Cassava

The cassava or manioc (Manihot esculenta; also yuca in Spanish, mandioca, aipim, or macaxeira in Portuguese, and mandio in Guaraní) is a woody perennial shrub of the spurge family, that is extensively cultivated as an annual crop for its edible starchy tuberous root. It was originally observed in what are now called Brazil and Paraguay, and today is widely diffused in tropical and subtropical regions, and may be called the "potato of the tropics". All known species and varieties are cultigens.

Description

The root is long and tapered, with a firm homogeneous flesh encased in a detachable rind, about 1 mm thick, rough and brown on the outside. Commercial varieties can be 5 to 10 cm in diameter at the top, and 50 to 80 cm long. A woody cordon runs along the root's axis. The flesh can be chalk-white or yellowish; it breaks like a carrot's, and darkens quickly upon exposure to the air. (For this reason, the skinned root must be kept under water until it is ready to be cooked.) Even under refrigeration, the root's flavor spoils in a day or so, and therefore it is not very popular with supermarkets.

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The root contains free and bound cyanogenic glucosides which are converted to HCN in the presence of linamarase, a naturally occurring enzyme in cassava. In the past, cassava was categorized as either sweet or bitter, signifying the absence or presence of toxic levels of cyanogenic glucosides. The so-called "sweet" (actually "not bitter") cultivars can produce as little as 20 mg of HCN per kg of fresh roots, while "bitter" ones may produce more than 50 times as much (1 g/kg). Bitter varieties must be processed so as to remove the cyanogenic glucosides.

Related Topics:
Cyanogenic - Glucoside - HCN - Linamarase - Enzyme

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