Saccharum (U. S. P.)—Sugar.
FORMULA: C12H22O11. MOLECULAR WEIGHT: 341.2.
"The refined sugar obtained from Saccharum officinarum, Linné, and from various species or varieties of Sorghum (Nat. Ord.—Gramineae); also from one or more varieties of Beta vulgaris, Linné (Nat. Ord.—Chenopodiaceae)"—(U. S. P.).
COMMON NAMES AND SYNONYMS: Cane-sugar, Sucrose, Refined sugar, Saccharum purificatum, White sugar.
History, Source, and Preparation.—Sugar, which at present constitutes so important an article in the food of all civilized nations, seems to have been known at a very early period to the inhabitants of India and China. It was used only as a medicine for ages after its introduction into the West. But it was not until after the discovery of America, and the introduction of the sugar-cane into the West Indies by the Spaniards, that its use as an article of food became common. About one-half of the total sugar production of the world is from sugar-cane; another equally important source is the sugar-beet (Beta vulgaris, Linné) cultivated chiefly in Germany and Austria, and now to some extent also in this country. The occurrence of sugar in the beet was demonstrated by Marggraf, as early as 1747, but only since about 1840, the manufacture from this source began to flourish. Minor quantities of cane-sugar (sucrose) are produced from several species of Sorghum (e.g., Sorghum saccharatum, Persoon, and Holcus saccharatus, Linné), a Chinese plant, and from the sap of the sugar-maple (Acer saccharinum, Linné, and other species), as well as the sap of the date palm (Phoenix dactylifera), and other palm trees. The crude sugar obtained in India, from the latter source, is called jaggery. Cane-sugar also occurs in corn-stalks, and in the roots of many plants, e. g., parsnips, carrots, and such drugs as ipecacuanha, scopolia, etc.; in the nectar of flowers, and, together with other sugar, in ripe fruits, such as pineapples, pears, apples, bananas, dates, strawberries, etc., while it is entirely replaced by other sugars in figs, grapes, gooseberries, and sweet cherries.
Saccharum officinarum, Linné, Sugar-cane, is a plant having an articulated, juicy root, from which proceed several erect, solid stems, 10 or 12, sometimes 15 or 20 feet high, 1 or 2 inches in diameter, of a hard, shining rind, which is green, while the cane is immature, but turning yellow, purple, red, or striped when the cane ripens. Internally it is whitish, juicy, saccharine, and pithy. The leaves are situated at the joints, at intervals of about 2 or 3 inches, flat, sheathing at the base, 2 to 4 feet in length, about one-fourth as wide, the margins being armed with numerous small, sharp teeth. The panicle is terminal, spreading, erect, oblong, 1 to 3 feet in length, and grayish from the quantity of long, loose hairs surrounding the florets; the branches are alternate and very spreading. Rachis striated. Florets dioecious in pairs. Glumes smooth. Paleae smooth, membranous, and of a pink color. This plant, a native of tropical and subtropical climates, is cultivated in the East and West Indies, Mauritius, Tahiti, the Sandwich Islands, and in some of the southern United States.
In cultivation, the canes are not allowed to flower, because the yield of sugar is greatest from non-flowering canes. (For interesting details regarding the cultivation of sugar-cane, and connected matters, see Henry Pocklington, Pharm. Jour. Trans., Vol. V, 1875, p. 746.) When the canes turn yellow, they are cut and transported to the sugar-mills, where the juice is obtained by crushing the canes between revolving cylinders of stone or, preferably, iron. The resultant cane-straw is called bagasse, and is used as fuel. Sugar-cane, when matured, contains about 90 per cent of juice, which holds, on an average, 18 per cent of cane-sugar, with small quantities of uncrystallizable (invert) sugar. The latter kind occurs mostly in the upper part of the stem; it is more abundant in rapidly-growing cane than in cane of slower growth. Cane-juice also contains about 9 per cent of a peculiar albuminous matter, which readily undergoes putrefaction; likewise, small quantities of organic acids, e. g., oxalic and malic acids, and aconitic acid (A. Behr, 1877), a derivative of citric acid, are present. These constituents cause cane-juice to be rapidly decomposed in warm climates; the acids tend to convert sucrose into uncrystallizable invert sugar. Hence, the juice must be immediately worked for sugar, by neutralizing the free acid with a calculated quantity of milk of lime; after boiling and removing the scum (defecating), the juice is gradually evaporated in a series of open pans (old method), or by means of vacuum pans, i. e., under diminished pressure at a lower temperature (modern method). By the old method, the raw, brown, or muscovado sugar is separated from the mother liquor, or molasses, by simple draining in perforated vessels; by the modern method, the molasses is separated from the sugar in centrifugal machines, and the raw sugar thus obtained is frequently pure enough for many purposes. From molasses additional quantities of sugar are frequently obtained; the residual, impure molasses is fermented and used in the distillation of rum. To produce refined, white or loaf-sugar, the raw sugar is sent to refineries, where it is dissolved in water, purified by means of bullock's blood and bone-black, and decolorized by passing the syrup through filters of animal charcoal. It is then evaporated in vacuum pans to crystallization, and the mass is run into conical molds, wherein the molasses (treacle) is either allowed to drain or is separated by centrifugal force. According to Dr. S. P. Sadtler (Indust. Org. Chem., 2d ed., 1895, p. 152), the hard commercial sugars (dried by artificial heat) contain over 99 per cent of pure sucrose, while the softer sugars (merely centrifugated) hold about 4 per cent of water, due to traces of mother liquor adhering to the crystals.
The SUGAR-BEET contains from 12 to 15 per cent of sucrose. Unlike sugar-cane, it is free from uncrystallizable invert sugar, but contains the sugar raffinose. The presence of about 1.25 per cent of nitrogenous matter (betaîne, asparagin, etc.) and a comparatively large amount of salts, make the purification of the raw beetsugar a more complicated operation than that of the sugar from sugar-cane. The molasses from beet-sugar, unlike that from cane-sugar, can not be used for table syrups, on account of its bad taste and smell. It contains about 50 per cent of sucrose, which can be recovered for the most part by precipitating the sugar in the form of calcium sucrate, or strontium sucrate (strontium process). (For further details, we must refer the reader to special works on technology-e. g., see S. P. Sadtler, loc. cit., pp. 119-166.)
Description and Tests.—Cane-sugar (sucrose), as demanded by the U. S. P., occurs in "white, dry, hard, distinctly crystalline granules, odorless, and having a purely sweet taste. Permanent in the air. Soluble, at 15° C. (59° F.), in 0.5 part of water, and in 175 parts of alcohol; in 0.2 part of boiling water, and in 28 parts of boiling alcohol; also soluble in 80 parts of boiling, absolute alcohol, but insoluble in ether, chloroform, or carbon disulphide. The aqueous solution, saturated at 15° C. (59° F.). has the specific gravity 1.345, and is miscible with water in all proportions. The aqueous. or alcoholic solution of sugar is neutral to litmus paper"—(U. S. P.).
An aqueous solution of 850 parts of sugar in water, sufficient to make 1009 Cc., has a specific gravity of 1.317; this solution is the official syrup (formerly called Syrupus Simplex). Cane-sugar melts at about 160° C. (360° F.), and solidifies on cooling, forming a glossy, amorphous mass, called barley sugar; its specific gravity is only 1.509, while that of cane-sugar is 1.606. When heating cane-sugar to about 200° C. (392° F.), a brown-coloring matter, called caramel, is formed. Cane-sugar, upon dry distillation, yields acetone, aldehyde, acetic acid, formic acid, carbonic dioxide, some monoxide, methane, tarry products, etc. Concentrated sulphuric acid converts sugar into a charred mass, sulphurous acid being evolved. Boiling with nitric acid produces saccharic acid (C4H4[OH]4.[COOH]2), tartaric and oxalic acids. By the action of concentrated nitric and sulphuric acid upon sugar, explosive nitro-sugars are formed, analogous to nitro-cellulose (see Pyroxylin). With bases, as calcium and strontium oxide, sugar forms characteristic compounds, called saccharates, or sucrates, e. g., tri-calcium sucrate (C12H22O11.3CaO), which are technically important (see Preparation, preceding page).
Cane-sugar is optically dextro-rotatory, but upon warming with diluted acids, it is converted into invert sugar, which is a mixture of equal molecules of dextrose and laevulose, the combination of which is slightly laevo-rotatory. Measurement of the optical rotation by means of especially devised instruments, is of great importance in the analysis of the various sugars. (For details on this subject, with index of literature, see H. W. Wiley, Principles and Practice of Agricultural Analysis, Vol. III, Easton, Pa., 1897.) Cane-sugar (sucrose) does not reduce Fehling's solution, nor ammoniated silver nitrate, except in traces; reduction takes place freely after inversion by means of acids. Cane-sugar as such ferments, only after it is transformed by the action of yeast into invert sugar; the latter is capable of being fermented.
The U. S. P. gives the following tests for the purity of cane-sugar: "Both the aqueous and the alcoholic solution of sugar should be clear and transparent. When kept in large, well-closed and completely filled bottles, the solutions should not deposit a sediment on prolonged standing (absence of insoluble salts, ultramarine, Prussian blue, etc.). If 1 Gm. of sugar be dissolved in 10 Cc. of boiling water, the solution mixed with 4 or 5 drops of silver nitrate T.S., then about 2 Cc. of ammonia water added, and the liquid quickly brought to the boiling point, not more than a slight coloration, but no black precipitate, should appear in the liquid after standing at rest for 5 minutes (absence of grape-sugar, or of more than a slight amount of inverted sugar)"—(U. S. P.).
Action, Medical Uses, and Dosage.—Sugar is nutritive, alterative, demulcent, diuretic, and topically antiseptic. It belongs to the class of "elements of respiration," contributes to the formation of fat and lactic acid, and, by its oxidation, furnishes heat. It has been detected in the tissue of the liver. As it is void of nitrogen, it can not sustain life alone, and only becomes eminently nutritive when combined with other alimentary proximate principles. Used in large quantities, it is injurious to digestion. In relation to both vegetable and animal matters, it acts powerfully in preventing putrefaction; the former of which may be preserved indefinitely in syrup, so long as the syrup is secured against fermentation; while the latter, after long immersion in syrup, or in moistened sugar, may be perfectly mummefied. On this account it is now used considerably in the preservation of fish, and various meats, instead of salt, to which it is superior, requiring a smaller amount, and not materially affecting the flavor nor the nutritive properties of these meats. Sugar or molasses, when freely eaten by children, prove excellent anthelmintics, and have also proved efficient in scorbutic affections. Powdered white sugar is sometimes sprinkled over ulcers to remove fungus or proud flesh, and has been blown upon the ball of the eye to remove specks on the cornea. As a local application in aphthae, it is quite efficient, and cures have been wrought with it in trachoma. It favors the detachment of diphtheritic membranes, and may be employed as an antiseptic dressing for various kinds of wounds. On account of its property of correcting fetor, a snuff of finely-powdered sugar has been used in ozoena. As a demulcent, sugar may be employed in various forms, in cough, hoarseness, soreness of the throat, etc. When taken to the extent of 12 or 16 ounces per day, dissolved in water, sugar is said to powerfully increase the sexual passion. It has long been supposed that the teeth are injured or acted upon by sugar, in a manner calculated to cause their decay, but this opinion is erroneous; if particles of sugar become lodged between the teeth, and are allowed to decompose, decay will inevitably ensue, but if the particles be removed at an early period, sugar will be found to exert a beneficial influence upon the teeth and gums. The use of it, however, is mainly confined to the preparation of syrups, to conceal the unpleasant taste of several drugs, to render water and oils miscible, to suspend certain medicines in the form of mixture or emulsion, to prevent the oxidation of some chalybeate compounds, and also for converting some agents into the state of conserve, confection, electuary, pill, or lozenge. For pills, molasses is most generally preferable to syrup, as it does not so readily harden, and preserves them in a soft, moist state, for a long time, while its antiseptic properties prevent them from becoming moldy.
Sugar, in solution, absorbs a very large quantity of lime. A saccharate of lime has been found very beneficial in the chronic diarrhoeas of children, as well as to prevent acidity of the stomach, and the disposition to diarrhoea so common in children of a certain age at particular seasons. It is made by saturating simple syrup with lime, and then filtering it. It forms a transparent mixture of an extremely alkaline taste, and may be added to water or milk. It is altogether superior to the bicarbonate of sodium. Dose for an infant, from 1/4 to 1/2 drachm, given in some of the mother's milk; for an adult, from 1 to 2 1/2 drachms.
Related Sugars.—GLUCOSE, or GRAPE-SUGAR (C6H12O6=179.58), known also as DEXTROSE, or STARCH-SUGAR, is found in grapes, cherries, plums, figs, honey, always associated with laevulose and sometimes cane-sugar (which see). Dextrose is the sugar of diabetic urine, and frequently occurs combined in the form of glucosids, such as amygdalin, salicin, phloridzin, quercitrin, etc. (which see). Chemically pure dextrose may be obtained by adding finely powdered cane-sugar, in small portions, to a mixture of 15 parts of alcohol (80 per cent) and 1 part of fuming hydrochloric acid, until the cane sugar is no longer dissolved. Invert-sugar is formed, and from the solution obtained, dextrose (C6H12O6+H2O) crystallizes, while laevulose remains in solution. On a commercial scale, grape-sugar is obtained from starch by boiling it under pressure with diluted sulphuric acid until the conversion of the starch into dextrin and finally into sugar (dextrose and some maltose) is complete. The acid solution is neutralized with calcium carbonate, the solution decolorized with animal charcoal and concentrated in vacuo, either to form commercial "grape-sugar," or the syrup known as "glucose." Commercial grape-sugar contains from 72 to about 73.5 per cent dextrose, from 0 to 3.5 per cent maltose, and from about 4 to 9 per cent dextrin; "glucose syrup" contains from 34 to 42 per cent dextrose, from 0 to 19 per cent maltose, and from 30 to 45 per cent dextrin. Maltose (C12H22O11) is the sugar formed when diastase, the ferment of malt extract, is allowed to act upon solution of starch. Grape-sugar (dextrose) is soluble in water and diluted alcohol, insoluble in ether and chloroform, and crystallizes without combined water, in the form of warty masses, from hot absolute, and from methyl alcohol, also from aqueous solution at 30° to 36° C. (86° to 95° F.); otherwise it crystallizes with 1 molecule of water. In solution, it is optically dextro-rotatory (see Cane-sugar). Pure dextrose is less sweet than sucrose (cane-sugar), 1 1/2 parts of the former being equivalent to 1 part of the latter. Unlike cane-sugar, dextrose is not charred by concentrated sulphuric acid, and is permanent toward acids, while sensitive toward warm alkalies; the latter darken and decompose it, with formation of lactic, formic, acetic, glucic, and saccharic acids (Moore's Test). Solutions of grape-sugar (dextrose) easily ferment when yeast is added, chiefly alcohol and carbonic acid being formed, according to the equation: C6H12O6=2CO2+2C2H5OH. Upon this reaction Dr. Wm. C. Alpers (Merck's Report, 1898, p. 468) bases a gravimetric method for determining the quantity of grape-sugar present in diabetic urine, by allowing it to ferment by means of yeast, and collecting the carbonic acid formed, in a weighed quantity of caustic potash. One Gm. of carbonic acid is equivalent to 2.0458 Gm. of dextrose.
Grape-sugar forms a crystallizable compound with sodium chloride (2C6H12O6.2NaCl+ H2O) which has been incidentally obtained in the isolation of dextrose from diabetic urine. Grape-sugar (dextrose) in alkaline solution is a strongly reducing agent. It reduces Fehling's solution, ammoniated silver solution and alkaline mercuric cyanide (Knapp's) solution, etc. In these and other reactions it behaves as an aldehyde, and is believed to have the graphic formula CH2OH.(CHOH)4.CHO, while laevulose is considered to be a ketone, CH2OH.(CHOH)3.CO.CH2OH. Both sugars are reduced to the alcohol mannit with nascent hydrogen in alkaline solution. An important test for dextrose is that with phenylhydrazine (C6H5NH.NH2). With 2 molecules of the latter it forms dextrosazone which crystallizes in yellow needles, is. almost insoluble in water, crystallizable from warm alcohol, and can be identified by its melting point which lies at 204° C. (399.2° F.). It is prepared by prolonged heating of 1 part of dextrose, 2 parts of the hydrochlorate of phenylhydrazine, and 3 parts of sodium acetate on the water-bath, and recrystallizing the precipitate formed. (For an exceedingly interesting summary of the more recent chemistry of the sugar group, see Amer. Jour. Pharm., 1893, p. 32, from Pharm. Jour. Trans., 1892.)
DETECTION OF SUGAR IN URINE.—A rapid, qualitative test for sugar, if much is present, consists in adding to the warmed suspected liquid a warmed saturated solution of potassium bichromate mixed with sulphuric acid in slight excess. A brisk effervescence ensues if sugar is present, the chromate being reduced to green chromium salt. The presence of albumen, urea, or uric acid does not interfere with this test. The most certain test for sugar is undoubtedly that by means of the optical method, but can be practically employed only in rare cases, since a polarizing apparatus is not always available (see remarks under Saccharum).
Fermentation of the slightly acid specimen with pure yeast at a temperature of about 30° C. (86° F.), and collecting the gas over mercury (or water, in qualitative analysis) is a good test for sugar in urine. A parallel experiment with yeast and a sugar-free urine should always be made. Also compare the gravimetric method, mentioned above. A good qualitative test consists in the formation of the crystals of dextrosazone which must show the melting point 204° C. (399.2° F.) (see above). The best-known test which still gives much satisfaction, is that with Fehling's solution. For the preparation of the latter, see U. S. P. Volumetric Solutions. When testing for sugar, mix in a test-tube equal volumes of the copper and the tartrated alkali solution, and heat to boiling; no reduction must take place. Then add to the deep-blue a few drops or more, of the suspected urine. Mix, and boil again. If a small quantity of sugar is present, the liquid becomes fluorescent, and upon standing deposits a copper-red precipitate; if much sugar is present, the liquid upon warming rapidly turns bright yellow, then cinnabar red, and precipitates at once a copper-red precipitate of cuprous oxide (Cu2O). If uric acid or urates occur in the urine, these must be removed by the addition of a few drops of hydrochloric acid, setting aside for 12 hours and filtering. (For the quantitative determination of sugar by means of this and other tests, see for example, Hammarsten and Mandel, A Text-book of Physiological Chemistry, 2d ed., New York, 1898.)
LAEVULOSE, UNCRYSTALLIZABLE or FRUIT-SUGAR (C6H12O6=179.58), called by Soubeiran Chylariose, is found in sweet fruits and honey, along with grape-sugar; it is likewise obtained with dextrose (grape-sugar) by subjecting cane-sugar to the action of acids. From invert-sugar it may be isolated by means of its calcium saccharate which is less soluble in cold water than that of dextrose. It is not usually crystallized, but it has been obtained in long silky needles, has a very sweet taste, is dissolved in water or alcohol, and wholly parts with its water when heated upon the water-bath. Its solution in water rotates the plane of polarized light to the left. Like grape-sugar, it is capable of direct vinous fermentation (see Honey).
INOSIT, or PHASEO-MANNIT, is a peculiar sugar found in muscle and other organs of the body. The fruits of several leguminous, and other plants, when green, also yield this sugar. It is not fermentable, is very sweet, soluble in water (1 in 6), not soluble in absolute alcohol or ether, crystallizing easily from the first two. With diluted nitric acid, oxalic acid is formed; with concentrated nitric acid explosive nitrates result.