Yuca Cassava

Cassava is exceptionally drought-tolerant and able to grow productively on poor soil. Cassava leaves are consumed as a vegetable. In countries such as the Democratic Republic of the Congo, Zambia, Tanzania, Sierra Leone, Liberia and Guinea, younger and tender cassava leaves are a major component of the diet.

Origin and Production

Manihot is a genus in the milkspurge family, Euphorbiaceae. The best known member of this genus is the widely cultivated cassava. The cassava plant is easily established by cutting. In 2022, world production of cassava root was 330 million tonnes, led by Nigeria with 18% of the total. Other major growers were the Democratic Republic of the Congo and Thailand. Thailand is the largest exporter of cassava starch.

Chemistry and Toxicity

Cassava is grown in sweet and bitter varieties; both contain toxins, but the bitter varieties have them in much larger amounts. Sweet cultivars can contain as little as 20 milligrams of cyanide per kilogram of fresh roots, whereas bitter cultivars may contain as much as 1000 milligrams per kilogram. Linamarin is a cyanogenic glucoside found in the leaves and roots of plants such as cassava. The generation of cyanide from linamarin is usually enzymatic and occurs when linamarin is exposed to linamarase, an enzyme normally expressed in the cell walls of cassava plants. Starch is the main component of cassava. Starch yields range from 20 to 35% and vary with genotype.

Processing and Uses

Cassava has to be prepared correctly to remove its toxicity. The traditional method used in West Africa is to peel the roots and put them into water for three days to ferment. Fermentation of cassava has been used to improve shelf-life and to alter aroma. In cassava fermented with added salt, 32 volatile compounds were quantified on day 50, including 9 alcohols and 6 aldehydes.

Cassava is predominantly consumed in boiled form, but substantial quantities are processed to extract cassava starch, called tapioca, which is used for food, animal feed, and industrial purposes. The root of the sweet variety is mild to the taste, like potatoes. Cassava can be made into a flour that is used in breads, cakes and cookies. In West Africa, garri is a flour, varying in texture from coarse to fine, made from fresh, starchy cassava root. Tapioca pearls are characteristically soft and chewy, with a prominent elastic texture and translucent appearance. Cassava is used in laundry products, especially as starch to stiffen shirts and other garments.