[Illustration: CHARGING THE CACAO ON TO TRUCKS IN THE PLANTATION, SAN THOMÉ.]
[Illustration: CACAO IN THE FERMENTING TRUCKS, SAN THOMÉ. 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. Fickendey says: "The object of fermentation is, in the main, to kill the germ of the bean in such a manner that the efficiency of the unorganised ferment is in no way impaired."
[2] _Philippine Journal of Science_, 1917.
From my own observations I believe that forastero beans are killed at 47 degrees C. (which is commonly reached when they have been fermenting 60 hours), for a remarkable change takes place at this temperature and time. Whilst the micro-organisms remain outside, the juice of the pulp appears to penetrate not only the skin, but the flesh of the bean, and the brilliant violet in the isolated pigment cells becomes diffused more or less evenly throughout the entire bean, including the "germ." It is certain that the bean absorbs liquid from the outside, for it becomes so plump that its skin is stretched to the utmost. The following changes occur:
(1) _Taste._ An astringent colourless substance (a tannin or a body possessing many properties of a tannin) changes to a tasteless brown substance. The bean begins to taste less astringent as the "tannin" is destroyed. With white (criollo) beans this change is sufficiently advanced in two days, but with purple (forastero) beans it may take seven days.