Nitrates and Nitrites in Pepper.-Comparatively few observations of the amount of nitrates and nitrites in organic substances are on record: it is a subject of some scientific interest, especially since it has been observed that nitrates and nitrites are decomposed in the presence of free oxalic acid. Whether the determination of nitric acid will be of service to the food-analyst or not is unknown; it certainly may be so, if it be found that a substance rich in nitrates is fraudulently mixed with one poor in nitrates.

§ 301. General Composition of Pepper.-In a sample of Penang pepper analysed by the writer:

The following table exhibits some analyses made by the writer in 1876 of genuine black peppers, and may be compared with similar determinations of white and long peppers :—

TABLE XLVIII.-GENERAL COMPOSITION

OF COMMERCIAL PEPPERS.

§ 302. Analysis of Pepper.-The ash and hygroscopic moisture are estimated in the usual manner. The piperin and resin are the most important to determine.

W. Johnstone recommends the conversion of piperin into piperidine. 10 grms. of the pepper are digested at 100° in a closed flask with 25 cc. of water and 25 cc. of alcoholic potash. After from four to five hours' digestion, the flask is cooled and the contents distilled and titrated until the distillate is no longer alkaline.

Piperin decomposes into piperidine, C,H,,N, and piperic acid, CH10O4, which unites with potash; hence it follows that every molecule of piperidine found is equal to a molecule of piperini.e., 1 cc. of d. n. acid used by the distillate indicates 0·0285 of piperin.

An alcoholic extract of pepper practically consists of resin and piperin, so that if the alcoholic extract be determined, and then the piperin by Johnstone's method, this last value subtracted from the total weight of extract, minus any ash, should give approximately the resin.

$303. Adulterations of Pepper.-Pepper has been adulterated for at least two centuries and a half; for Pierre Pomet,* writing in 1614, says: "As the greatest part of pepper, white as well as black, is sold 'battu' (that is to say, powdered), it should only be bought of honest merchants; because all the pepper the retailers sell is no other thing for the white than 'épices d'Auvergne blanchées,' or rather black pepper whitened with ground rice; the black is only the dust either of the crust of bread, grey Auvergne spices, or manignette."

The list of the adulterations enumerated by authors is an extraordinary one. Linseed-meal, rice, pepper leaves, mustard, wheat flour, sago, woody fibre, chillies, rape-seed, potato, spices, capsicum, manignette (otherwise known as Guinea pepper), chicory, rye, powdered leaves of the laurel, which had been previously used to wrap round extract of liquorice, the stones from olives, bone-dust, marine salt, and various mineral adulterations, are all said to have been detected.

However various may be the adulterations in France (where, Chevallier tells us, in Paris alone he is acquainted with a manufactory producing 1200 to 1500 kilogrammes annually of a mixture sold solely for the purpose of adulterating pepper), the only common adulterations of this country were until lately what are known in the trade as P.D., H.P.D., and W.P.D., abbreviations for pepper-dust, hot pepper-dust, and white pepperdust. The first, or P.D., used to be principally composed of

Pomet: "Hist. Gén. des Drogues," 1735. 40

faded leaves, but linseed-meal is now preferred; H.P.D. is chiefly the husks of mustard, and W.P.D. is ground rice.

Olive-Stones, Poivrette, Pepperette.-Towards the end of 1886, considerable consignments of pepper came into English commerce adulterated with poivrette or ground olive-stones.

The olive-stone has an extremely hard endocarp, difficult to grind, and by boiling in dilute sulphuric acid or by heating with potash, the particles become of a reddish colour, and may thus be picked out of mixtures. Microscopically, ground olive-stones will be found to consist mainly of hard prosenchymatous cells; the superficial layers are fibrous, and are in company with numerous vascular bundles; the more numerous cells are short cells of various forms, but all showing frequently pore-canals (see fig. 71). These structures have but a slight similarity to the analogous structures of the pepper-berry.

Fig. 71.-Tissues of the olive-stone, x 160.-ƒ, Thickened fibres with spiral vessels; h, hard cells from the middle layer of the stone; i, inner layer of hard cells, resting on the endothelium, eu; sp, spiral vessels; ep, epidermis, through which may be seen a brown parenchyma; e, embryonal tissue; c, soft cells from the olive fruit occasionally adhering to the olive-stone; C, tissue of the cotyledons.

The specific gravity of pepper is about 1.173, that of olive-stones higher. If glycerin and water be mixed so as to have a density of 1.173 at 15°, the pepper either floats or is suspended, the olive-stones sink. In this way small percentages of olive-stones may be roughly separated.

Advantage has also been taken of the different effect of colouring-matters on pepper and olive-stones. Aniline acetate colours olive-stones yellowbrown, pure pepper remains of a greyish-white. Naphthylamine gives a yellow orange, thalline pure orange. The French chemists use the hydrochlorate of dimethylparaphenylenediamine. The pepper is put in a porce

*

This reagent may be made as follows:-In a porcelain dish 10 grms. of dimethylaniline are mixed with 20 grms. of pure hydrochloric acid; 100 grms. of crushed ice are added, and little by little 100 cc. of a 7 per cent.

lain dish, and a solution of the above-named salt poured direct on the powder; a little water is added, and the whole stirred; if olive-stones are present, they sink to the bottom and are stained a brilliant red colour.

D. Martilli digests for two or three days 1 grm. of phloroglucol in 50 to 60 cc. of HCl, specific gravity 11; the clear solution is decanted. To about half a gramme of the pepper, enough of the reagent is added to just cover it, and the mixture is heated for a few minutes. Poivrette and, generally, similar substances give a reddish-violet colour. On adding water and decanting, the powder left mainly consists of the adulterant. The author has tried this process, and it works fairly well.

It has been proposed by Lenz to take as a basis for calculation the organic matters of the pepper. This is of course obtained by subtracting the hygroscopic moisture and ash from the total weight. The pepper-starch is then converted into sugar, and the sugar estimated; in this way very constant results are obtained, as shown in Lenz's experiments* and also in some determinations on the same lines by Heisch.†

H. Rabourdin's method has for its principle the estimation of the residue not capable of transformation into sugar and soluble matters by boiling with acid. A grm. of the sample is boiled continuously for an hour in 100 grms. of distilled water and 4 grms. of sulphuric acid; the boiling is best carried out in a flask adapted to a vertical condenser. The insoluble matters are washed, dried, and weighed in a tared filter. Rabourdin found that ground genuine black pepper gave, as an average, 35 per cent. insoluble residue; olive-stones, 745 per cent. The author finds,

however, that commercial pure black peppers give from 28 to 46 per cent. insoluble residue, and white peppers from 1 to 32 per cent., and that the most soluble white peppers may be mixed with 10 per cent. of ground olive-stones, and yet that the insoluble residue may not be raised beyond 2 per cent.; hence the method is only adapted to coarse adulterations. On the other hand, by boiling in acid in this way, the residue of a pepper adulterated with olive-stones invariably betrays its composition by the numerous reddish particles mixed with the grey or dark true pepper residue; but for quantitative purposes it is worthless, or nearly so.

Sand is a common adulterant, whether derived from the solution of sodic nitrite. At the end of half an hour, 30 to 40 grms. more hydrochloric acid are added, and 20 grms. of leaf tin. The reduction is allowed to cool for an hour, then the tin is precipitated by granulated zinc. The liquid is filtered, and saturated with sodic carbonate until it becomes cloudy; it is cleared by acetic acid; 10 grms. of sodic bisulphite are added to prevent oxidation, and it is diluted to 2 litres.

Zeit. anal. Chem., xxiii. 501.

Journal de Pharmacie [5], ix. 289-287.

+ Analyst, 1886, 186.

sweepings of the shops, or added as sand, is by no means clear. The sand, of course, influences the weight of the ash, which should never exceed 7 per cent.

Dr. Hassall made some determinations of the ash of some fifteen or sixteen commercial samples of black pepper; of these only one was under 5 per cent., the percentages of the other fifteen being distributed as follows:

One gave between 5 and 6 per cent. of ash.

It is difficult to believe that more than 2 per cent. of unavoidable material dust can get into the pepper by grinding, &c., and the inference naturally is that most of the above samples were adulterated. The maximum percentage of ash from genuine pepper which the writer has obtained is 5.3 per cent.

The sand foreign to the pepper ash is best separated by the chloroform process as used for alum in flour (p. 193). Nearly all the foreign mineral matter sinks to the bottom of the tube, while the lighter starchy matters float.

Besides the formidable list of adulterations already mentioned, the berry itself is not free from manipulation; for, as the merchant judges by the weight of the sample, means are taken to render the lighter sorts equal in weight to the heavy Malabar and Penang, and in order to do this they are macerated in tubs of brine for twenty-four hours, and thus impregnated with salt and water find their way into the market as Malabar; but such samples are quickly recognised by the astute merchant; and the high chlorides, the high ash, the great amount of humidity, could hardly fail to reveal their nature to the analyst.

Accum

As coffee has been cleverly imitated by chicory pressed into the shape of the coffee-berry, so by pressing various pastes into the shape of the pepper-berry has pepper been imitated. Of this adulteration there is the most undoubted evidence. noticed artificial peppercorns made of oilcake, common clay, and Cayenne pepper, and Chevallier, in a recent paper, states that in 1843 he was requested to examine a sample taken from forty bales, in which he found from 15 to 20 per cent. of artificial pepper, composed of pepper-dust, bran, and other matters.*

LEGAL CASE.

Pepper adulterated with Sand, and containing Sago.

At the Cardiff Police-Court, 1875, a grocer was summoned for selling adulterated pepper. The town-clerk conducting the prosecution, had sent a * Art. Pepper in author's "Dict. of Hygiène."