Cassava or kamoteng kahoy is popularly known to have poisonous cyanide. It is poisonous if sufficient amount is inhaled or adequate quantity is consumed.
A student was selling cassava suman in between classes to cover her tuition fees, daily allowance and other school needs. Selling in school premises without administrative permission is illegal. I hope this instance is an exception.
A short interview:
What was that?
It was suman made of cassava. A mixture of grated cassava and sugar. It was wrapped in banana leaves and boiled.
Was that soft or hard? If the kamoteng kahoy used was matured, then the resulting product will be tougher than normal.
The texture was normal. Not too soft and not too hard.
Was that safe to consume? It might contain harmful cyanide enough to send me to hospital or even worse.
It was safe. We pressed out the juice thoroughly after grating, to remove any possible danger substance.
The popular way of removing or avoiding the harmful chemical are by harvesting young but plumb roots and by fermentation. Pressing out the liquid after grating is an addition to mentioned methods. It might not rid of cyanide completely but it will sure remove significant amounts.
How about the nutrients? Loss of juice sure took away nutrients.
Cassava is a rich source of carbohydrates, the energy giving carbs. The main reason why we are eating cassava is to get energy. Take a variety of nutritious foods like fruits and green leafy vegetables for a balance nourishment.
Cassava (Manihot esculenta) 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.
When I was in high school years. My mom and dad always plant cassava in our farm and sell it for a living. I love broiled and boiled cassava without knowing that the food I was eating contain cyanide.
Cyanide is a naturally occurring chemical, generally considered to be poisonous if consumed in large amounts.Exposure to high levels of cyanide for a short time harms the brain and heart and can even cause coma and death. Workers who inhaled low levels of hydrogen cyanide over a period of years had breathing difficulties, chest pain, vomiting, blood changes, headaches, and enlargement of the thyroid gland.
Cyanides are naturally present in plants. Amounts are usually low in the edible portion but are higher in cassava. Pits and seeds of common fruits, such as soursop, apricots, apples, and peaches, may have substantial amounts of cyanide.
Cassava roots and leaves cannot be consumed raw because they contain two cyanogenic glucosides, linamarin and lotaustralin. Cassava varieties are often categorized as either sweet or bitter. The sweet cultivars can produce as little as 20 milligrams of cyanide per kilogram of fresh roots, while bitter variety may produce 50 times as more, 1 g/kg. Cassavas grown during drought are especially high in these toxins. A 40 mg of pure cassava cyanogenic glucoside is sufficient to kill a cow.
A safe processing method is to mix the cassava flour with water to form a thick paste and then let it stand in shade for five hours in a thin layer spread in tray. Through this method, 5/6 of the cyanogenic glycosides are broken down by the linamarase; the resulting hydrogen cyanide escapes to the atmosphere, making the flour safe for consumption .The traditional method used in West Africa is to peel the roots and put them into water for 3 days to ferment.
More info at ATSDR .