poles, a ditlicult operation. Considerable ingenuity 

 has been exercised to produce a gatherer which will sever 

 the pod stems and yet be 'fool-proof,' but the ideal method 

 of collecting has yet to be found. 



The pods have to be cut open after they are picked, and the 

 juicy beans removed. This is generally done with a cutlass. 

 What is needed is a knife which will cut the husk of the 

 pod without injuring the beans within. The placenta (the 

 part of a plant to which the seeds are attached) contains a 

 fair percentage of pectin, of which no use is made. 



.Many <juestions with regard to the preparation of the 

 cacao tor the market need scientific investigation. The 

 question of fermentation, in the first place, and how this is 

 best to be accompiished needs much consideration. 



The seeds or beans are covered with a juicy pulp and 

 would rot if they were not dried. The best way to remove 

 the pulp is to allow it to ferment: this occurs naturally on 

 exposure to air, as with grape juice. The effects of fermenta- 

 tion are varied and all advantageous — the bean becomes 

 more easy to dry, and on drying becomes crisp; it develops a 

 richer colour, and on roasting, a firmer aroma and flavour. 

 Fermented cacao always fetches a higher price than unfer- 

 mented cacao from the same place, but fermentation is by no 

 njeans universally practised. Hence one finds on the market 

 considerable ([uantities of cacao which contain mouldy beans, 

 for unfermented cacao readily gets mouldy; this is a serious 

 loss to the world. Fermentation is'not^carried on anywhere in a 

 scientific manner; everywhere the cacao is at the mercy of 

 the chance organisms in the air. The quality of the cacao 

 produced varies, and the quality is reflected in the prices 

 obtained ; thus the Food .Controller has fixed the price of 

 British West African cacao at 65«. a twt., GreoiMla at 85«. a 



cwt., and Ceylon at 100s. a cwt. The quality of any cacao is 

 the result of the botanic variety or 'breed' plus the treatment 

 it receives in preparation for the market. Now Grenada and 

 Ceylon cacaos are obviously different in 'breed', so that Grena- 

 da cannot hope by fermentation, however scientific, to get 

 the Ceylon bean. The line of improvement perhaps for 

 Grenada is to try the planting and rearing of the more delicate 

 Ceylon type of cacao. Grenada beans are very carefully pre- 

 pared (if not scientifically, yet with great art) and give prac- 

 tically 100 per cent, perfect beans. This is the explanation 

 of the higher prices given for Grenada cacao over that from 

 West Africa. 



No entirely satisfactory theory of the changes in cacao 

 due to fermentation has yet been established. It is known 

 that the sugary pulp outside the beans ferments in a similar 

 way to other fruit pulp, save that for yeast fementation the 

 temperature rises usually high (in three days to 47' C); and 

 also that there are parallel and more important changes in 

 the interior of the bean. 



But there is still a vast amount of work to be done 

 before the chemist will be in a position to obtain the more 

 desirable aromas and flavours. Having found the necessary 

 conditions, scientifically trained overseers will be required to 

 carry them out, and for this they will need to have under 

 their direction arrangements for fermentation designed on 

 correct principles, and allowing some degree of control. 



It is not always remembered that the beans and pulp 

 contain tannic and acetic acids. As the present overseers 

 generally have no knowledge of chemistry, they do not 

 understand, for instance, how the appearance of the cacao 

 may be spoiled by the iron nails used in constructing the 

 fermentation boxes, when acted on by those acids. 



This leads to the question of the use of the juice which 

 runs to waste, and it cannot be less than eight million 

 gallons a year. This juice or 'sweating' contains about 15 pet 

 cent, of solids, about half of which consists of sugars. If the 

 fermentation of the cacao were centralized in the various 

 districts, and conducted on a large scale under a chemist's 

 control, the sugars could be obtained, or an alcoholic liquid, or 

 a vinegar could easily be prepared. This acid liquid might 

 also be used for the coagulation of rubber latex. 



Drying is the only point in cacao production which has 

 received mucb attention from the engineer. VVhether the 

 cacao has been fermented or not, it has to be dried to prevent it 

 going mouldy. The common practice is to spread it on 

 platforms or mats, and dry it in the sun. In a few places 

 where sun-drying is difficult, drying machines are slowy 

 comin.!,'- into vogue, and doubtless the general principles of 

 drying are well understood, but to make a really satisfactory 

 drying machine one must have knowledge of the chemical 

 and physical nature of the raw product. 



It has been pointed out by several observers that during 

 sun-drying the changes due to fermentation continue, par- 

 ticularly the change due to an oxide, i.e. the oxidation of 

 a tannin which results in the removal of the astringent 

 taste, and the development of a brown colour. With drying 

 machines the conditions are often unfavourable to this action. 

 This is one of the reasons why, at present, manufacturers of 

 cocoa somewhat prefer the ?un-dried to the maehiae dried 

 beans. 



Criticism could be made of the various subsidiary 

 processes (washing, claying, polishing, etc.) to which the 

 beaas are subjected in dift'erent countries, but sufficient has 

 been said to give an idea ol the wide field for research, and of 

 the opportunities for the application of known fatts to 

 this industry. 



