Chapter IV: Front Matter (4)

Globulins combine with aqueous solutions of alkalis such as potash, soda, ammonia etc. producing alkaline albuminates; with acids they form acid albuminates or syntonins. Both have the property in common, that whilst they are insoluble in pure water, they readily dissolve in slightly acidulated or alkaline water, as well as in weak saline solutions, and are then no longer coagulable by boiling.

Albuminous bodies are converted first into albumoses (proteoses), and then into peptons by gastric and intestinal digestion or by hydrolytic decomposition with acids or alkalis, also by the action of steam under pressure of many atmospheres, as well as by putrefaction. Albumoses, with the exception of hetero-albumose, are soluble in water. Peptons dissolve entirely and in that condition are absorbed by the animal organism.

Albumins are precipitated from their solutions by strong alcohol, and in that way Zipperer succeeded in precipitating 4·25 percent of albumin from the aqueous extract of Trinidad cacao, which corresponds to about 25 percent of the total amount of albumen in the bean.

The results of his investigation have shown that generally more soluble albumen is present in the unfermented than in the fermented bean. Consequently, it would appear that in the finer kinds of cacao beans, in which very careful fermentation has been carried out, the albumin, owing to fermentative alteration, is rendered less soluble.

The constitution of albumin is still not sufficiently known, despite the excellent experiments of E. Fischer on this subject; generally it is regarded as having the formula:

C 52·31-54·33%
H 7·13- 7·73%
N 15·49-17·60%
S 0·76- 1·55%
O 20·55-22·98%

Accepting a mean formula corresponding to the above figures as representation of the albumen (namely C_{72}H_{112}N_{18}SO_{22}), it becomes possible to obtain a quantitative determination of this constituent in the plants in which it is contained. There is, for instance, 16 % of nitrogen here. Starting from such a standpoint, and determining the percentage of Nitrogen contained in a plant, and multiplying by 6·25 (i. e. 16 %), the amount of albumen is obtained. For further particulars see paragraph 4. The albumen in cacao, as previously mentioned, is in the form of globulin, that is, in a less soluble form. In cacao preparations which are required for invalids, especially those with affections of the stomach, it is important to have the albumen in a more readily soluble condition. Various attempts have been made with cacao preparations to obtain that result, and later on, full illustrations and explanations will be given on this subject. First of all, however, it is desirable to consider the scientific methods employed to ascertain the relative digestibility or indigestibility of albumen.

Professor Stutzer[69] of Bonn has been engaged in determining the action of digestive ferments of the animal organism on alimentary substances, and has worked out a method by which it is possible to ascertain the proportion of albuminous substances which can be regarded as digestible.

The method depends upon the fact that salivary, gastric and intestinal digestion can be artificially imitated in the laboratory. But as the salivary secretion only digests starch and is difficult to obtain, malt diastase, which serves the same purpose, is used instead. On the other hand albuminous material is only digested by juices of the stomach and intestines as fresh obtained from the mucous membranes of the pig or ox. If we suppose an average of 16 percent of total albumen in cocoa powder, the following results would probably be given by Stutzer’s method:

Of 16 % of total albumen there are on an average:

| corresponding to percentage
| of the total mass:
|
} 7·6% soluble in the stomach | 47·5% } 65%
} 2·8% soluble in the intestines | 17·5% }
Albumen: } 5·6% insoluble | 35·0%
} ——- | ———
} 16·0% | 100·0%

As shown by the experiments of Forster[70] however, artificial digestion does not correctly represent the actual consumption of nutriment in the human body. ~Forster’s~ experiments, in which cacao powder was administered to healthy men, gave a much higher value, in fact, 80 percent of the nitrogenous substance was digested, against 65 percent by Stutzer’s artificial method of digestion. The results obtained by artificial digestion must therefore be increased in that proportion.

6. ~Starch.~

Starch is one of the most important constituents of cacao, as on the starch taken in conjunction with the fat and albumen depends the nutritive value of the cacao bean. As previously stated, cacao starch is one of the smallest kinds which occur in the vegetable kingdom; consequently it can easily be distinguished from the starch granules of other plants. Owing to their minuteness the concentric rings showing the stratified structure of the starch granules can only be distinguished with difficulty under the microscope. Cacao starch consists usually of globular granules, generally separate, but sometimes in aggregations of two or three. The appearance under the microscope of the starch granules is clearly shown in fig 7, which represents a section of Ariba cacao enlarged 750 times.[71]

=a= on the above represents the intercellular spaces, =b= the cell walls, =c= the starch granules, =d= the fat crystals, those being the contents and structural elements of the cacao cell that the microscope will at once distinguish.

Cacao starch has the usual properties of ordinary kinds of starch, namely:

1. ~It is gelatinised by hot water~, that is to say, the water penetrates between the layers of starch granules, separating them and causing by its penetration a swelling up of the starch whereby a transparent mass know as “starch paste” is produced. It has been supposed that cacao starch is less easily gelatinised than the starch of other plants. According to investigations of Soltsien’s[72], which Zipperer unreservedly endorses, this is not the case, for under certain essential conditions, cacao starch gelatinises just as readily as other kinds of starch.

~The blue coloration of starch with iodine.~

This is said to take place more slowly with cacao than with other starches, though we have always found that once the cacao starch is gelatinised, a blue coloration appears immediately on adding a sufficiently strong solution of iodine.

There are certainly other materials in the cacao bean, such as fat, which by more or less enveloping the starch, prevent access of water to the starch granules and thus hinder gelatinisation; or again, the albumen and cacao-red may exert some retarding influence on the iodine reaction, ~especially if the iodine solution used is very dilute~. Yet it is impossible to describe the reaction as slow.

According to Soltsien, if a mixture of two parts of cacao bean with one part of calcinated magnesia and water is heated, a clear-filtering decoction is obtained, which immediately assumes the blue colour on addition of iodine solution. On neutralising the filtrate with acetic acid, and adding 3-4 parts of strong alcohol, its starch is precipitated.

~By boiling with dilute acids as well as by the action of ferments like the saliva, diastase~ etc., ~starch is converted into starch sugar~ (~glucose~, ~dextrose~). The empirical formula for starch is C_{6}H_{10}O_{5}, that for starch sugar is C_{6}H_{12}O_{6}, so that in the conversion one molecule of water is introduced, wherefore its chemical nature is greatly changed, and especially in its becoming freely soluble in water. That alteration allows of starch being quantitatively determined, as the dextrose thus produced has the property of reducing an alkaline solution of copper sulphate (known as Fehling’s solution, after the discoverer); that is to say, the copper sulphate is converted into insoluble red cuprous oxide. As dextrose always precipitates a definite amount of cuprous oxide, the quantity of starch present can in that way be determined.

The chemical determination of starch is only in a limited degree effectual in the recognition of an admixture of foreign starch in cacao preparations. If more than 10-15 percent of starch (calculated on the crude bean) has been found, then it must be assumed that there has been an admixture of foreign starch, but chemistry affords no means by which foreign starch can be distinguished from the genuine starch of the cacao bean. For that purpose the foreign starch must be minutely observed under the microscope, which not only serves to detect its presence, but gives an approximate estimation of the amount present, and its origin. Great caution should be exercised, or the result may be easily exaggerated.

7. ~Cellulose or crude fibre.~

We have already made the acquaintance of this material as the chief constituent of the cell walls and vascular tissues. Recent chemical investigations have shown that it consists of the anhydrides of hexose and pentose (sugar compounds) incrustated with many impurities, such as cacao-red, gum, mucilage etc. From a chemical point of view, cellulose has the same formula as starch, viz. C_{6}H_{10}O_{5}, or one of its multiples represented in formula. One of its chemical properties is solubility in ammonio-cupric sulphate, and affinity for alkalis such as potash, soda, ammonia, causes it to swell when they act on the cell fibres.

Weender’s process[73] as worked out by Henneberg is the one usually adopted for the determination of crude fibre in plants, although recently H. Suringar, B. Tollens[74] and more particular König[75] have pointed out that in Weender’s process the so-called pentosan, that is to say, the sugar-like constituent of the composition C_{5}H_{10}O_{5}, which comprises a not inconsiderable portion of the crude fibre, undergoes a disproportionate alteration, so that the analytical results thus obtained can by no means give an accurate representation of the amount of cellulose. The crude fibre must therefore be treated in such manner as to eliminate the pentosan. For this purpose the various methods of König, Matthes and Streitberger have been proposed, to which we shall return in Book 4. Filsinger, the meritorious experimenter on the subject of cacao, has by König’s method determined the amount of crude fibre in a series of different varieties of cacao bean, and obtained the following results as regards shelled and roasted beans.

percent
1. Puerto Cabello 5·37
2. Java 3·97
3. Ariba Guayaquil I 4·10
4. Ariba Guayaquil II 4·07
5. Machala Guayaquil I 4·43
6. Para 4·01
7. Surinam Guiana 3·01
8. Bahia 2·81
9. Grenada 3·10
10. Guatemala 3·50
11. Machala Guayaquil II 3·58
12. Caracas 3·65
13. Samana 4·58
14. St. Thomé A I 4·13
15. St. Thomé A II 2·95
16. St. Thomé B 3·15
17. Haiti 3·12[76]

These new values may be provisionally regarded as normal. From these results not only can an idea of the functioning of the cacao shelling machine be obtained, but also the presence of any occasional admixture of husk in cacao preparations may be inferred, since the husk contains a great deal more crude fibre than the kernel. Therefore the determination of the crude fibre is an important item in the testing of cacao preparations, as there is no doubt that the presence of vegetable substances rich in crude fibre can be detected by the increase in the amount of cellulose.

8. ~Sugar and plant acids.~

The presence of glucose in raw cacao beans was first pointed out by Schweitzer[77]. The sugar is formed by the action of the cacao ferment on the glucoside cacaonin during the processes of drying and fermentation. In addition to sugar, malic and tartaric acids have been observed. These substances, however, are only of interest to the plant physiologist and not to the manufacturer, so it is sufficient merely to notice them here in passing.

9. ~The mineral or ash constituents.~

When cacao beans are ignited, the constituents of an organic nature are volatilised and only the non-volatile or inorganic constituents remain behind. These consist of potash, soda, lime, iron magnesia, combined with silicic acid, phosphoric acid, sulphuric acid and chlorine.

The amount of ash in raw and shelled cacao beans varies from 3-4 %. Tuchen[78] found 2·9-3 %, Trojanowski[79] 2·08-3·93 %, Zipperer[80] 2·7-4 %, L’Hote[81] 2·2-4 %, H. Beckurts[82] 2·20-3·75, J. Hockauf[83] 2·84-4·4 percent. Of those kinds which are now most in use, Ceylon gave 3·30 percent, Java 3·20 and Kameroon 2·95 percent. (Beckurts).

Quantitative analyses of the ash of the cacao beans have been made by several investigators, and the following table gives a series of the most complete analyses, made by R. Bensemann[84].

~Table~ 14. =Analysis of the ash of Cacao Beans by R. Bensemann.=

The ash of the kernel free from husk dried at 100°C. contained:
————————————————————————+——————+——————+——————+——————+——————+——————-
Insoluble respectively |Mara- |Cara- |Trini-|Mach- |Porto | Mean
in dilute hydrochloric |caibo | cas | dad | ala | Cab- |
or nitric acid | | | | | ello |
————————————————————————+——————+——————+——————+——————+——————+——————-
a) Volatile dessicated | 0·142| 0·076| 0·144| 0·074| 0·198| 0·127
at 100° C. | | | | | |
b) Fixed at red heat | 0·312| 1·663| 0·553| 0·630| 1·075| 0·846
| | | | | |
Soluble in dilute | | | | | |
hydrochloric | | | | | |
or nitric acid: | | | | | |
c) Potassium oxide |35·889|33·844|30·845|30·686|29·989|32·251
K_{2}O | | | | | |
d) Sodium oxide | 0·515| 0·766| 1·964| 4·173| 3·427| 2·169
Na_{2}O | | | | | |
e) Calcium oxide CaO | 4·118| 5·030| 4·638| 3·112| 2·923| 3·964
f) Magnesium oxide MgO |15·750|15·151|16·060|16·172|17·562|16·139
g) Ferric oxide | 0·182| 0·217| 0·491| 0·629| 0·303| 0·364
Fe_{2}O_{3} | | | | | |
h) Aluminium oxide | 0·080| 0·326| 0·490| 0·432| 0·305| 0·327
Al_{2}O_{3} | | | | | |
i) Silicic acid | 0·214| 0·211| 0·169| 0·134| 0·240| 0·194
SiO_{2} | | | | | |
k) Phosphoric anhydride|27·741|29·302|28·624|37·000|35·274|31·588
P_{2}O_{5} | | | | | |
l) Sulphuric anhydride | 2·632| 2·740| 3·957| 2·042| 3·952| 3·065
SO_{3} | | | | | |
m) Chlorine Cl | 0·295| 0·341| 0·427| 0·279| 0·085| 0·285
n) Carbonic anhydride |10·349| 8·435| 8·953| 2·788| 3·481| 6·801
CO_{2} | | | | | |
o) Water H_{2}O | 1·847| 1·975| 2·781| 1·912| 1·205| 1·944
Oxygen O equivalent | 0·066| 0·077| 0·090| 0·063| 0·019| 0·064
to chlorine

In previously describing the aleuron granules of the cacao bean it was mentioned that they contain a comparatively large globoid. According to Molisch[85], when sections are cautiously heated on platinum foil, these globules are found in the ash. From their number they give a characteristic appearance to the ash of cacao beans, and thus may serve as a good means of identifying cacao, since they can be detected in the smallest quantity of a genuine cacao preparation.

A noteworthy fact may here be mentioned, namely the presence of a rather small amount of copper in the ash of cacao beans as well as the husks. Duclaux[86] was the first to point out this fact, which several other observers, such as Skalweit[87] and Galippe[88] have also confirmed. The amount of copper in the husk varies from 0·02 to 0·025 percent and in the beans from 0·0009-0·004 percent (Duclaux). Copper in similar amount is found in all kinds of beans and husks, and its presence is due to the absorption of copper by the plant from the soil, whence it gradually accumulates in the fruit.

b) The Cacao Shells.

Most of the constituents which exist in the cacao kernels are also to be found in the husks and the methods for isolating and determining them are the same in both cases. The composition of the husk, according to Laube and Aldendorff[89], is as follows:

~Table~ 15.

Key to Row 1:
Col 4A = Nitrogenous substance
Col 6B = Non nitrogenous extractive
———————————————+——————+—————+————-+————-+————-+————-+————-+—————
|Amount| | | | | | |
| of | | | | |Woody| |
|husk |Water| 4A | Fat | 6B |fibre| Ash | Sand
———————————————+——————+—————+————-+————-+————-+————-+————-+—————
| ~Per cent~
———————————————+——————+—————+————-+————-+————-+————-+————-+—————
Caracas | 20·09| 7·74|11·68| 5·99|35·29|12·79| 8·32|18·62
Guayaquil | — | 9·11|12·94|10·75|47·08|13·12| 6·79| 0·21
Trinidad | 14·04| 8·30|15·14| 4·23|46·05|18·00| 7·06| 0·92
Puerto Cabello | 14·92| 6·40|13·75| 4·38|47·12|14·83| 6·06| 7·46
Soconusco | 18·58| 6·48|19·12| 6·48|39·39|15·67| 8·15| 4·71
Mean | 16·33| 7·83|14·29| 6·38|45·79|14·69| 7·12| 5·90

~Zipperer’s analysis[90] of the unroasted husks gave the following results~:

~Table~ 16.

Key to Row 1 abbreviations:
Col 2 = Surinam = Surin
Col 3 = Caracas = Carac
Col 4 = Trinidad = Trini
Col 5 = Puerto Cabello = P Cab
Col 6 = Machala = Mach
Col 7 = Port au Prince = P a P

————————————————————-+————-+————-+————-+————-+————-+————-+————-+—————
|Surin|Carac|Trini|P Cab|Mach |P a P|Ariba|Mean
————————————————————-+————-+————-+————-+————-+————-+————-+————-+—————
| ~Per cent~
————————————————————-+————-+————-+————-+————-+————-+————-+————-+—————
Moisture |13·02|11·90|13·09|12·04| — | — | — |12·51
Fat | 4·17| 4·15| 4·74| 4·00| — | — | — | 4·23
Cacao tannic acid | | | | | | | |
soluble in 80% | | | | | | | |
alcohol | 5·10| 3·80| 4·87| 9·15| — | — | — | 4·58
Theobromine | 0·33| 0·30| 0·40| 0·32| — | — | — | 0·33
Ash | 7·31|16·73| 7·78| 8·99| — | — | — |10·20
Woody fibre |14·85|17·99|18·04|15·98| — | — | — |16·71
Nitrogen | — | 2·25| 2·13| — | — | — | — | 2·19
Proportion of husk | | | | | | | |
in the raw seeds |14·60|15·00|14·68|12·28|16·14|16·00|18·68|15·34

Roasted cacao husks contain according to G. Paris[91] the following constituents:

Moisture 12·57 percent, nitrogenous substance 14·69 percent, fat 3·3 percent, extractives 45·76 percent, crude fibre 16·33 percent and ash 7·35 percent.

50 grammes of the husks when boiled with 500 grammes of water give 25·08 percent extract, 20·68 % organic substance, 4·4 % ash, 0·21 % sugar (reducing substance), 0·79 % theobromine, 0·12 % percent acid, calculated as tartaric acid.

The following constituents have been found by R. Bensemann[92] in the ash of cacao husks:

~Table~ 17[93].

==========================+========+=======+=======+========+========
| Mara- | Cara- | Trini-|Machala | Porta
| caibo | cas | dad |Guayaquil| Plata
+————————+———————+———————+————————+————————
| ~Per cent~
==========================+========+=======+=======+========+========
Ash dried at 100° C. | | | | |
| | | | |
I. insoluble in dilute | | | | |
hydrochloric | | | | |
or nitric acid: | | | | |
a) Volatile dessicated at | 0·113 0·421 | 0·979 | 0·306 | 1·247
100° C. | | | | |
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 K_{2}O | 31·517 |11·812 |25·866 | 23·117 | 12·174
d) Sodium oxide Na_{2}O | 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 | 0·647 | 0·931 | 0·339 | 0·958 | 0·462
Fe_{2}O_{3} | | | | |
h) Aluminium oxide | ·281 | 1·554 | 0·710 | 1·854 | 1·046
Al_{2}O_{3} | | | | |
i) Silicic acid SiO_{2} | 1·180 | 7·975 | 2·416 | 4·321 | 6·780
k) Phosphoric anhydride | 9·068 | 7·630 | 4·703 | 7·288 | 7·242
P_{2}O_{5} | | | | |
l) Sulphuric anhydride | 3·041 | 1·478 | 3·398 | 1·741 | 2·012
SO_{3} | | | | |
m) Chlorine Cl | 1·005 | 0·220 | 1·022 | 0·255 | 0·444
n) Carbonic anhydride | 25·454 | 5·399 |16·290 | 11·834 | 4·247
CO_{2} | | | | |
o) Water H_{2}O | 2·135 | 2·499 | 2·263 | 1·171 | 1·662
p) Oxygen O equivalent | 0·226 | 0·049 | 0·290 | 0·057 | 0·100
to chlorine | | | | |

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 percent. 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.

For microscopical examination, the husk must first be defatted with petroleum or ordinary ether and then treated with dilute chloral hydrate (8: 5) to assist the definition of the forms. An approximate estimation of the amount of husk in a cacao preparation can be made by means of the microscope, adopting Filsinger’s[96] levigation method, which consists of concentrating those elements of the cacao which are seldom seen even in suspension in water, and which sink to the bottom when repeatedly stirred in that liquid. To these belongs first of all the husk, and its presence and determination in the levigation method is accordingly greatly facilitated. The details of the method will be further described in treating of husk admixtures in cacao preparations.

Cacao shells are the only by-product in the cacao industry, and have been developed and exploited to such an extent, that a rational utilisation of the ever increasing quantities has become a matter of urgent necessity. They are not used in our industry, for an admixture of husk is not permissible, even in the inferior kinds of chocolate or cocoa powder, but must be regarded as an adulteration. It is true that they have been brought on the market as cocoa tea, and again, have been coated with sugar, to make them tasty; and to this day, candied husks constitute a favourite sweetmeat of the population of East Germany. But in this way only comparatively inferior quantities of the by-product were absorbed, and consequently projects of all kinds have been suggested to use up larger percentage. As we have seen, the fatty contents of the bean can be extracted with benzine, and there is a resultant 4 or 5 percentage of fat of inferior value, which is commercially known as “Dutch IIa Cacao Butter”; the defatted shells can be further used for the preparation of theobromine, as Zipperer has already noted in the first edition of this book.

Kathreiner’s successors in Munich[97] employ an extract of cacao shells prepared with hot water, in order to improve coffee berries during the roasting and to give a flavour to the coffee substitutes prepared from corn and malt. Cacao extract is also prepared from the shells[98] by first treating them with water or steam, and afterwards extracting with water, and finally evaporating as far as necessary. The thick extract thus prepared contains theobromine, and is intended for use either alone or as an addition to cacao powder and chocolate.

Strohschein in Berlin[99] prepares from the shells a thick liquid extract which he calls “Martol Its preparation was suggested by the fact that the cacao husk gives evidence of containing a considerable amount of iron. In “Martol”, the iron occurs as a tannate, and the preparation further contains theobromine, carbohydrates, and phosphoric acid. The preparation is said to be used as a medicinal remedy in chlorosis, yet has scarcely justified such a statement.

Alfred Michel of Eilenberg[100] utilises the shells in the preparation of a brown colouring material. The husks, free from impurities, are first soaked in soft water, with or without the addition of sulphuric acid, then washed and finally treated with a strong 35 % solution of caustic soda. From the alkaline solution, the colouring matter is precipitated with acid or acid metallic salt, collected on a filter, and again washed. Thus obtained, it is a dark reddish-brown paste, possessed of a vitreous fracture. The yield of colouring matter is from 20-25 % of the weight of the original shells. By re-treatment with alkali, the paste can be again obtained in solution and can be used as required, either in liquid or paste form. The colouring matter can be obtained in different tints, either by soaking the shells in more er less dilute sulphuric acid, or by precipitation from the alkaline solution at various temperatures, or yet again, by the addition of metallic oxides.

Boussignault[101] says that in Paris briquettes have been made from cacao shells, and twenty-two years ago, Zipperer[102] proposed to use them as fodder, especially for horses. Experimental work in that direction was instituted, but for various reasons, had to be abandoned. The question as to a rational working up of the husk of the cacao bean is once more receiving special consideration, more particularly since the publication by the “Association of German Chocolate Manufacturers” of a prize essay on the subject. The fodder value of the husks as determined by Märcker is apparent from the following figures:

~Table~ 18.

===========================+=============+===========+===========
| free from | | whole and
Shells | dust, whole | fine meal | dusty
| % | % | %
===========================+=============+===========+===========
Moisture | 9·08 | 6·50 | 9·95
Albumen | 13·56 | 14·13 | 12·69
“ digestible | 6·06 | 7·07 | 4·38
Fat | 2·65 | 6·76 | 3·96
Raw fibre | 29·14 | 25·80 | 21·55
Ash | 6·32 | 6·44 | 7·26
Non-nitrogenous extractive | 39·25 | 40·37 | 44·59

Feeding experiments which were carried out in certain agricultural institutes showed that the cacao husk stands in nutritive value between good meadow hay and wheaten bran, and is not only a fattening fodder for oxen, but also a valuable feeding material for cows and deer[103]. These results have been confirmed by Prof. Feruccio Faelli in Turin[104].

The advantages of cacao shells as fodder, when a comparison with bran is established, are at once apparent. Two hundredweight (that is to say, about 220 lbs. averdupois) cost only from six to seven shillings, whilst the price of bran varies between nine and ten shillings. The husks also keep better, for after having been stored eighteen months, Professor Faelli found that they had undergone no alteration, whilst on the other hand bran had become sour. A further advantage possessed by the husk is that it will absorb four times its weight of water against three times absorbed by bran. Cattle not only readily get accustomed to the fodder but subsequently take to it with eagerness. The best results were obtained with Dutch, Swiss and Parmesan milch cows. After 10 days feeding the butter and milk-sugar had increased, as well as the daily average yield of milk from 44 to 49·5 kilogrammes. As soon as the feeding with cacao husk was discontinued the yield of milk decreased. Faelli concludes that cacao husk, which can be used as a fodder up to 4 kilog. daily, exercises a very favourable influence on milch cows, and he purposes to continue the investigation with horses.

In a report on the Experimental Farms of Canada 1898, page 151, reference is made to the manurial value of the husks in enriching the soil with nitrogen and potash, a fact which had already been pointed out by Boussignault.

The future use of the husks appears therefore to be ensured, and it is to be hoped that it will allow of a permanent consumption of this by-product.

FOOTNOTES:

[1] Of which the Central Province has 32,003 acres: North Western Province 3689 acres, North Central Province 25 acres, Province of Uva 2153 acres and Province of Sabaragamura 1918 acres. (From information kindly furnished in a letter of W. Freudenberg jun. German Consul at Colombo.)

[2] See references at the end of this book.

[3] Pronounced Chocolatl.

[4] Revue des sciences pures et appliquées 1899, No. 4, page 127.

[5] Vol. 7, Part 2: Diseases and Parasites of the Cacao Tree. With special reference to the conditions obtaining in the colonies belonging to Germany. By Dr. F. C. Faber, Berlin 1909, Parey & Springer.

[6] Recently so-called fermenting-houses, as recommended by L. Kindt. (Cf. Kultur d. Kakaobaues und seine Schädlinge, Hambourg 1904), have answered very well. Yet the chemismus of fermentation is by no means sufficiently explained, and quantitatively and qualitatively, there is a lack of completeness in the analyses bearing on the process.

[7] Special ovens (System Mayfarth) are also used, and sometimes complete heating and drying installations.

[8] This had already been noticed by J. Hinchley Hart; Cacao (Trinidad 1892). It is therefore scarcely conceivable that the “Germination” theory should have held the field so long.

[9] According to Schweizer (Pharmazeut. Ztg. 1898, page 389) these substances would be represented by the chemical formula C_{60}H_{86}O_{15}N_{4}, corresponding to 1 molecule cacao red, 6 molecules grape sugar, and 1 molecule Theobromin.

[10] Cf. Hilger, Apotheker-Ztg. 1892, p. 469.

[11] Cf. Tropenpflanzer V. 4, 1901, April-Number.

[12] Loc. cit. page 167.

[13] The leaves of the tobacco plant must also be fermented, before they acquire their rich brown colour and peculiar aroma.

[14] Reports of the German Pharmaceutical Society 1900, Vol. 5, page 115.

[15] J. F. Hanousek, Die Nahrungs-und Genußmittel aus dem Pflanzenreiche. p. 437.

[16] Anleitung zur mikroskopischen Untersuchung der Nahrungs-und Genußmittel. Jena 1886.

[17] Grundriß einer Histochemie der pflanzlichen Genussmittel.

[18] See page 16 loc. cit.

[19] Cf. Dr. Stollwerck. The Cacao and Chocolate Industries.

[20] Mitscherlich, p. 57.

[21] Cacao and its Preparation; a few Experiments.

[22] Ridenour, M. American Journal of Pharmacy, 1895. Vol. 67, p. 207.

[23] Filsinger, Chemical Journal, 1887, p. 202.

[24] Z. U. N. G., 1906. Vol. 12, p. 88 et seq.

[25] The husks contain no fat when in a fresh condition but absorb fat from the bean when the cacao is fermented and dried; especially so also in the later process of roasting, when they become saturated with it.

[26] Klimont, Ber. d. Dtsch. chem. Ges. 34, 2636; Monatssch. f. Chem. 1902 (23) 51; 1904 (25) 929; 1905 (26) 536.

[27] Journal of the Society of Chemical Industry 1899, p. 556.

[28] Chevalier & Baudrimont, Dictionnaire des alterations.

[29] Achiv de Pharmacie 1888, Vol. 26, p. 830.

[30] See previous reference.

[31] Schmidt, Ztschr. analyt. Chem. 1898, vol. 301 p. 301; cf. also P. Welmans, Pharm. Ztg. 1894, p. 776.

[32] Pharm. Zeitung 1898 No. 10.

[33] Cor. Assoc. Germ. Choc. Man. 1889, Vol. 5, p. 65.

[34] The Brit. and Colon. Druggist 1897 No. 21.

[35] Zeitschr. anal. Chemie.

[36] The Reichert-Meissl number (to be discussed later), according to a communication from P. Welmans, reaches 1 Burstyn in the expressed fat and amounts to 1·66 cc. in the extracted fat (no. of cc. of normal potash solution to 100 grammes of fat).

[37] Dingler, Polytechnical Journal, Vol. 253, p. 281. For details of the method compare also P. Welmans Zeitschrift für öffentl. Chemie, 1900, No. 5.

[38] Zeitschrift für anal. Chemie 1896, p. 519.

[39] Zeitschrift für öffentl. Chemie 1900, p. 95.

[40] Though Strohl Zeit. Analyt. Ch. 1896. Vol. 35. p. 166. has obtained with a Bahia fat an iodine value of 41·7, possibly exception due to some over-roasting of the beans or to their fat having been extracted by a petroleum ether of very high boiling point. Cf. also table 12.

[41] Zeitschr. Analyt. Chem. B. 21. p. 394.

[42] Correspondence of the Association of German Chocolate Manufacturers.

[43] Zeitschrift für angew. Chem. 1898, p. 116.

[44] We are indebted for this table to the kindness of Dr. Fritsche, Superintendent Meat Inspector at Cleves (Cf. also table of experiments of Matthes & Müller, loc. cit p.—et seq.).

[45] Benedikt-Ulzer, Analyse der Fett-und Wachsarten. 5th. edition. 1908. p. 840. also Literature.

[46] These high percentages of acid may also be caused by the high percentage of benzine used in the production.

[47] A. Ruffin, Pharmaceutische Rundschau 1899, No. 51, p. 820.

[48] Therapeutische Monatshefte. 1895. p. 345 and following pages.

[49] Compt. rendus de l’aced. des sciences de Paris, Vol. 123, p. 587.

[50] Apotheker-Zeitung 1892, p. 469 and Deutsche Vierteljahrsschrift für öffentl. Gesundheitspflege 1893, No. 3.

[51] Pharmaceut. Zeitung 1898, p. 389.

[52] Hilger and Lazarus, Compare also Schweitzer, Pharmaceut. Zeitg. 1898, p. 389.

[53] Ann. d. Chem. and Pharm. 1841, Vol. 41, p. 125.

[54] Ibid. Bd. 118, pag. 151.

[55] Berliner Chemische Berichte 1897, pag. 1839.

[56] Archiv f. experiment. Pathol. u. Pharmacol. 1895, Vol. 35, pag. 449.

[57] Ibid. 1896, Vol. 30, pag. 53.

[58] Ibid. 1896, Vol. 36, pag. 66.

[59] Ibid. 1888, Vol. 24, p. 101.

[60] Therapeut. Monatshefte 1890, p. 10.

[61] Semaine médicale 1893, p. 366.

[62] Pharmaceut. Centralhalle 1898, p. 901.

[63] Dekker (Swiss Weekly Journal, Chem. a. Pharm.) 40, p. 436, 441, 451 u. 463 gives the following figures at 15 ° C.: Water 1800 parts, spirits 1600, pure alcohol 3570, chloroform 3845, ether 25000, acetic unit 3845, benzol 100000 and amylic alcohol 1250.

[64] See before.

[65] Journal de Pharmacie et de Chimie 1898, p. 176.

[66] Ibidem 1897, p. 329.

[67] Zeitschrift für analytische Chemie, Vol. 18, p. 346.

[68] Aleuron granules were first microscopically observed by H. Molisch (Grundriß einer Histochemie d. pflanzl. Genßmittel in the cellular tissue of the cacao bean. They are very similar to the starch granules of the bean and contain within them a relatively large globoid lime and magnesium phosphates associated with an organic substance (sugar) which becomes visible in the form of globules when a section is incinerated.

[69] Zeitschrift für physiologische Chemie, Vol. 11, p. 207-232.

[70] Hygienische Rundschau. 1900. p. 314 & 315.

[71] E. S. Bastin, American Journal of Pharmacy 1894, p. 369.

[72] Chemischer technischer Centralanzeiger 1886, No. 53, p. 777.

[73] Contributions to the establishment of a rational feeding of ruminants. So-called Weender’sche Beiträge, 1864 Number, p. 48 and also Landwirtsch. Versuchsstationen, Vol. 6, p. 497.

[74] Zeitschrift für angewandte Chemie 1896, p. 712 und 749.

[75] Zeitschrift für Untersuchung von Nahrungs-und Genußmittel. 1898. p. 3.

[76] Zeitschrift für öffentliche Chemie 1900, p. 223.

[77] Pharmaceutische Zeitung 1898, p. 390.

[78] Archiv der Pharmacie 1860, Vol. 153, p. 59.

[79] Beitrag zur pharmak. und chem. Kenntnis des Cacaos. Inaug.-Dissertation Dorpat 1875.

[80] Untersuchungen über Kakao und dessen Präparate, 1887.

[81] Jahresbericht über die Fortschritte der Pharmacognosie etc. 1883, p. 314.

[82] Archive der Pharmacie 1893, Vol. 231, p. 694.

[83] Zeitschrift des allgem. öster. Apoth.-Vereins 1898, p. 434.

[84] Repert. f. anal. Chemie 1885, Vol. 5, p. 178; cf. also the investigations of Mathes & Müller.

[85] Grundriß einer Histochemie der pflanzl. Genußmittel, p. 22.

[86] Bulletin de la société chimique Paris 1872, p. 33.

[87] Pharmaceut. Zeitung Vol. 24, p. 243.

[88] Journ. de Pharm. et de Chim. 1883, Ser. V, Vol. 7, p. 506.

[89] König, Die menschlichen Nahrungs-und Genußmittel, Vol. 1, p. 261.

[90] Zipperer, Untersuchungen über Cacao und dessen Präparate, p. 55.

[91] Zeitschr. für Untersuchung von Nahrungs-u. Genußmitteln 1898, No.

[92] Repertorium der analyt. Chemie 1885, Vol. 5, p. 178.

[93] Compare Matthes & Müller, Z. U. N. 1906, Vol. 12, p. 90 et seq.

[94] Almost a tenth part of the ash of the shells consists of silica.

[95] cf. Moeller Mikroskopie der Nahrungs-und Genußmittel. Berlin. 1905. II part Springer p. 412.

[96] Ztschr. öffentl. Ch. 1899, p. 27.

[97] German patent No. 71, 373, 8th. January 1873.

[98] Engl. Patent No. 14624, June 16th. 1897.

[99] Pharm. Rundschau 1898, p. 781.

[100] Ztschr. für chemische Industrie 1878, p. 303, German Patent No. 2112, Sept. 24th. 1878.

[101] Annales de Chimie et de Physique, Vol. 183, p. 423.

[102] Zeitschrift für Pferdekunde und Pferdezucht 1888, No. 7. Nowadays cacao shells are often added to fodder.

[103] Quoted by Filsinger Zeitschr. f. öffentl. Chemie 1899, p. 27.

[104] Communication from the Assoc. German Choc. Manufacturers, 19th. year, No. 7.

+Part II.+

The Manufacture of Cacao Preparations.

A. Manufacture of Chocolate.

The Preparation of the Cacao Beans.

Up to the end of the eighteenth century the manufacture of chocolate was carried on entirely by hand, a method at once laborious and inefficient. The workman used to kneel down on the ground, and crush the beans in iron mortars. It was not until 1732[105] that Buisson introduced the use of a bench and so rendered that inconvenient and unwholesome practice unnecessary. Even to-day, the Chinese cooks on the Philippine islands carry their chocolate “Factory” about with them, in which the trestle is essential. It further comprises a small marble mortar and warmed pestle, and by means of these utensils and implements the hulled beans are pounded, and the triturated mass so obtained spread out. It is then flavoured with sugar and spices. With that exception, hand labour in the chocolate manufacture has since the year 1778 been entirely displaced by machinery, when Doret exhibited the first specimen before the medical faculty of Paris. According to Belfort de la Roque,[106] a Genoese named Bozelly had already constructed a mill by means of which he was able to prepare from six to seven hundred pounds of chocolate daily, comparing favourably with the thirty pound output yielded by hand labour. Pelletier[107], in 1819, describes a machine for the mechanical preparation of chocolate of his own construction, capable of doing the work of seven men. The machines used in the chocolate manufacture have since that time been repeatedly improved and re-constructed, although always with this one end in view, namely to obtain a fine even cacao mass, and afterwards mix it as thoroughly as possible with the other ingredients employed.

The first machines of the modern type were constructed by the Parisian mechanic George Hermann (1801-1883) in the year 1830, to which inventor we are indebted for the principle of fine grinding with varying velocities, on which manufacture of chocolate is based to-day. There is at the present time a rather large circle of manufacturers engaged in the putting together of special machines for the preparation of cacao and cacao products, chocolate apart.

Whether chocolate manufacture be carried out on a large or small scale, it always involves the subjecting of the cacao bean to a regularly succeeding series of operations, before the resulting product known as “Chocolate” (in the strict commercial sense of the term) can be obtained.

The respective operations succeed each other as follows:

I. ~Preparation of the Beans.~

1. ~Storing~, ~cleansing~ and ~sorting~ of raw beans.

2. ~Roasting~ the cleansed beans.

3. ~Crushing~, ~shelling~ and ~cleansing~ the roasted bean (removing the radicles etc.)

4. ~Mixing~ different kinds of beans.

II. ~Production of the Cacao Mass.~

5. ~Grinding~ the beans till they yield a homogenous paste on heating.

6. ~Mixture~ of the liquefied cacao mass with sugar, spices, etc.

7. ~Trituration~ by rollers.

III. ~Preparation~ of the resulting ~Chocolate~.

8. ~Extraction~ of ~air~, ~division~ and ~moulding~.

9. ~Cooling.~

10. ~Packing~ and ~storing~.

This represents the general course of manufacture, which we will now proceed to describe in more detail, following the headings given above.

1. Preparation of the Beans.

1. ~Storing~, ~cleansing~ and ~sorting~.

Right up to the moment when they are to be used in the manufacture, the raw cacao beans must be kept as originally packed, and stored in an airy sun-lit room; although if they have accumulated moisture during transport or sustained any manner of damage in harvesting, they should then be emptied out of the sacks, spread out over the floor of such a room as above described, and dried as effectively as possible. It has also been recommended that such beans be washed with a dilute solution of caustic potash (1 in 5000), and afterwards dried rapidly.

Unfermented beans, those damaged in the harvest, and those which have received no proper fermentation, develop a greyish white colour with occasional tints of violet and an unpleasant, bitter herbal flavour, properties which unfortunately penetrate to the resulting cacao products. Attempts have been made to meet this evil with a so-called “Secondary Fermenting Gordian[108] proposes in this connection that the beans be filled in water-butts, and steeped in warm water for at least 48 hours (so that obviously the butts must be kept in a warm room), at the expiration of which time it can be poured off, and the beans dried in a chamber heated to a temperature of between forty and fifty degrees centigrade. There is said to ensue an appreciable improvement as to flavour and colour, when this process is carried out.

The magazines in which cacao beans are stored have sometimes an unwelcome visitor, to wit, a grub which according to W. Hauswaldt[109] happens to attack just the best kinds of Caracas and Trinidad. As eggs of the grub have on several occasions been found on the interior of the still unshelled bean, we may assume that they were deposited by a butterfly (species unknown, but possibly Ephestia cahiriteller, cf. von Faber loc. cit. page 335) either before or immediately after fermentation, and no later. Sometimes these grubs appear on the surface of the sacks, which they overspread in a few days. Removal of the infected packages, opening the sacks, and exposure to the sun, as well as a thorough cleansing of the storehouses, is attended with a qualified amount of success. The best plan is to destroy the moths during their period of activity in the summer months June, July, and August.

According to Hauswaldt, Stollwerck[110] and G. Reinhardt[111], this can be effected by placing in the store rooms large, shallow basins of water, near which burning petroleum lamps are introduced on the approach of dusk, favourably placed on a pile of bricks and stone, so that they clearly illuminate the reflecting water. The moths assemble round the light en masse and either perish in the water or flame, a fate which sometimes overtakes even the larvae, for they display the same fatal attraction for any light, real or apparent. The water must be changed every day, as otherwise the wing-dust collecting on its surface affords a means of escape to the insects coming later. As the weather becomes cooler, the doors and windows of the store-rooms should be left open, so that when frost sets in, the rest of the maggots may be destroyed.

The cleansing and sorting of the raw cacao bean is the most important factor in the manufacture of chocolate, and yield a manifold return, for inferior and cheaper kinds of bean which have passed through these processes can be advantageously mixed with finer varieties. The chief object of cleansing and sorting is the removal of foreign bodies and such chance admixtures as sand, pebbles, and fragments of sacking, which are liable to damage the stones used in grinding at a later stage of the preparation, or communicate an unnatural and disagreeable smell to the subsequent roast products. These admixtures are so multiform and various that they cannot be removed solely by the aid of machinery, but must be finally picked out by hand. Mechanical appliances are limited to the removal of pebbles, dust, and possible fragments of iron, after which preliminary cleaning the beans are thrown on straps, where they can be picked by hand. The collector of these foreign bodies would find himself with a rather interesting stock at the end of a few years, as Wilhelm Schütte-Felsche points out.

The cleansing of the raw beans was formerly carried out in so-called roller casks, placed horizontally, and revolving round an axle fitted in the floor, whence it passed upward, cutting them slantwise. In this apparatus the beans were rolled and vigorously rubbed together, and afterwards the hand-picking succeeded. More recently, the roller casks have been displaced by rotary cylindrical sieves, driven by motor power.

Such a machine is illustrated in fig. 12. The beans are lifted to a rotatory cylindrical sieve by means of an elevator, where they are freed from dust and dirt; in other sections of the sieve fragments of blossom, sacking, or cloth are isolated, whilst occasional splinters of iron are removed by a large magnet. So prepared, the beans are cast on running belts, and here the hand-picking above-mentioned is carried out.

Fig. 13 shows a cleansing machine for the same purpose, which has recently become rather popular. Here the dust passing from the sieve is sucked up into a dust chamber, by means of an exhauster, whilst pebbles, blossom fragments, and small beans are separately isolated. The cleansed beans pass likewise under magnetic influence, which removes traces of iron, and finally succeed to the running belting.

Often the beans are introduced into an extensive brushing machine before roasting, to cleanse them from dirt etc. These are generally found in such factories as have circular and cylinder roasters with direct heating apparatus. Fig. 13 a shows such a brushing machine for cacao beans.

2. ~Roasting the Beans.~

The cleansed and sorted beans are now subjected to a high temperature, that is to say, they are now roasted. This roasting answers many purposes;

1. The aroma and flavour of the bean is so developed.

2. The starch granules are gelatinised.

3. The herbal constituents are so transformed that the flavour of the beans becomes milder; a distinct improvement.

4. In the consequent drying, the shells are rendered brittle, and more easily removeable.

5. The beans themselves can afterwards be better ground.

The roasting of the cacao bean does not demand so high a temperature as that of coffee, to effect the above chemical and physical changes. Experience has shown that the best temperature lies between 130-140 ° C., though deviations from this standard have recently become frequent and considerable, according to the uses for which the cacaos are intended, and roasting has sometimes taken place at a temperature even as low as 100 ° C.

The process of roasting can be carried out in the roasting drum or machine in a variety of ways, as:

1. Direct roasting over a coal fire,

2. Passing of a hot-air stream over the beans,

3. Roasting by means of gas, with compressed air, as far as ~sources of heat~ are concerned; and as regards ~shape of the drum~, it is to be noted that the cylindrical are most in use. The separation of the shells from the kernel was still effected at the beginning of the present century by stirring the beans in water and so detaching the inner coating of the seeds, the method adopted by Weisched (Mitscherlich page 112). Not till this stage had been reached were they subjected to a strong heat, causing the shells to spring off.

This method has at the present time only historical interest, for the so-called roasting drums, as used in the preparation of coffee, are now universal.

Roasting must be attended with the greatest care, in order that it may neither be too thorough nor insufficient. It is a great mistake to think that the roasting machine can be handed over to the care of any apprentice. That nicety of roasting which corresponds to the variety and its subsequent utilisation constitutes the qualitative basis of the chocolate manufactured later. It is impossible for even the best chocolate maker to retrieve what has been spoilt in this important preliminary operation, wherefore a skilled workman, endowed with a keen sense of taste and smell, is always to be seen at the roasting machine.

It has already been attempted to provide a means of security against over-burning by the construction of the so-called safety-roaster, about which will be spoken later.

Overroasting is immediately indicated by a disagreeable empyreumatic odour (resembling that of roasted coffee); the husks char and the kernels crumble, also betraying a charring on the outside. There is a correspondingly increasing keenness of flavour, and a transference of theobromine from the kernel to the husks (cf. page 65). From the destructive distillation of the cacao fat arises that volatile and pungent acroleine which is the principal cause of the empyreuma of the over-roasted bean.

The following general precautions in roasting cacao are worthy of note; 1. the beans should not remain too long in the roasting drum; 2. they should be kept on the stir, for which reason the apparatus is made revolvable on its axles; 3. the heat applied should be carefully regulated; and 4. to guard against a loss of aroma, the roasted beans should be cooled as rapidly as possible.

As the cacao must be more or less roasted according to its quality and ultimate destination, which entails the acquisition of considerable empirical knowledge on the part of the workman entrusted with this process, it would be neither advisable nor practicable to annex definite instructions as to time and temperature requirements.

In the following we describe a machine which is to be found in most factories and which corresponds to all the demands of technique. From its heating system, it belongs to the class of hot-air current roasters—direct coal fire assisting—and in shape to the cylindrical roasters.