Just as the beans of the cacao fruit are included under the botanical concept “Seed”, so also their chemical constituents closely resemble those common to every other seed. There are the usual reserve stuffs inherited from the mother plant, which serve as sustenance for the yet undeveloped organs, and compare with albumen in the feathered world. Apart from the constituents incidental to all plant life at this stage, such as albumin, starch, water, fat, sugar, cellulose and mineral stuffs such as ash, the cacao seed has two other components peculiar to itself;TheobromineandCacao-red. We adjoin a succession of chemical determinations respecting the quantitative proportions of these substances in the seed, and think further that we may be allowed to cite the results of fore-time investigators in this sphere, especially as their work has formed the basis for all future operations, and again, in view of the doubt which still prevails in scientific circles as to the “Normal” composition of the cacao bean.
Table4.Percentage Composition of the Hulled Bean.
AnalystPayen20Lampadius20Mitscherlich20Constituents percentUndescribedWest IndiesGuayaquilCaracas1. Water10·03·405·60—2. Nitrogenous matter20·016·7014·39—3. Theobromine2·2—1·20—4. Fat52·053·1045-4946-495. Cacao-red—2·073·50—6. Sugar——0·60—7. Gum and Starch10·07·7514·3013·58. Woody fibre2·00·905·80—9. Ash4·03·433·50—
Table5.
LaubeAldendorffConstituents percentCaracasGuayaquilTrinidadPuerto CabelloSurinam1. Water4·043·632·812·963·762. Nitrogenous matter14·6814·6815·0615·0311·003. Fat46·1849·0448·3250·5754·404. Starch12·7411·5614·9112·94—5. Other non-nitrogenous matter18·5012·6412·0611·4928·326. Woody fibre4·204·133·623·07—7. Ash3·863·723·223·942·35C. HeischConstituents percentGranadaBahiaCubaPara1. Water3·904·403·723·962. Nitrogenous matter12·457·318·5612·503. Fat45·6050·3045·3054·304. Starch————5. Other non-nitrogenous matter35·7035·3039·4126·336. Woody fibre————7. Ash2·402·605·903·06
The analyses carried out by Zipperer in the year 1886 yielded the following results21:
Table6.A) Analysis of the Raw Shelled Bean (Kernel).
Constituents percentNames of SortsAribaMachala GuayaquilCaracasPuerto Cabello1. Moisture8·356·336·508·402. Fat50·3952·6850·3153·013. Cacaotannic acid, sugar, decomposition products, phlobaphene8·9113·7210·767·854. Theobromine0·350·330·770·545. Starch5·788·297·6510·056. Cellulose and proteins22·1014·4519·8415·83ProteinsProteinsProteinsProteinstotototocellulosecellulosecellulosecellulose7. In the ratio7·3:15:16·6:15·3:18. Ash5·124·174·174·32SurinamTrinidadPort au PrinceAverage1. Moisture7·076·206·947·112. Fat50·8651·5753·6651·783. Cacaotannic acid, sugar, decomposition products, phlobaphene8·319·4611·3910·024. Theobromine0·500·400·320·455. Starch6·4111·078·968·336. Cellulose and proteins24·1318·4315·8118·71ProteinsProteinsProteinsProteinstotototocellulosecellulosecellulosecellulose7. In the ratio8:16:15·25:16·2:18. Ash2·722·872·923·60
In addition to these, there is an exhaustive succession of analyses conducted by Ridenour,22which we accordingly submit as Table 8. Following Filsinger,23we cannot regard these analyses asan absolutely trustworthy representation of the “Normal” composition of the cacao bean, the values in starch, albumin and ash considerably deviating from all that have been established up to the present time. Among more recent researches, we cite those carried out by Matthes and Fritz Müller.24
Table7.B) Analysis of the Raw Shelled Bean (Kernel).
Constituents percentNames of SortsAribaMachala GuayaquilCaracasPuerto Cabello1. Moisture8 ·526 ·257 ·486 ·582. Fat50·0752·0949·2448·403. Cacaotannic acid, sugar and phlobaphene8 ·617 ·846 ·858 ·254. Theobromine0 ·300 ·310 ·050 ·525. Starch9 ·1011·599 ·8510·966. Cellulose and protein bodies19·4318·1722·1621·21ProteinsProteinsProteinsProteinstotototocellulosecellulosecellulosecellulose7. In the ratio6·5:16:17·7:17:18. Ash3 ·893 ·753 ·924 ·08SurinamTrinidadPort au PrinceAverage1. Moisture4 ·047 ·856 ·276 ·712. Fat49·8848·1446·9049·243. Cacaotannic acid, sugar and phlobaphene8 ·087 ·697 ·197 ·784. Theobromine0 ·540 ·420 ·360 ·435. Starch10·198 ·7212·6410·436. Cellulose and protein bodies24·3923·0621·8221·43ProteinsProteinsProteinsProteinstotototocellulosecellulosecellulosecellulose7. In the ratio8:17·6:17·3:17·1:18. Ash2 ·884 ·124 ·823 ·92
Table8.Ridenour.
Commercial VarietiesConstituents percentBahiaSurinamJavaTrinidadRoastedTrinidadAribaCaracas1. Fat42·1041·0345·5043·6641·8943·3136·812. Theobromine1·080·931·160·850·930·861·133. Albumin7·5010·549·2511·9012·0210·1410·594. Glucose1·071·271·231·381·480·422·765. Saccharose0·510·350·510·320·281·581·566. Starch7·533·615·174·985·706·373·817. Lignin7·863·906·105·655·874·623·288. Cellulose13·8016·2413·8513·0119·6414·0716·359. Extractive by difference8·9913·538·908·315·849·0012·7210. Moisture5·965·555·126·342·635·906·6311. Ash3·603·053·313·603·708·734·36Commercial VarietiesConstituents percentRoastedCaracasGranadaTabascoMachalaMaracaiboAverage1. Fat37·6344·1150·9546·8442·2042·992. Theobromine0·990·751·150·761·030·973. Albumin12·369·767·8512·6911·5610·514. Glucose1·761·810·941·601·091·465. Saccharose0·510·552·720·461·360·896. Starch6·076·273·511·351·694·677. Lignin9·055·556·445·957·165·958. Cellulose11·6913·4912·5711·3217·3214·449. Extractive by difference9·229·729·269·026·799·3010. Moisture5·695·281·555·865·675·1811. Ash5·032·713·065·154·133·70
Table9.
No.DescriptionMoistureEtherNon-fattydry substancesMineralconstituentsIn waterinsoluble ashsoluble ash%%%%%%1St. Thomas II2·8255·87—2·791·930·862Java I2·7853·88—3·601·602·003St. Thomas I2·8254·50—3·011·851·164Caracas I2·6753·78—3·352·121·235Puerto Cabello3·3453·29—3·581·731·856Machala2·9353·98—3·342·101·247Samana2·9455·28—3·101·851·258Accra2·9453·94—3·191·841·35B. Percentages for the non-fatty dry substances.1St. Thomas II——41·366·5364·6721·8642Java I——43·348·3063·6924·6143St. Thomas I——42·687·0534·3112·7424Caracas I——43·557·6924·8682·8245Puerto Cabello——43·378·2543·9894·2656Machala——43·097·7674·9002·8677Samana——42·787·2464·3252·9218Accra——43·127·3984·2673·131C. Percentages for the total of ash.1St. Thomas II————71·4928·512Java I————44·4555·553St. Thomas I————61·1238·884Caracas I————63·3836·625Puerto Cabello————48·3351·676Machala————63·0936·917Samana————59·6940·318Accra————57·6842·32
No.DescriptionAlkali strengthPotassium Carbonatereckoned from Alkalistrength of soluble ashPure ash(mineral stuffsminus Pot. Carb.)of the soluble ashof the insoluble ashcb. mm. Nitric acid.%%1St. Thomas II3·64·80·252·542Java I10·46·80·722·883St. Thomas I2·65·00·181·834Caracas I4·64·80·323·035Puerto Cabello10·43·80·722·866Machala2·65·60·183·167Samana4·66·20·322·788Accra3·64·80·252·94B. Percentages for the non-fatty dry substances.1St. Thomas II8·711·60·605·942Java I24·015·71·666·653St. Thomas I6·111·70·426·634Caracas I10·611·00·736·965Puerto Cabello24·08·81·666·596Machala6·113·00·427·357Samana10·814·50·746·508Accra8·311·10·586·82C. Percentages for the total of ash.1St. Thomas II133·1177·49·1890·822Java I289·1189·120·0080·013St. Thomas I87·0167·06·0094·044Caracas I137·9143·99·5090·515Puerto Cabello290·7106·620·1079·896Machala78·5—5·4094·597Samana149·0200·010·2089·798Accra112·2150·07·892·16
No.DescriptionPhosphoric acidSilicic acid (SiO2)Ferric acid (Fe2O3)totalsoluble in waterinsoluble in water%%%%%1St. Thomas II1·02430·24740·77690·01540·04162Java I1·07530·46670·60860·03000·02243St. Thomas I1·11360·36210·75150·01220·04644Caracas I1·27080·33920·93160·00800·01845Puerto Cabello1·14330·46920·67410·02600·02076Machala1·28360·36470·91890·01160·02007Samana1·08810·32130·76680·00900·05608Accra1·12210·36720·35490·00820·0284B. Percentages for the non-fatty dry substances.1St. Thomas II2·47950·59891·88060·03730·10072Java I2·47901·07691·40210·06920·05173St. Thomas I2·60920·84841·76080·02860·10874Caracas I2·91800·77892·13560·01840·04225Puerto Cabello2·63611·08191·55420·06000·04776Machala2·98370·84812·13560·02690·04647Samana2·54350·75111·79340·02140·13098Accra2·60230·85161·75070·01910·0658C. Percentages for the total of ash.1St. Thomas II37·949·1628·780·5711·5412Java I29·8712·9616·910·8330·6233St. Thomas I37·2712·1225·150·4081·5514Caracas I37·9410·1227·820·2400·5495Puerto Cabello31·9413·1118·830·7270·5786Machala38·4210·9227·500·3460·5977Samana35·1210·3724·750·2951·8068Accra35·1811·5123·670·2580·889
Table10.Commoner Varieties.
Key to Column HeadingsC; MoistureD; Ether extractE; Mineral matterF; Potassium Carbonate reckoned on alkali soluble in waterG; Pure ash (mineral matter minus K2CO3)Ha; according to König, as modified by usHb; as yielded by the Wender processI; Silicic acid (SiO2)J; Ferric oxide (Fe2O3)K; Soluble in alcohol P2O5No.DescriptionCDEFG%%%%%1Superior Ariba, Summer crop6·9526·177·452·075·382Machala 81%,Thomé I 19%5·9428·797·061·995·073Machala 53%,Thomé I 47%6·4725·737·152·145·014Cameroon6·3626·417·052·334·725Thomé I 73%,Samana 27%7·9724·906·892·294·606Thomé II 60%,Samana 20%,Accra 20%7·3722·857·392·245·157Accra 60%,Thomé II 40%6·9322·807·362·255·118A}Same variety,6·5618·967·612·145·479B}more defatted6·0624·757·162·015·1510C}less defatted5·5829·726·571·894·6811Monarch double Ariba(R. & Cie.)7·5914·808·322·326·0012Helios(R. & Cie.)7·3717·257·912·125·79aAriba shells (R. & Cie.) very fine ground7·1714·007·402·205·20bgerms, Ariba (R. & Cie.) very fine ground6·6418·026·932·434·50No.DescriptionRaw FiberHaHbIJK%%%%%1Superior Ariba, Summer crop4·204·600·01700·05220·06052Machala 81%,Thomé I 19%5·005·470·01720·03730·06253Machala 53%,Thomé I 47%5·205·420·01860·05130·06124Cameroon4·634·640·0160—0·06695Thomé I 73%, Samana 27%4·204·380·01670·07530·06906Thomé II 60%,Samana 20%,Accra 20%4·235·000·02080·06780·07267Accra 60%,Thomé II 40%4·064·400·01980·05450·07668A}Same variety,4·005·240·0390——9B} more defatted3·584·61———10C} less defatted3·204·42———11Monarch double Ariba(R. & Cie.)6·90—0·0420—0·087712Helios(R. & Cie.)6·40—0·03400·04000·0930aAriba shells (R. & Cie.) very fine ground7·49—0·2976—0·0383bgerms, Ariba (R. & Cie.) very fine ground7·42———0·0587
Key to Column Headings
No.DescriptionCDEFG%%%%%1Superior Ariba, Summer crop6·9526·177·452·075·382Machala 81%,Thomé I 19%5·9428·797·061·995·073Machala 53%,Thomé I 47%6·4725·737·152·145·014Cameroon6·3626·417·052·334·725Thomé I 73%,Samana 27%7·9724·906·892·294·606Thomé II 60%,Samana 20%,Accra 20%7·3722·857·392·245·157Accra 60%,Thomé II 40%6·9322·807·362·255·118A}Same variety,6·5618·967·612·145·479B}more defatted6·0624·757·162·015·1510C}less defatted5·5829·726·571·894·6811Monarch double Ariba(R. & Cie.)7·5914·808·322·326·0012Helios(R. & Cie.)7·3717·257·912·125·79aAriba shells (R. & Cie.) very fine ground7·1714·007·402·205·20bgerms, Ariba (R. & Cie.) very fine ground6·6418·026·932·434·50No.DescriptionRaw FiberHaHbIJK%%%%%1Superior Ariba, Summer crop4·204·600·01700·05220·06052Machala 81%,Thomé I 19%5·005·470·01720·03730·06253Machala 53%,Thomé I 47%5·205·420·01860·05130·06124Cameroon4·634·640·0160—0·06695Thomé I 73%, Samana 27%4·204·380·01670·07530·06906Thomé II 60%,Samana 20%,Accra 20%4·235·000·02080·06780·07267Accra 60%,Thomé II 40%4·064·400·01980·05450·07668A}Same variety,4·005·240·0390——9B} more defatted3·584·61———10C} less defatted3·204·42———11Monarch double Ariba(R. & Cie.)6·90—0·0420—0·087712Helios(R. & Cie.)6·40—0·03400·04000·0930aAriba shells (R. & Cie.) very fine ground7·49—0·2976—0·0383bgerms, Ariba (R. & Cie.) very fine ground7·42———0·0587
Table11.Analysis of Cacao.Dry product, defatted and free from alkali.
Key to Column HeadingsC; Defatted and alkali-free dry productsD; Pure ash (mineral substances less K2CO3)E; Ash insoluble in waterF; Alkalinity of the insoluble ash Nitric acidGa; totalGb; soluble in waterGc; insoluble in waterH; Silicic acid (SiO2)I; Ferric oxide (Fe2O3)J; P3O5soluble in alcoholK; after König (modified)L; as yielded by the Weender processNo.DescriptionCDEF%%%ccm1Thomé II41·066·1864·72511·72Java I42·626·7573·75415·93Thomé I42·506·6594·35311·84Caracas I43·237·0104·90411·15Puerto-Cabello42·656·7064·0568·96Machala42·917·3654·89413·17Samana42·466·5484·35714·68Accra42·876·8584·29211·29Ariba64·818·301——10Machala +Thomé I63·288·013——11Thomé +Machala66·667·517——12Cameroon64·907·273——13Thomé I +Samana64·847·095——14Thomé II,Samana +Accra.67·547·625——15Accra +Thomé II68·027·513——16A72·347·561——17B67·187·666——18C62·807·452——19Monarch Ariba (R. & Cie.)75·297·969——20Helios Ariba (R. & Cie.)73·398·880——aShells76·636·786——bGerms72·916·173——No.DescriptionPhosphoric Acid (P205)GaGbGcHI%%%%%1Thomé II2·49470·60251·89220·03750·10132Java I2·52291·09501·42790·07040·05253Thomé I2·62020·85201·76820·02870·10914Caracas I2·93910·78461·15450·01850·04255Puerto-Cabello2·68071·10011·58060·06100·04806Machala2·99140·84992·14140·02700·04667Samana2·56260·78021·78240·02120·13198Accra2·61750·85651·76100·01910·0662Raw fibreJKL9Ariba0·09336·487·100·02620·080610Machala +Thomé I0·09847·908·640·02720·059011Thomé +Machala0·09197·808·130·02800·077012Cameroon0·10307·137·150·0246—13Thomé I +Samana0·10646·486·750·02580·116214Thomé II,Samana +Accra.0·10756·277·400·03080·100415Accra +Thomé II0·11265·976·470·02900·080116A—5·537·24——17B—5·336·87——18C—5·107·04——19Monarch Ariba (R. & Cie.)0·11659·16—0·0558—20Helios Ariba (R. & Cie.)0·12668·72—0·0446—aShells0·04999·77—0·38840·0545bGerms0·080510·18———1) See Table 9 A and Table 10.
Key to Column Headings
No.DescriptionCDEF%%%ccm1Thomé II41·066·1864·72511·72Java I42·626·7573·75415·93Thomé I42·506·6594·35311·84Caracas I43·237·0104·90411·15Puerto-Cabello42·656·7064·0568·96Machala42·917·3654·89413·17Samana42·466·5484·35714·68Accra42·876·8584·29211·29Ariba64·818·301——10Machala +Thomé I63·288·013——11Thomé +Machala66·667·517——12Cameroon64·907·273——13Thomé I +Samana64·847·095——14Thomé II,Samana +Accra.67·547·625——15Accra +Thomé II68·027·513——16A72·347·561——17B67·187·666——18C62·807·452——19Monarch Ariba (R. & Cie.)75·297·969——20Helios Ariba (R. & Cie.)73·398·880——aShells76·636·786——bGerms72·916·173——No.DescriptionPhosphoric Acid (P205)GaGbGcHI%%%%%1Thomé II2·49470·60251·89220·03750·10132Java I2·52291·09501·42790·07040·05253Thomé I2·62020·85201·76820·02870·10914Caracas I2·93910·78461·15450·01850·04255Puerto-Cabello2·68071·10011·58060·06100·04806Machala2·99140·84992·14140·02700·04667Samana2·56260·78021·78240·02120·13198Accra2·61750·85651·76100·01910·0662Raw fibreJKL9Ariba0·09336·487·100·02620·080610Machala +Thomé I0·09847·908·640·02720·059011Thomé +Machala0·09197·808·130·02800·077012Cameroon0·10307·137·150·0246—13Thomé I +Samana0·10646·486·750·02580·116214Thomé II,Samana +Accra.0·10756·277·400·03080·100415Accra +Thomé II0·11265·976·470·02900·080116A—5·537·24——17B—5·336·87——18C—5·107·04——19Monarch Ariba (R. & Cie.)0·11659·16—0·0558—20Helios Ariba (R. & Cie.)0·12668·72—0·0446—aShells0·04999·77—0·38840·0545bGerms0·080510·18———
1) See Table 9 A and Table 10.
The foregoing tables provide us with a general idea of the chemical constituents of the cacao bean, but their distinctive properties, both chemical and physical, still remain to be defined, with which we accordingly proceed, as such data will on the one hand enable us to grasp how loss may be avoided in the manufacture of cacao and chocolate wares, and at the same time render intelligible familiar processes connected therewith.
As we have seen, the following substances occur in cacao in varying amounts:
Like the majority of plants and plant products, the cacao bean consists of vesicles or cells, closed on all sides and arranged in a series of layers. They are constructed of cellular tissue or cellulose, and contain fat, albumen, water, starch, theobromine, cacao pigment, besides sugar and salts in inferior quantities.
There is present in the bean from 6 to 8 percent of water, a factor which bodes well for the proper germination of the seed, as when this latter is deprived of moisture, e. g. in the course of a too thorough drying, it speedily decays. Water is still evident in small quantities even in the largest and almost withered beans, as will be seen on comparison of the foregoing analyses.
As a constituent at the expense of which respiration is effected, fat remains one of the most important resources of plant. It has a twofold excellence in this connection, and firstly as a highly calorifacient and carboniferous substance, and again because such a reserve enables the living organism to oxidise with particular ease, wherefore it is found accumulated in somewhat significant measure in the majority of seeds. When seen under the microscope it appears either as round coherent masses, or as crystalline aggregates clearlydistinguishable from the rest of the cell contents on treatment with a solution of osmic acid. The fat in the cacao bean usually amounts to from 50-56 percent, or one half of the total weight of the shelled beans; the shell also contains from 4 to 5 percent of fat.25The unfermented bean has frequently, in addition to its bitter taste, a most unpleasant flavour, attributable to the rancidity of its fatty contents.
The raw bean contains rather more fat than the roasted bean, for whilst the one averages from 50 to 55 percent, there is seldom more than 48-52 percent in the other. The cause of this phenomenon may be connected with the enrichment of the shells in fat, and in some instances, as when the beans are over-roasted, is to be ascribed to the chemical change which the play of burning heat on fatty bodies involves, when a destructive decomposition of the whole ensues, with formations of acroleine. Chemically considered, cacao butter consists of a mixture of so-called esters, or compounds connected with ether, such as the glycerides of fatty acids, and contains, in addition to stearine, palmatine, and laurine26, the glyceride of arachidic acid. It was also formerly supposed that formic, acetic and butyric acids were among the constituents of this ingredient, but the view has been proved erroneous by Lewkowitsch27; similarly, the presence of theobromic acid alleged by Kingzett28has been called into question by Graf.29
Cacao butter is a fairly firm fat of pleasant taste and smell, which varies in colour between yellowish white and yellow. When freshly expressed, it has frequently a brownish shade, passing after a short time into a pale yellow, and turning almost white on long keeping. The brown colour is due to pigment in suspension, which becomes sediment in the course of melting, when the butter asumes a normal colour, referrible to pigment dissolved in the butter oils, and secondarily to a dissolution of the products of roasting in these liquids, rather than to any matter in suspension. The pleasant smell and taste of cacao butter is probably closely allied to the dissolved substances mentioned.
The fat extracted from cacao by solvents differs essentially from that obtained by hydraulic pressure, a fact overlooked in someof even the most recent experiments, and which therefore cannot be too strongly emphasised. Extracted fat is yellowish white, sometimes approximating to grey, and after having been kept a long time, the whole becomes tinged with an actual whiteness, which first attacks the outer surface, and then rapidly progresses towards the centre in concentric paths, and which is a sign of rancidity. Its fracture is partly granular, the smell is not so pronounced as that of expressed fat, being even unpleasant at times, as in the case of faulty wares (but compare page), and it has a keen taste. Cacao butter does not, as is generally supposed, keep better than other vegetable fats, but is equally liable to become rancid, as Lewkowitsch30demonstrates. By rancidity is denoted that state of offensive taste and smell acquired by fatty substances on longer or shorter keeping and especially when they are not properly stored. What chemical re-arrangements of the respective constituents this state presupposes is very questionable; though it appears from the experiments of Lewkowitsch30and others31that the formation of acids does not play as prominent a part as the experimenter is inclined to think, nothwithstanding the marked increase in quantity which may occur. The primary cause of rancidity will rather be found in the oxidation products of the glycerine contained in all fats.
The specific gravity of cacao butter varies considerably, according as it has been expressed or extracted by means of solvents. White32asserts that it can only be determined when the liquefied oil has been solidified several days. According to Rammsberger the specific gravity of expressed butter is 0·85; that of butter extracted by treatment with ether figures at 0·958. Hager gives the normal specific gravity of fresh cacao butter at 15° C. as from 0·95 to 0·952; stale butter 0·945 to 0·946, and the same figures have been confirmed by other investigations, though Dietricht gives 0·98 to 0·981 at 100° C. The melting point is generally regarded as 33° C.; there is in this respect, however, a great difference between the two descriptions of fat. Expressed fat which has been kept for some length of time melts between 34° C. and 35° C., and these figures remain constant, so that it is advisable to read the melting point of fat which hasbeen in store some time rather than that of the fresh pressed product, and take this as a standard. All other fat shows a lower melting point.
As the melting point of freshly melted cacao butter shows considerable fluctuation, the liquid fat must be kept in darkness and cooled with ice for about a week, and the reading should not be taken before the expiration of this time, as only then is it possible to obtain any definite and final result.
Experiments on the melting point of cacao butter as carried out by Zipperer under special conditions yielded the following values; cf. also Table 12.