ARROWROOT. A large proportion of the edible starches obtained from the rhizomes or root-stocks of various plants are known in commerce under the name of arrowroot. Properly the name should be restricted to the starch yielded by two or three species of Maranta (fam. Marantaceae), the chief of which is M. arundinacea; and when genuine or West Indian arrowroot is spoken of it is understood that this is the variety meant. M. arundinacea is probably a native of Guiana and western Brazil but it has long been cultivated in the West Indies and has now spread to most tropical countries. The plant is a herbaceous perennial with a creeping root-stock which gives off fleshy cylin drical tubers, covered with pale brown or white scales and after wards ringed with their scars. When these tubers are gorged with starch, immediately before the season of rest, it is ripe for use. In addition to about 25% of starch, the tubers contain woody tissue, protein, and salts. The arrowroot may be separated on a small scale by peeling the root and grating it in water, when the starch falls to the bottom. The liquor is then drained off and the starch purified by repeated washings. On a large scale the manufacture of arrowroot is conducted with special machinery.
Arrowroot is distinguished by the granules agglomerating into small balls, and by yielding with boiling water a fine, transparent, inodorous, and pleasant-tasting jelly. In microscopic structure the granules present an ovoid form, marked with concentric lines, similar to potato starch, but having the hilum at the thick extremity of the granule instead of at the thin end. In addition to the West Indian supplies, arrowroot is cultivated in Brazil, the East Indies, Australia, and South Africa. The slender much branched stem is 5 or 6ft. high and bears numerous leaves with long narrow sheaths and large spreading ovate blades, and a few short-stalked white flowers.
Tous-les-mois or Tulema arrowroot, also from the West Indies, is obtained from species of Canna, a genus allied to Maranta and cultivated in the same manner. The granules of tous-les-mois are very large. East India arrowroot is obtained from the root-stocks of species of Curcuma (fam. Zingiberaceae), chiefly C. angusti f olia, a native of central India. Brazilian arrowroot is the starch of the cassava plant (Manihot utilissima), which when aggluti nated on hot plates forms tapioca. Tacca or Otaheite arrowroot is the product of Tacca pinnatifida, the pia plant of the South Sea islands. Portland arrowroot was formerly prepared on the Isle of Portland from the tubers of the common cuckoo-pint, Arum inaculatum. Various other species of the arum yield valuable food-starches in hot countries. Under the name of British arrow root the farina of potatoes is sometimes sold. The chief use, however, of potato-farina is for adulterating more costly prepa rations. This falsification can be detected by microscopic exami nation. Arrowroot contains about 82% of starch, and about 1% of proteid and mineral matter.