Part 4 (2/2)

After 2 days 37 C. or 98 F.

After 3 days 47 C. or 115 F.

(After the third day the heat is maintained, but the temperature rises very little.)

The temperature is the simplest guide to the amount of fermentation taking place, and the uniformity of the temperature in all parts of the ma.s.s is desirable, as showing that all parts are fermenting evenly. The cacao is usually shovelled from one box to another every one or two days. The chief object of this operation is to mix the cacao and prevent merely local fermentation. To make mixing easy one ingenious planter uses a cylindrical vessel which can be turned about on its axis.

[Ill.u.s.tration: FERMENTING BOXES, JAVA.

From the last box the beans are shovelled into the was.h.i.+ng basin.

(Reproduced from van Hall's _Cocoa_, by permission of Messrs. Macmillan & Co.)]

In other places, for example in Java, the boxes are arranged as a series of steps, so that the cacao is transferred with little labour from the higher to the lower. In San Thome the cacao is placed on the plantation direct into trucks, which are covered with plaintain leaves, and run on rails through the plantation right into the fermentary. Some day some enterprising firm will build a fermentary in portable sections easily erected, and with some simple mechanical mixer to replace the present laborious method of turning the beans by manual labour.

The general conditions[1] for a good fermentation are:

(1) The ma.s.s of beans must be kept warm.

(2) The ma.s.s of beans must be moist, but not sodden.

(3) In the later stages there must be sufficient air.

(4) The boxes must be kept clean.

[1] For full details see the pamphlet by the author on _The Practice of Fermentation in Trinidad_.

_Changes during Fermentation._

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 a yeast fermentation the temperature rises unusually high (in three days to 47 degrees C.), and also that there are parallel and more important changes in the interior of the bean. The difficulty of establis.h.i.+ng a complete theory of fermentation of cacao has not daunted the scientists, for they know that the roses of philosophy are gathered by just those who can grasp the th.o.r.n.i.e.s.t problems. Success, however, is so far only partial, as can be seen by consulting the best introduction on the subject, the admirable collection of essays on _The Fermentation of Cacao_, edited by H. Hamel Smith. Here the reader will find the valuable contributions of Fickendey, Loew, Nicholls, Preyer, Schulte im Hofe, and Sack.

The obvious changes which occur in the breaking down of the fruity exterior of the bean should be carefully distinguished from the subtle changes in the bean itself. Let us consider them separately:--

(_a_) _Changes in the Pulp._--Just as grape-pulp ferments and changes to wine, and just as weak wine if left exposed becomes sour; so the fruity sugary pulp outside the cacao bean on exposure gives off bubbles of carbon dioxide, becomes alcoholic, and later becomes acid. The acid produced is generally the pleasant vinegar acid (acetic acid), but under some circ.u.mstances it may be lactic acid, or the rancid-smelling butyric acid. Kismet! The planter trusts to nature to provide the right kind of fermentation. This fermentation is set up and carried on by the minute organisms (yeasts, bacteria, etc.), which chance to fall on the beans from the air or come from the sides of the receptacle. One yeast-cell does not make a fermentation, and as no yeast is added a day is wasted whilst any yeasts which happen to be present are multiplying to an army large enough to produce a visible effect on the pulp. _Any_ organism which happens to be on the pod, in the air, or on the inside of the fermentary will multiply in the pulp, if the pulp contains suitable nourishment. Each kind of organism produces its own characteristic changes. It would thus appear a miracle if the same substances were always produced. Yet, just as grape-juice left exposed to every micro-organism of the air, generally changes in the direction of wine more or less good, so the pulp of cacao tends, broadly speaking, to ferment in one way. It would, however, be a serious error to a.s.sume that exactly the same kind of fermentation takes place in any two fermentaries in the world, and the maximum variation must be considerable. As the pulp ferments, it is destroyed; it gradually changes from white to brown, and a liquid (”sweatings”) flows away from it. The ”_sweatings_” taste like sweet cider. At present this is allowed to run away through holes in the bottom of the box, and no care is taken to preserve what may yet become a valuable by-product. I found by experiment that in the preparation of one cwt. of dry beans about 1-1/2 gallons of this unstable liquid are produced. In other words, some seven or eight million gallons of ”sweatings” run to waste every year. In most cases only small quant.i.ties are produced in one place at one time. This, and the lack of knowledge of scientifically controlled fermentation, and the difficulty of bottling, prevent the starting of an industry producing either a new drink or a vinegar. The cacao juice or ”sweatings” contains about fifteen per cent. of solids, about half of which consists of sugars. If the fermentation of the cacao were centralised 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.

[Ill.u.s.tration: CHARGING THE CACAO ON TO TRUCKS IN THE PLANTATION, SAN THOMe.]

[Ill.u.s.tration: CACAO IN THE FERMENTING TRUCKS, SAN THOMe.

The covering of banana leaves keeps the beans warm.]

The planter decides when the beans are fermented by simply looking at them; he judges their condition by the colour of the pulp. When they are ready to be removed from the fermentary they are plump, and brown without, and juicy within.

(_b_) _Changes in the Interior of the Bean._--What is the relation between the comparatively simple fermentation of the pulp and the changes in the interior of the bean? This important question has not yet been answered, although a number of attempts have been made.

As far as is known, the living ferments (micro-organisms) do not penetrate the skin of the bean, so that any fermentation which takes place must be promoted by unorganised ferments (or enzymes). Mr. H.C.

Brill[2] found raffinase, invertase, casease and protease in the pulp; oxidase, raffinase, casease and emulsinlike enzymes in the fresh bean; and all these six, together with diastase, in the fermented bean. Dr.

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