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:—
| Black pepper | 52 |
| White pepper | 60 |
| Palm-nut meal | 22·6 |
| Pepper husks | 16·3 |
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:—
| Per cent. | |
| Pepper husks | 50 |
| Palm nut meal | 30 |
| Pepper dust | 15 |
| Paprika | 1 |
| Brick-dust | 4 |
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:—
| Seeds. | Husks. | Entire Fruit. | |
| per cent. | per cent. | per cent. | |
| Water and volatile matter at 100° | 8·12 | 14·75 | 11·94 |
| Nitrogenous substances, as protein | 18·31 | 10·69 | 13·88 |
| Fat | 28·54 | 5·48 | 15·26 |
| Ethereal extract (free of nitrogen) | 24·33 | 38·73 | 32·63 |
| Fibre | 17·50 | 23·73 | 21·09 |
| Ash | 3·20 | 6·62 | 5·20 |
| Nitrogen | 2·93 | 1·71 | 2·22 |
A commercial brand of the same article had the following composition:—