Philosophical Vegan Forum

caLRo wrote:I don't like eating raisins by themselves

Konzo is an epidemic paralytic disease occurring among hunger-stricken rural populations in Africa where a diet dominated by insufficiently processed cassava results in simultaneous malnutrition and high dietary cyanide intake.

In the future there is likely to be an increase in cyanide poisoning and konzo amongst the poorest of the poor in tropical Africa because consumption of cassava is increasing, there is a lack of knowledge about cyanide poisoning and no experience of proper processing methods in new areas where cassava has not been grown before and droughts are increasing in frequency due to climate change. Konzo occurs during drought because the total cyaninde content of cassava roots increases greatly due to water stress and short-cut processing methods are used during food shortages. Adoption of the wetting method by rural women is an important tool to reverse these upward trends and help to eliminate cyanide poisoning and konzo.

How should Cassava be Processed to Render it Safe for Consumption?

Cassava contains more than one form of cyanogenic glycosides. Different varieties of cassava are generally classified into two main types: sweet cassava and bitter cassava. Sweet cassava roots contain less than 50 mg per kilogram hydrogen cyanide on fresh weight basis, whereas that of the bitter variety may contain up to 400 mg per kilogram.

Sweet cassava roots can generally be made safe to eat by peeling and thorough cooking. However, bitter cassava roots require more extensive processing. One of the traditional ways to prepare bitter cassava roots is by first peeling and grating the roots, and then prolonged soaking of the gratings in water to allow leaching and fermentation to take place, followed by thorough cooking to release the volatile hydrogen cyanide gas. Cutting the roots into small pieces, followed by soaking and boiling in water is particularly effective in reducing the cyanide content in cassava. Whilst fresh cassava requires traditional methods to reduce its toxicity, adequately processed cassava flour and cassava-based products have very low cyanide contents and are considered safe to use.

What Other Edible Plants Contain Cyanogenic Glycosides?

Bamboo shoot is a popular food item among Asian population. The cyanogenic glycoside present in bamboo shoot is decomposed quickly in boiling water. Other edible plants containing cyanogenic glycosides include kernels within the pits of some stone fruits (e.g. bitter apricot kernels), lima beans, etc.

Colorful lima beans, such as those popular in early Peru, can contain up to thirty times more cyanogens than the domesticated cultivars grown today. Eaten raw and in significant quantity, such a bean meal might just kill us off.

Luckily, we can beat out the belligerent lima bean by cooking it. Cooking turns cyanide-generating enzymes into impotent mush, rendering the beans both safe and recipe-ready.

In certain plant foods, including almonds, millet sprouts, lima beans, soy, spinach, bamboo shoots, and cassava roots (which are a major source of food in tropical countries), cyanides occur naturally as part of sugars or other naturally-occurring compounds. However, the edible parts of plants that are eaten in the United States, including tapioca which is made from cassava roots, contain relatively low amounts of cyanide.