As is the case with mustard and pepper, the adulteration of the ordinary spices is exceedingly prevalent in the United States. Probably those most subject to admixture, are cloves, mace, cinnamon, allspice, and ginger. The fact that these condiments are frequently offered for sale in a ground state furnishes an opportunity to incorporate with them various cheaper vegetable substances, of which the manufacturer too often makes use. For the detection of these additions the use of the microscope is of pre-eminent importance; and, in this regard, no more useful information could be afforded than by quoting the following remarks, furnished to the author by Clifford Richardson, Assistant Chemist of the United States Department of Agriculture, who has lately made a valuable contribution to the literature of spice adulteration.[147]

“Spices consist of certain selected parts of aromatic or pungent plants possessing a characteristic anatomical structure and proximate composition which, when they have been carefully studied and recorded, serve as a means of recognising the pure substances when under examination, and distinguishing them from the different structure and composition of the adulterants which have been added to them.

“To carry on an investigation of this description a limited knowledge of botanical physiology (as well as of proximate chemical analysis) is therefore necessary. For the physiological part, the use of the microscope, as a means of determining structure, is necessary.

“The structure of the plant parts which constitute the spices and their adulterants as well, is characterised by the presence or absence of different forms of cells and of starch, and their relative arrangement. At least, this is as far as it is necessary to go from the analyst’s point of view. By studies of sections of pure whole spices one must become familiar with the forms usually met with in the spices and those which are prominent in adulterants and be able to recognise the presence of starch and by the character of the granules to determine their source.

“The common forms of cells which are met with in the spices, and with which one should be familiar, are known as parenchyma cells, sclerenchyma cells, those of fibro-vascular bundles, spiral and dotted cells, and those of peculiar form in the cortex and epidermis.

“Parenchyma consists of thin-walled cells, such as are well illustrated in the interior of a corn-stalk and are found in the centre of the pepper kernel. They are often filled with starch, as in the cereals and pepper, but at times are without it, as in the mustard seed.

“Sclerenchyma, or stone cells, are of a ligneous character, their walls being greatly thickened. They are commoner in the adulterants than in the spices, and are well illustrated in the shell of the cocoa-nut, in clove stems, and a few are seen in pepper hulls.

“Spiral and Dotted Cells are found in woody tissue, and their characteristics are denoted by their names. They are more commonly found in adulterants, and their presence in large amounts is conclusive, in many instances, of impurity. They may be seen in sections of cedar-wood and in cocoa-nut shells, and to a small extent in pepper husks.

“The Fibro-vascular Bundles, as their name implies, are aggregations which appear to the eye, in some instances, as threads running through the tissue of the plant. They are easily seen in the cross-section of the corn-stalk, and are common in ground ginger, having resisted comminution from their fibrous nature. They are made up of cells of various forms.

“The Cells of the Cortex and Epidermis are in many cases extremely characteristic in form, and of great value for distinguishing the origin of the substances under examination. They are too numerous in shape to be particularly described, and are well illustrated in the husk of mustard, and the pod of Capsicum or cayenne.

“Other forms of tissue are also met with, but not so prominently as to render it advisable to burden the memory with them at first, or to seek them before they are met.

“These forms of cells and their combinations which have been described, present in addition some peculiarities, aside from their structure, which assist in distinguishing them.

“Parenchyma is optically inactive, and is not stained by iodine solution, except in so far as its contents are concerned. Sclerenchyma, the stone cell, is optically active, and in the dark field of the microscope, with crossed Nicols, appears as shining silvery cells, displaying their real structure. The fibro-vascular bundles are stained yellowish brown by iodine, and are thus differentiated from the surrounding tissue.

“Starch is stained a deep blue, or blue black, by iodine solution, and since the contents of the parenchyma cells often consist of much starch, the parenchyma in these cases seems to assume this colour.

“To distinguish some of the peculiarities of structure which have been mentioned requires some little practice and skill, but not more than is readily acquired with a short experience. There are however some aids which should not be neglected.

“In the ground spices it will be found more difficult to recognise the anatomy of the parts than in a carefully prepared section. The hardest parts are often the largest particles, and scarcely at all transparent. The mounting of the material in water or glycerine will render them more so, but it is necessary to employ some other means of which two are available. A solution of chloral hydrate in water, 8 to 5, serves after 24 hours to make the particles less obscure. In many instances also, it has been found advisable to bleach the deep colour by Schulze’s method, using nitric acid of 1·1 sp. gr. and chlorate of potash. When this is done, hard tissue is broken down and rendered transparent where otherwise nothing could be seen. As examples, olive stones and cocoa-nut shells will serve. Without treatment little can be made out of their structure.

“Of course, it is plain that the detection of starch must be in a portion of the material which has received no treatment, and that progress must be made from the least to the most violent reagents.

“For this work an elaborate microscope is unnecessary. It should, for work with starches, have objectives of ½ and 1/5 inch equivalent focus, arrangements for polarising light, and if possible, a condenser system. Many good stands are to-day made at reasonable prices which will serve the purpose.”

The microscopical appearance of various starches in polarised light is shown in Plate IX. Plate XII. exhibits several spices, under polarised light, in a pure and adulterated state. Those represented are:—

Ginger, pure, and adulterated with foreign starch.

Cinnamon and Cassia; the pure barks, ground, showing the relative greater frequency of fibro-vascular bundles in the former.

Cayenne, pure, and adulterated with rice starch.

The chemical analysis of spices, although usually of minor importance, often serves to confirm the results secured by aid of the microscope. The principal determinations required are the ash, oil, starch, and sugar. The more common forms of spice adulteration are the following:—

Cloves.—This spice is said to be sometimes deprived of its volatile oil before being put on the market. In the genuine article the proportion of oil seldom falls below 17 per cent. The oil is readily estimated by distilling the suspected sample with water. The usual adulterants of ground cloves consist of clove-stems, allspice, flour and burnt shells.

Mace.—True mace is frequently mixed with the false spice, the presence of which is indicated by its dark-red colour. The other foreign substances most commonly used are turmeric, wheaten flour, rice, corn meal, and roasted beans.

Cinnamon.—The chief admixtures to be sought for are cassia, ground shells, crackers, etc.

Allspice.—Owing to its cheapness, allspice is probably less adulterated than the preceding spices. The addition of mustard-husks, ground shells, and clove stems, and the removal of the volatile oil, are, however, sometimes practised. The oil in genuine allspice should amount to about 5 per cent.

Ginger.—Ginger is likewise comparatively little exposed to sophistication, although it has occasionally been found coloured with turmeric, and admixed with corn meal, mustard-husks, cayenne, and clove stems. It is stated that the manufacturers of ginger extract dispose of the exhausted article to spice dealers who utilise the impoverished product for the adulteration of other spices.

Mixed Spices.—These consist of mixtures of the foregoing, and are liable to the sophistications practised upon their ingredients, the addition of the cheaper flours and starches being especially prevalent.

The following table shows the results of the examination of various spices, lately officially made in the States of New York and Massachusetts, and by the National Board of Health in Washington:—