Black Pepper is the dried unripe berry of Piper nigrum; white pepper, which is much less in use, being the same fruit deprived of its outer skin by maceration in water and friction. The more important constituents of pepper are an alkaloid (piperin), the volatile oil, and the resin, and upon these ingredients its value as a condiment depends. The partial composition of genuine pepper, as given by Blyth, is shown below:—

The percentages of piperin, resin, extract, and ash are calculated on the sample dried at 100°. KÖnig’s analysis of pepper is as follows:—

Heisch[141] has analysed several varieties of pure and commercial pepper, with the following results:—

The same authority regards 50 per cent. of starch as the minimum standard for unadulterated pepper. The granules of pepper-starch are characterised by their exceedingly small size, being only about ·008 mm. in diameter.

The proportion of ash in genuine pepper seldom exceeds 7 per cent., of which not over 1/10th should consist of sand; but in the commercial article, the total ash often approximates 10 or 12 per cent., 40 or 50 per cent. of which is sand and other insoluble substances.

Composition of Pepper Ash.

The list of adulterations used as admixtures to pepper, as well as to most other ground condiments and spices, is quite extensive, and includes such cheap and neutral substances as ship-bread, corn, ground cocoanut shells, beans, peas, hulls of mustard seed, sand, etc., etc. It is stated that in England large quantities of preparations consisting of linseed-meal, mustard husks and rice-meal, known to the trade respectively as P.D., H.P.D., and W.P.D., are very generally employed in the adulteration of pepper. P.D. (pepper-dust), would appear to also signify the sweepings collected from pepper factories, and sometimes fortified with cayenne, the manufacture of which article has given rise to a special industry. It is utilised as a diluent of the various spices, the sophisticated products being sold as “P.D. pepper,” “P.D. cloves,” “P.D. cinnamon,” etc. Unfortunately the character of most of the adulterants of pepper, as of other spices, is such, that little assistance is afforded the analyst by chemical tests. A microscopic examination of the suspected sample furnishes far more trustworthy information and should in all instances be employed, comparative observations being made with an article of known purity.

The appearance of several of the starch granules of various flours often found in adulterated condiments and spices is represented in Plate IX.

In the special case of pepper, it is of advantage to make chemical determinations of the moisture, ash, piperin and resin.

Moisture.—The proportion of moisture is estimated by the ordinary method of drying a weighed portion of the pepper in a platinum capsule at 100°, and noting the loss in weight sustained.

Ash.—The dry sample is incinerated, and the amount of mineral residue determined. As already intimated, the proportion of sand present is of especial import.

Piperin and Resin.—The pepper is repeatedly digested with absolute alcohol, the mixture filtered and the filtrate evaporated to dryness over a water-bath. The extract is weighed and then treated with sodium hydroxide solution, in which the resin is soluble. The alkaline liquid is then removed, and the remaining piperin dissolved in alcohol, the solution filtered, evaporated to dryness, and the weight of the residue determined. The proportion of piperin in unadulterated pepper ranges from 4·5 to 5·5 per cent., that of resin from 1·7 to 2 per cent.

Niederstadt,[142] from the results of his investigations, concludes, that genuine pepper should yield as much as 7·66 per cent. of piperin, and employs this factor for estimating the purity of mixtures; thus, a sample adulterated with palm kernels and husks, to the extent of about 80 per cent., contained but 1·62 per cent. of piperin.

Pepper contains a greater proportion of starch than some of the substances employed in its adulteration. The following method, suggested by Lenz,[143] may be used for the determination of this constituent:—4 grammes of the sample are digested for several hours in a flask with 250 c.c. of water, with occasional shaking, and the decoction decanted upon a filter. The residue is washed and returned to the flask, which is filled with water to a volume of 200 c.c., 20 c.c. of hydrochloric acid (sp. gr. 1·121) are added, the flask connected with an ascending Liebig’s condenser, and heated on the water-bath for three hours. After cooling, the contents of the flask are filtered into a half-litre flask, and the filtrate carefully neutralised with sodium hydroxide and diluted up to the 500 c.c. mark. It is finally tested by Fehling’s solution. The clarification of the hot solution is assisted by the addition of a few drops of zinc chloride. Lenz obtained by this process the following percentages of sugar, calculated on the ash-free substances:—

The application of this method to the examination of commercial American peppers, when they contain as adulterants substances rich in starch, is obviously of little value. A sample of German pepper, sold as “Pfefferbruch,” recently analysed by Hilger,[144] had the following composition:—

Cayenne Pepper.—Cayenne pepper is the ground berry and pods of Capsicum annuum. Its well-known active properties, which were formerly ascribed to an acrid oil termed capsicin, have lately been shown to be due to the presence of the crystalline compound capsaicin (C9H14O5), fusing at 55°, and capable of volatilisation at 115° without decomposition. The proportion of moisture in cayenne pepper is about 12 per cent.; the alcoholic and ethereal extracts should approximate, respectively, 25 and 9 per cent. The ash ranges from 5·5 to 6 per cent., of which nearly one-half should be soluble in water. Strohmer[145] has analysed Hungarian cayenne, known as “Paprika”; his results were as follows:—

A commercial brand of the same article had the following composition:—

The organic adulterants sometimes met with in cayenne (flour, mustard seed, husks, etc.), are detected by means of the microscope. Among the mineral substances said to be employed as colouring agents, such as iron ochre, brick-dust, red lead, and vermilion, the two former are of more frequent occurrence, and may be recognised upon an examination of the ash obtained by the incineration of the sample.

An adulterant of pepper, known in the trade as “Poivrette” or “Pepperette,” has recently made its appearance in England. It forms a cream-coloured powder, much resembling the inner layer of the pepper-berry in bulk and cellular structure, is exported from Italy, and evidently consists of ground olive-stones, as is indicated by the following analyses, made by J. Campbell Brown:[146]—

The extent to which the various forms of pepper are fraudulently contaminated in the United States is illustrated by the fact that, out of 386 samples of the condiment examined by the chemists of the New York, Massachusetts and National State Boards of Health, 236 (or about 61 per cent.) were found to be adulterated.