The Manufacture of Chocolate and other Cacao Preparations - Paul Zipperer

Table 17[93].

	Maracaibo	Caracas	Trinidad	Machala Guayaquil	Porta Plata
	Per cent
Ash dried at 100° C.
I. insoluble in dilute hydrochloric or nitric acid:
a) Volatile dessicated at 100° C.	0·113	0·421	0·979	0·306	1·247
b) Fixed at red heat	1·917	47·711	29·315	37·662	51·513
II. Soluble in dilute hydrochloric or nitric acid:
c) Potassium oxide K₂O	31·517	11·812	25·866	23·117	12·174
d) Sodium oxide Na₂O	4·188	3·298	2·726	1·210	2·780
e) Calcium oxide CaO	10·134	4·458	5·097	3·503	4·401
f) Magnesium oxide MgO	9·546	4·703	5·206	4·837	4·090
g) Ferric oxide Fe₂O₃	0·647	0·931	0·339	0·958	0·462
h) Aluminium oxide Al₂O₃	0·281	1·554	0·710	1·854	1·046
i) Silicic acid SiO₂	1·180	7·975	2·416	4·321	6·780
k) Phosphoric anhydride P₂O₅	9·068	7·630	4·703	7·288	7·242
l) Sulphuric anhydride SO₃	3·041	1·478	3·398	1·741	2·012
m) Chlorine Cl	1·005	0·220	1·022	0·255	0·444
n) Carbonic anhydride CO₂	25·454	5·399	16·290	11·834	4·247
o) Water H₂O	2·135	2·499	2·263	1·171	1·662
p) Oxygen O equivalent to chlorine	0·226	0·049	0·290	0·057	0·100

As evidenced in the preceding examples, data as to the constituents of the cacao husk deviate considerably with different authors. Laube and Aldendorff, for instance, found 14-20 percent, while Zipperer obtained 12-18 percent of husks.

These discrepancies are mainly due to adhering sand and ferruginous earth collected during the drying and fermenting processes. If the beans are carefully collected and kept free from earthy substances, the percentage of husks as against that of the bean will appear much lower; it is, indeed, now possible to obtain properly treated beans which contain on an average only some 10 percent of husks, such as Ariba and Machala. The husks of these two varieties are exceedingly woody, and their amount sometimes reaches 15 per cent. The latest machinery for cleaning the beans effects so complete a separation of the husks from the kernel that very little of the former remains in the finished cacao preparation (less than 1 percent in thin-shelled beans and no more than 2 percent in thick-shelled beans such as Ariba). For some years it was not possible to effect so thorough a removal of the husk, so that there was always found an appreciably large amount of shells in the finished preparations, which rendered it difficult to detect adulteration. As, however, the quantity of ash present in the husk is double that in the kernel, it was possible to form an opinion as to the intentional admixture of shells from the increase of ash in cacao preparations. Hence the ash was always required to be determined when adulteration was suspected. Under existing conditions the addition of a quantity of shells sufficient to increase the percentage of ash present in the powder or chocolate is scarcely practicable, so that, for the purpose of detecting small additions, other methods must be resorted to, such as the estimation of the crude fibre or silica in the ash[94] with the aid of the microscope, in which it is possible to easily distinguish the forms of the cotyledon (kernel) mass and those of the husk. The diagram on page 14, Fig. 3, clearly shows the elementary forms of the cacao husk as represented by Mitscherlich. It illustrates a longitudinal section of the husk of Bahia beans, enlarged about 500 times, with six different cell elements in alphabetical order. First the compressed cells of the epidermis are to be seen on the exterior, in several parallel series and succeeded by moderately broad and thin-walled cellular tissue of the parenchyma, which sometimes presents large empty spaces (sch) the results of the loosening of the cell walls through the formation of mucilage. This cellular tissue (lp) is also permeated by bundles of spiral vessels (gfb), which, with the dry cells, are characteristic of the husk, as they exist only in very small quantity in the kernel. Then follow parallel rows of cells (lp) resembling epithelial cells; next comes a layer of cells with thick walls, the dry cells (st) and finally several rows of elongated ones (lp). The silver membrane (is) interposes between the husk and the kernel, fragments of which remain adhering to the shell after separation of the latter.

To conclude, we find that the husk of the cacao bean consists of the inner coat of fruit, called endocarp and other parts of the fruit covering, as well as the skin of the seed[95]. The following layers may be distinguished;

1. The pulp, (f in fig. 3) fragile large cells with frequent hiatus;

2. the endocarp (fe), a single layer of fragile, very narrow and irregularly arranged cells, but without hiatus;

3. the epicarp, or skin (se), polygonal and extended cells, with an outer wall of some thickness.

4. the parenchyma or cellular tissue (lp), consisting of large and multiform cells, with vascular bundles (gfb), the large mucilagenous or slime cells (sch) and

5. the sklerogenous or dry cells (st), a single layer of vessels shaped like a horseshoe, and thickening towards the interior, and in conclusion

6. the silver membrane (is), belonging to the earlier inner coat of fruit, and consisting of two single rows of fat-bearing cells.

In examination of the husks of the plane surface enlarged 160 times (fig. 8), it will be noticed that the characteristic epidermis (ep) consists of large and rather elongated but irregular polygonal cells. Frequently on the epidermis may be remarked a delicate network of the cells constituting the fruit pulp (p). Beneath the epidermis lies a very delicate transverse cellular layer (qu) followed by the parenchyma, as already stated. The remaining elementary forms are not readily observed on a plane surface but only in section, though we adjoin a few diagrams, showing the layers as isolated from the pericarp; namely, fig. 9 parenchyma, a layer of sklerogenous cells, fig. 10, and the silver membrane (is) with two superjacent Mitscherlich particles (tr) in fig. 11.

Fig. 8.