The Encyclopedia Americana (1920)/Arrow-Root

ARROW-ROOT, a fine-grained starch esteemed for making desserts and invalid foods. It is extracted from the underground parts of various tropical plants, especially of the genus Maranta of the family Marantaceæ. The popular name is said to be derived from the practice of the South American Indians who used the freshly dug rootstocks as an antidote for poisoned arrow-wounds. Probably, however, the derivation is from the Indian word ara. The principal species is Maranta arundinacea, indigenous to tropical America and cultivated in the West Indies, India and other warm countries. It is a perennial plant about two feet high, has small white flowers and fruits about the size and form of currants. The rootstocks, which often exceed a foot in length and three-quarters of an inch in diameter, are yellowish white, jointed and covered with loose scales which must be carefully removed before the extraction of the starch, because they impart their disagreeable flavor if allowed to remain. The process of extraction, which is simple but usually crudely practised, is as follows: The rootstocks are dug when a year old, well washed, peeled, beaten to a milky pulp in deep wooden mortars, and well washed to remove the fibrous parts, which are thrown away. The crude starch is next passed through a sieve or a coarse cloth and allowed to stand until the starch has settled, when the water is drawn and the white residue again washed. After again settling, the water is drawn off and the pulp when dried in the sun is reduced to powder. On a large scale arrow-root is manufactured with the aid of specially constructed machinery, but the process is essentially as described. Bermudian arrow-root is considered the best in the market, and next to it is that of Jamaica. The East Indian product is believed to be inferior, perhaps because of adulteration with or substitution of other starches, Practices induced by the great demand and the high prices paid for the genuine. Some of these other starches are obtained from closely related plants, among which may be mentioned certain species of the genera Canna (q.v.). Curcuma (see Turmeric, Manihot (see Cassava), Tacca (q.v.), and Arum. Potato, corn, rice and wheat starch and fine sago are also sold for arrow-root, but may be identified by microscopical examination; the form and markings of the starch grains differ from those of the arrow-root granules. When dry, arrow-root is odorless, but when damp has a slight smell. Like other carbohydrate foods, it is a source of energy, but since it is deficient in nitrogen compounds it should be mixed with eggs, milk or other substances rich in nitrogenous materials, to form a well-balanced diet.

The amount of fecula or starch present in the roots of the Maranta varies according to age, and runs from 8 per cent, in those of the young plants, to 26 per cent when full grown. The latter stage is reached when the plant is 10 to 12 months old; and the roots then present the following composition in 100 parts:

Starch, fecula, or arrow-root	26
Woody fibre	6
Albumen	1½
Gummy extract, volatile oil, and salts	1
Water	65½

Arrow-root is exported in tin cases, barrels or boxes, carefully closed up. It is a light, opaque, white powder, which, when rubbed between the fingers, produces a slight crackling noise like that heard when newly fallen snow is being made into a snowball. Through the microscope the particles are seen to be convex, more or less elliptical, sometimes obscurely triangular, and not very different in size. The dry farina is quite inodorous, but when dissolved in boiling water it has a slight peculiar smell and swells up into a very perfect jelly. Potato starch, with which it is often adulterated, may be distinguished by the greater size of its particles, their coarser and more distinct rings, and their more glistening appearance. Refined sago flour is used for adulteration, many of the particles of which have a truncated extremity, and their surface is irregular or tuberculate. Arrow-root is also sometimes adulterated with rice starch and with the common starch of wheat flour.

The starch of the cassava, manihot or manioc is sometimes imported into Europe under the name of Brazilian arrow-root. Potato starch, carefully prepared, is sometimes sold as English arrow-root; and the farina obtained from the roots of Arum maculatum as Portland arrow-root. Otaheite arrow-root is the starch of Tacca pinnatifida. All these, as well as Oswego and Chicago corn flour — the starch of maize or Indian corn — are so nearly allied to true arrow-root as not to be certainly distinguishable by chemical test; but the forms of the granules differ, so that they can be distinguished by the microscope.