Related entry: Curcas Purgans.—Purging-Nut
The fecula of the root of Manihot utilissima, Pohl (Jatropha Manihot, Linné; Janipha Manihot, Kunth).
COMMON NAMES: Tapioca, Tapioca meal, Brazilian arrow-root.
Botanical Source.—This plant is a native of Brazil, and is cultivated in various parts of South America. It has a large, fleshy, oblong, tuberous root, often weighing 30 pounds, and full of a wheyish, venomous juice. The stems are white, crooked, brittle, jointed, pithy, and usually 6 or 7 feet high, with a smooth, white bark. The branches are crooked, and have on every side, near their tops, leaves irregularly placed on long, terete petioles, broadly cordate in their outline, divided nearly to their base into 5 spreading, lanceolate, entire lobes, attenuated at both extremities. The leaves are dark green above, and pale glaucous beneath; the midrib is strong, prominent, and yellowish-red below with several oblique veins, connected by lesser transverse ones, branching from it. The stipules are small, lanceolate, acuminate, and caducous. The flowers are borne in axillary and terminal racemes, the pedicels having small, subulate bracts at their base. Male flowers smaller than the female. The calyx is campanulate, and divided into 5 spreading segments, purplish externally, fulvous-brown within. The disk is orange-colored, fleshy, annular, 10-rayed; the stamens number 10, alternating with the lobe of the disk. The filaments, which are shorter than the calyx are white, filiform, and free, the anthers yellow and linear-oblong. The female flowers have the same color as the male, and are deeply 5-parted, the segments being lanceolate-ovate and spreading. The disk has an annular, orange-colored ring, in which the purple ovate, furrowed ovary is imbedded; the style is short. Stigmas 8, reflexed, furrowed and plaited, and white. The capsule is ovate, 3-cornered, and tricoccous; the seeds are elliptical, black, and shining, with a thick, fleshy funiculus (L.—W.).
History.—Manihot utilissima, formerly designated by botanists as Jatropha Manihot, furnishes a large amount of food to the inhabitants of southern America, under the names of mandioc, tapioca, or cassava starch. The juice, mixed with molasses, and fermented, produces an intoxicating liquor which is much relished by the negroes and Indians of the West Indies. According to Pohl, there are two distinct species, the bitter and the sweet cassava. The bitter is the more common species, Manihot utilissima above described; its root is much larger, knotty, black externally and contains a bitter and poisonous milky juice. The root of sweet cassava (Manihot palmata, of J. Mueller; Manihot Aipi, Pohl; Jatropha dulcis, Gmelin) is fusiform, brown externally, not exceeding 6 ounces in weight, with a sweet, amylaceous taste, and it is stated that it may be eaten with impunity (see Chemical Composition).
Preparation.—Tapioca is prepared from the bitter cassava. The large, fleshy, and tuberous root is reduced to a pulp, this is washed with cold water in funnel-shaped mat-filters, the starch is allowed to subside in the milky fluid which passes through, and is then elutriated in the usual manner, and finally converted into the granular form by drying it on hot plates. Should any of the volatile poisonous principle remain in the meal previous to drying it, the heat employed for this purpose entirely removes it. Cassava meal, which is obtained by pressing out the poisonous juice from the grated root, drying the remaining solid portion, and finally grinding it, is made into cassava bread by the natives, who bake it in thin loaves. Large quantities of tapioca are now prepared by steam in Malacca.
Description.—Tapioca is a very pure starch in the form of irregular, warty grains, seldom larger than a pea, white, tasteless, and inodorous. Boiling water dissolves it almost entirely, or, if in small proportion to the tapioca, it forms with it a translucent, tasteless jelly, and firmer than is made with most varieties of starch. Cold water partially dissolves it, forming a liquid which yields a blue precipitate with iodine. Under the microscope it is found to consist of aggregated starch globules, about 1/2000 of an inch in diameter, partly broken, partly entire, the broken ones only being soluble in cold water, more uniform than the granules of most other varieties of fecula, with a distinct hilum, which is completely surrounded by rings, and bursts in a stellate manner. The rupture observed in some of the granules is owing to the heat employed in drying (C.—P.). (See also an interesting article on Manioc or Cassava, by Dr. E. Chenery, in Amer. Jour. Pharm., 1890, p. 359.) Tapioca of commerce is frequently prepared from domestic sources, such as potatoes, etc.
Chemical Composition.—The poisonous principle in cassava juice was suspected to be hydrocyanic acid as early as 1796, by Dr. Clark, of Dominica, who pronounced the toxic symptoms caused by it in negroes to be similar to those caused by prussic acid. Dr. Fennor, of Cayenne, shortly afterward isolated the poison by distillation. Subsequently, Messrs. Henry and Boutron-Charlard identified the poison in a specimen of cassava juice as hydrocyanic acid by chemical tests. In recent years, Mr. E. Francis (Amer. Jour. Pharm., 1883, p. 35, from Chem. and Drug., 1882), found hydrocyanic acid not only in the bitter but also in the sweet cassava, the latter (15 samples from Trinidad) containing on an average 0.0168 per cent, the former (10 samples), 0.0275 per cent of prussic acid.
Dr. Eberhard, of Blumenau, Brazil (Amer. Jour. Pharm., 1869, p. 301), found the root of Manihot utilissima to be composed of starch (13.63 per cent), water (61.7 per cent), lignin (23.49 per cent), and ash (1.18 per cent). The starch flour obtainable from cassava is very pure, being nearly all starch (99.1 per cent), with only about 0.5 per cent of protein substances. Dr. H. W. Wiley (U. S. Dep. of Agr., 1895, Bull. No. 44; also see Amer. Jour. Pharm., 1895, p. 262), found in sweet cassava, growing in southern Florida, about 20 to 25 per cent of starch (referred to fresh root), and recommends the cultivation of this root for the economic production of tapioca, glucose, alcohol, and probably cane sugar.
Action and Uses.—Nutritive and demulcent. Used as a light and agreeable nourishment for the sick. It makes an excellent nourishment for infants about the time of weaning, and is less apt to turn sour on their stomach than any other farinaceous food. For the sick and convalescent, its flavor may be improved by raisins, sugar, prunes, lemon-juice, wine, spices, etc., as may be required.