THE TROPICAL AGRICULTURIST. 



[September i, 1S83. 



nnoi 

 0002 



Ci-607 



•41 

 -lo2 



THE OOJIPOSITIOX AXD ADULTERATION OF 

 TEA, COFFEE, SUGAR, &c. 

 Coffee lias, like tea, btieii the subject of numerous in- 

 vestigations, but the following analysis by Payen is most 

 frequently quoted: 



Cellular Tissue 34-00 



Hygroscopic Moisture 1200 



Fat 13-00 



Starch, Sugar, Dextrin, ami Vegetable Acids - 15-50 



Leguniiu 10-00 



Ohlorogeuate of Potash and Caffeine - - 3-5 to 5-0 



Nitrogenous portion 3-00 



Free C'atteiue 0-80 



Thick insoluble Ethereal Oil 

 Aromatic Oil - - - - - 



IVIineral Constituents e-(iU7 



We have obtained the following results from two samples 

 of coffee both in the raw and^roasted condition: 



Mocha. East Indian. 



Raw. Roasted. R-iw. Roasted. 

 Caffeine- - - - I'US -82 1-11 105 



Saccharine Matter - - 955 -43 8-30 



Caffeic Acids - - - 8'-l« 4-74 yoS 



Alcohol Extract coutainmg 

 Nitrogenous and Coloiu- 



ing Matter- - - 6-90 14-14 4-31 12-67 



F-,tandOil - - - 12<50 13-59 11-81 13-41 

 Legrimin or .\lbumin - 9-87 11-23 11-23 1313 

 DeSrin- - " " ■« 1-24 -Si 1-38 



Cellulose aud Insoluble 



Colouring Matter -37-95 18-62 38-fiO 47-42 

 kX - - - 3-74 4-56 3-98 1-13 



Mc^ture- - - - 8-98 063 9-6 4. 1-13 



100-00 100-00 10000 100-1 10 

 Thus the large quantity of caramel produced in chicory 

 1 some other roots in the process of roasting, furni.shes 

 thP means of applying a simple and convenient preliminary 

 test for detecting their pi-esence in coffee. 



When a few grains of coffee coutainmg chicory are 

 1 p1 on the surface of water in a test-tube or wineglass, 

 X \vivticle of chicory becomes surrounded by a yellomsh- 

 l^mwn-coloured cloud which rapidly diffuses itself m streaks 

 tbvm..'h the water, till the whole acquires a brownish colour. 

 Other sweet roots when present mil produce under like 

 conditions the same effect as chicory, but not so rapidly 

 coiiuii.u ^^^ latter. Pure coffee under similar 



'"'^^t'^nns^vesuo sensible colour to the water until after 

 t^rCe o^about a .luarter of an hour. The relative 

 nnfnurTe power of coffee, chi cory, and a vai-iety of other 

 vplptabll substances used in the adulteration of coffee was 

 determined by Messrs. Graham, Stenhouse, and Campbell. 

 This was done by infusing equal quantities of each sub- 

 stance in water, as in the preparation of coffee for dom- 

 »ltir use filtering the infusions and obser^nng the colour 

 ,-r Mass tubes of about I inch in cUameter. The solutions, 

 whiiweTe prepared, at 212= F. (100= C), were made 

 verv dilute, and. for comparison a standard solution was 

 «?epared by dissoh-iug 1 part of caramel, carefully made 

 frnm cane-su^ar in 2.000 p:irts oE water. To produce a 

 deuth of colour equal to that of the standard solution, a 

 lareer proportion of the adulter.ating substance is requu-ed, 

 than the 1 in 2.000 of the standard. 



The following table exhibits the actual weights required 

 c ir„i, =nV,«tnnce when roasted and prepared in imitation 

 of coffee to be di^Sved in 2,000 parts of water, to pro- 

 duce an equal depth of colour:— 

 Caramel 



Mangold Wurzel .- 



Bouka (a coffee substitute) 

 Pd.ack Malt 



Carrots ■■• --: 



Chicory (darkest \orkshu-e) 



Maize 



Rye 



Red Beet 



Bread Ra.spings 



Acorns ,---„„ -" 



Highly roasted (offee ... 



Medium-roasted Coffee ... 



■\\niite Lupin Seed 



Peas 



Beans 



l-OO 

 L-06 

 1-56 

 1-82 

 2-00 

 2-22 

 2-80 

 2-86 

 3-33 

 3-34 

 5-00 

 5-77 



n-95 



10-00 

 13-53 

 13-33 



It will thus be seen that 200 parts of carrot, or 2'22 

 of chicory, have the same colouring power as O'Oo parts of 

 medium-roasted, or 577 of highly-roasted coffee, or of 3-G4 

 parts of bread raspings, or 1333 parts of roasted beans. 

 Another respect iu which infusions of coffee, chicory, 

 and some other substances differ from one another is that 

 of their specific gravities. Wheu, in a sample of coffee, 

 the adulterant has been identified by a microscopical ex- 

 amination, the (Ulfereuce in the densities of the infusions 

 becomes immediately available for estimating the propor- 

 tion present. In preparing the infusion, 100 graius of the 

 ground substance are placed in l,OilO grains by measure of 

 distilled water. The temperature of the mixture is then 

 raised to the boiling-point, where it is maintained for half 

 a minute. The resulting infusion is next filtered, and the 

 specific gravity of the filtrate taken at a temperature of 60 ° 

 F. (15-5° O.) This will be fouud to vary according to the 

 substance employed, in the manner shown iu the subjoined 

 table: — 



Specikic Geavities of Solutions A-r 60' F. 



One part of Substance to 10 parts of water. 



Lupin Seed ... ... 10021 



Acorns ... ... iri02-9 



Peas ... ... ... 10073 



Mocha Coffee ... ... 10080 



Beans ... ... ... lOOS-4 



Plantation Ceylon Coffee ... lOOS-7 



Java Coffee ... ... 1008-7 



J:imaica Coffee ... ... 1008-7 



Costa Rica Coffee ... ... 1008-9 



Carrots ... ... ... 1017*1 



Black Malt... ... ... 1021-2 



Turnips ... 1021-4 



Rye Malt ... ... ... 10216 



English Chicory ... ... 11121-7 



Red Beet ... ... ... 1022-1 



Mangold Wui-zel ... ... 10235 



Maize ... ... ... 1025-3 



It will be seen from this table that the low specific 

 gravity of the coffee infusion distiuguishes it from the roots 

 and cereals. If an infusion of a sample of coft'ee contain- 

 ing 20 per cent of i-ye malt were prepared in the manner 

 described, its specific gr.avity would rise above lX)9-5 —the 

 number corresponding to the infusion of coffee of the 

 highest density — and would approach 1021-6 — the number 

 corresponding to rye malt — almost exactly iu the propor- 

 tion in which the latter was present. 



There is a considerable difference between the quantity 

 of sugar present in roasted coffee and in many of the 

 vegetable substances used for its adulteration, particularly 

 chicory and the other sweet roots, and it is sometimes 

 practicable to make this the means of affording confirm- 

 atory proof of adulteration. 



The amouut of sugar in coffee, and in a great variety 

 of vegetable substances, has been deterniied. both before 

 and after roasting, by the process of fermentation and 

 distillation. 



The ri-sults obtaineil by Messrs Grah.am, Stenhouse, aud 

 Campbell are given iu the follon-iug tables: — 



Varieties of Coffee. Sugar per cent. 



Raw Rousted 

 Plantation Ceylon ... ... 7-52 1-14 



Java ... ... ... ... 6-73 0-4« 



Costa Rica ... ... ... 672 049 



J.amaica ... ... ... 778 0-0 



Mocha ... ... ... 7-40 0-50 



„ ... ... ... 6-40 0-0 



EngUsh :'5-J3 17-98 



English (Torkshu-e) ... ... 32-00 9-86 



Mangold AVurzel ... ... ... 2368 990 



Carrots (ordinary)... ... ... 31-98 11-53 



Tm-nips „ " ... ... ... 3(r.l8 96 



Beet Root (red) ... .. ... 24-06 17-24 



Par.snips ... ... ... 21-70 6-9S 



The fermentation test has the advantage of being easily 

 applied, and the results might, iu combination with the 

 microscope, prove useful in some cases. In applying the 

 test, the process described when treating of sugar is fol- 

 lowed. 



There are some cases in which the character of the 

 ash affords e\idence of adulteration. The ash of coff'ee 

 is distinguished by the absence of soda, and also by the 

 extremely small proportion of silica it contains, the amoimt 



