Spices and How to Know Them

Balsam in benzol and glycerine jelly are desirable for mounting media, and some wax sheets will be needed for making cells. In addition, the analyst should supply himself with specimens of whole spices, starches, and known adulterants, which may be used to become acquainted with the forms and appearances to be expected; it is easier to begin one’s study in this way on sections prepared with the knife, and afterwards the powdered substance may be taken up. To study the physiological structure in the spices and their adulterants is quite difficult, as the vegetable tissues which make up the structure of the spices and the materials of a vegetable origin which are added as adulterations consist of cells of different forms and thickness; those which are most prominent and common are the parenchyma, the sclerenchyma fibrous tissue, and the fibro-vascular bundles. Spiral and dotted vessels are also common in several of the adulterants, and in the epidermis are other forms of tissue which it is necessary to be well acquainted with, though not physiologically. The parenchyma is the most abundant tissue in all material of vegetable origin, making up the largest proportion of the main part of the plant. It is composed of thin wall cells which may be recognized in the potato and in the interior of the stems of maize. In the latter plant, also, the fibro-vascular system is well exemplified, running as scattered bundles between the nodes or joints. Fibrous tissue consists of elongated thick-walled cells of fibers which are very common in the vegetable kingdom and are well illustrated in flax, but they are not so commonly used for adulterating purposes. They are optically active, and in the shorter forms they somewhat resemble the cells next described. They are seen in one of the coats of buckwheat hulls and in the outer husks of the cocoanut. The sclerenchyma is found in the shells of many nuts and in one or two of the spices, the cells being known as stone cells, from the great thickening of their walls. To them is due the hardness of the shell of the cocoanut, the pits of the olive, etc. (See Fig. 1.) Spiral and dotted vessels are common in woody tissue and are readily recognized. All these forms an analyst should make himself familiar with. In pepper and mustard the parenchyma cells are prominent in the interior of the berry, while those constituting the outer coats are indistinct in the pepper, because of their deep color; but in the mustard are characteristics of this particular species. In fact, in many of the spices, and especially those which are seeds, the forms of the epidermal cells are very striking, and, if no attempt is made to classify them their peculiarities must be carefully noted, as the recognition of the presence of foreign husky matter depends upon a knowledge of the normal appearance in any spice. The fibro-vascular bundles are most prominent in ginger and in the barks, while in the powdered spices they are found as stringy particles. The sclerenchyma, or stone cells, as shown in Fig. 1, are common in the adulterant, especially in cocoanut shells, where may also be seen numerous spiral cells, and in the exterior coats of fibrous tissue. As to aids to distinguish these structures, the following peculiarities may be cited: [Illustration: Fig. 1. STONE CELLS Fig. 2. STARCH STAINED WITH IODINE Fig. 3. _Starch, plain_ Fig. 4. POTATO STARCH Fig. 5. _Potato_] The stone cells and fibrous tissue are optically active, and are, therefore, readily detected with polarized light, shining out in the dark field of the microscope as silver-white or yellowish bodies. The fibro-vascular bundles are stained deep orange brown with iodine, owing to the nitrogenous matter which they contain, while parenchyma is not affected by this reagent, aside from the cell contents, nor has it any action on polarized light, remaining quite invisible in the field with crossed prisms. Next to cellular tissue, starch is the most important element for consideration in the plant, which possesses an organized structure and is distinguished by its reaction with iodine solution, which gives it a deep blue or blackish-blue color, varying somewhat with different kinds of starch and with the strength of the reagent, and its absence is marked by no blue color under the same circumstances. Heat, however, as in the process of baking, so alters starches, converting them into dextrine and related bodies, that they give a brown color with iodine, instead of a blue-black; they are no longer starch, however; their form, not being essentially changed, permits of their identification, with a study of the size and shape of the granules of the hilum, or central depressions of nucleus, and the prominence and position of the rings. By polarized light and selenite, the starches of tubers showed a more varied play of colors than the cereal and leguminous starches which are produced above ground. The starches we are to consider are those of a limited number to be met with in spices and their adulterants, and one must be able readily to recognize the following: STARCH NATURAL TO SPICES AND CONDIMENTS Ginger, Pepper, Nutmegs, Cassia, Pimento, Cinnamon, Cayenne. STARCHES OF ADMIXTURES Wheat and other Cereals: Corn, Oats, Barley, Potato. Maranata and other arrowroots: Rice, Beans, Peas, Sago, Buckwheat. No one of these is complete in itself, but from the characters given, and with the aid of illustrations, the starches which commonly occur in substances which are here considered may usually be identified without difficulty. For the benefit of those who have had no experience with the microscope, I will give the following directions: Take a small portion of the starch or spice to be examined upon a clean camel’s hair brush and dust it upon a common slide, blow the excess away and moisten that retained with a drop of a mixture of equal parts of glycerine and water, or with glycerine and camphor water, and cover with a glass. It is well to have a small supply of the common starches in a series of tubes which can be mounted at any moment and used for comparison. They may be permanently mounted by making with cork borers, of two sizes, a wax cell ring equal to the diameter of the cover glass and, after cementing the cell to the slide with copal varnish thinned with turpentine and introducing the starch and glycerine mixture, fixing the cover glass on after running some of the cement over the top of the ring. A little experience will enable one to put the right amount of liquid in the cell and to make a preparation that will keep for some time. After several months, however, it is hard to distinguish the rings which mark the development of the granule, and it is better to keep it fresh. For other purposes, the starches should be mounted in prepared Canada Balsam, or by well-known methods in which they may be preserved indefinitely, but they are scarcely visible with ordinary illumination and must be viewed by polarized light, which will bring out distinctive characters not seen as well, or not at all, in the other mounts. When mounted in the manner described, in glycerine and water, or in water alone, if for temporary use, under a microscope with one objective of equivalent focus of one-half to one-fifth inch, and with means for oblique illumination, the starches will display characteristics which are illustrated in Figs. 2, 3, and 4. The illustrations have been drawn from Nature; Fig. 2 gives starch stained with iodine; Fig. 3 gives shape and size of plain starch, and presence or absence of a nucleus, or hilum, and of the rings and their arrangements which can be made out. The starch is classed in its proper place. If mounted in balsam, their appearance is scarcely visible under any form of illumination with ordinary light, the index refraction of the granules and the balsam being so similar, but when polarized light is used the effect is a striking one. (See plates of ginger, where it is easy to distinguish all the characteristics, except the rings, the center of the cross being at the nucleus of the granule.) The principal starches which are met with may be described as follows in connection with illustrations given, beginning with those of the arrowroot class, including potato, ginger, and tumeric. [Illustration: Fig. 6. & Fig. 7. POTATO STARCH Fig. 8. MARUNTA STARCH Fig. 9. & Fig. 10. _Marunta_] POTATO STARCH Potato starch grains are very variable in size, being found from .05 to .10 millimeter in length, and in shape from oval and allied forms to irregular, and even round in the smallest; these variations are illustrated in Fig. 4, but the frequency of the smaller granules is not as evident as in Figs. 5 and 6. The layers in some granules are very plain and in others are hardly visible. They are rather more prominent in the starch obtained from a freshly cut surface. The rings are more distinct near the hilum, or nucleus, which in this, as in all tuberous starches, is eccentric, shading off toward the broader or more expanded portion of the granules. The hilum appears as a shadowy depression (Fig. 4) and, with polarized light, its position is well marked by the junction of the arms of the cross. It will be found by comparison of Fig. 6 and Fig. 7, that in the potato it is more often at the smaller end of the granules, and that in the arrowroot it is at the larger. With polarized light and a selenite plate a beautiful play of colors is obtained. The smaller granules, by their nearly round shape, may be confused with other starches, but their presence at once serves to distinguish them from Maranta or Bermuda arrowroot starch. Rarely, compound granules are found composed of two or three single ones each within its own nucleus. Of the same type as the potato starch are various arrowroots. The only ones commonly met with in this country are the Bermuda, the starch of the rhizome of Maranta arundinacea, and the starch of tumeric. MARANTA STARCH The granules are not usually so varied in size or shape as those of the potato, as may be seen in Figs. 8, 9, and 10. They average about .07 millimeters in length. They are about the same size as the average of those of the potato, but are never found as large or as small. This fact, together with the fact that the end at which the nucleus appears is broader in the Maranta and more pointed in the potato, enables one to distinguish the starches without difficulty. With polarized light, the results are similar to those seen with potato starch, and, by this means, the two varieties may be readily distinguished by displaying, in a striking way, the forms of the granule and the position of the hilum, as is illustrated in Figs. 8 and 9. CIRCUMA Circuma, or tumeric starch (Fig. 11), though of the arrowroot class, is quite distinct in appearance from these we have described, being most irregular in outline, so that it is impossible to define its shape or to do more than to refer to the illustration. Many of the granules are long and narrow and drawn out to quite a point. The rings are distinct in the larger, and the size is about that of Maranta. Ginger starch (Figs. 12, 13, and 14) is of the same class as potato and Maranta and several others which are of underground origin. In outline, it is not oval like those named, but is more rectangular, having more obtuse angles in the larger granules and being cylindrical or circular in outline in the smaller; its average size is nearly the same as Maranta starch, but it is much more variable in size and form, the rings being scarcely visible even with most favorable illuminations. Fig. 12 shows ginger adulterated. ------------------------------------------------------------------------ [Illustration: Fig. 15. BEANS Fig. 16. _Beans_ Fig. 17. PEAS Fig. 18. _Peas_. Fig. 46. CINNAMON ADULTERATED] [Illustration: Fig. 21. _Pepper_ Fig. 27. RICE STARCH Fig. 28. RICE STARCH Fig. 29. _Rice_ Fig. 42. P. D. PEPPER Fig. 43. PEPPER ADULTERATED] LEGUMINOUS STARCHES Such as those of beans and peas (Figs. 15, 16, 17, and 18), produce but a slight effect under polarized light; the rings are scarcely visible, and the hilum is stellate or much cracked along a median line. This characteristic is more marked in the bean than in the pea. In the latter it resembles fresh dough kneaded again into the center as in making rolls, and in the former the shape assumed by the same after baking. In both it varies in size from .025 to .10 millimeter in length. NUTMEG STARCH Fig. 19 has rings scarcely visible and not iridescent with polarized light. It is smaller in size than the preceding, which it resembles, being at times as long as .05 millimeter down to smaller than .005 millimeter, and of extremely irregular form, having angular depressions and angular outlines. It is distinguished by a budded appearance caused by the adherence of small granules to the larger.