Dear Reader,

Some persons are concerned about the toxicity of cassava, especially those who have not been having it as a part of their regular intake. There are even concerns about animal consumption of the product.

Cassava has the potentially toxic cyanogenic glucosides linamarin and a small amount of lotaustralin present in its tissues. Linamarin is chemically similar to glucose but with cyanide attached. Cyanogenic glucosides are toxic because they release hydrogen cyanide as a result of enzymatic hydrolysis following maceration of the plant tissue. Only about 20 per cent of hydrogen cyanide released from linamarin in the gastrointestinal tract is absorbed.

There are two varieties of cassava - the sweet and the bitter variety. Most references show that the bitter type has a higher level of hydrogen cyanide. Values vary in both varieties from 15 to 400mg/kg fresh weight of hydrogen cyanide in the root of the cassava. The sweet variety has 15 to 50mg/kg. The sweet variety can be processed by peeling, then boiling, thus yielding a safe product.

The bitter variety needs more intensive processing and levels of up to 2000 mg/kg fresh weight of hydrogen cyanide has been reported. Grating and expelling the juice and also fermenting, a method which is used commercially ensures safety.

Safe levels are established for cyanide in foods by the FAO/WHO Codex Alimentarius Commission at 10 mg/kg dry weight and levels below 100 mg/kg dry weight are considered safe for foods such as chips and pellets and are accepted for import into the European Union for feeding livestock. We rely on regulatory bodies to ensure our safety. Individuals doing their own preparation should follow the stipulated guidelines according to the type of cassava to ensure safety.

Long-term toxicity

There are few reported controlled, long-term studies in laboratory animals on the toxicity of linamarin or hydrogen cyanide. However, adverse effects seen in humans from long-term consumption of cassava include neurological diseases.

I am sure that Jamaicans will continue to have a variety of staple foods including the cassava in their diets and safe methods will be employed for their preparation. I also imagine that the relevant authorities will do more education of our people as we seek to increase our intake of this staple,

Boiled and fried cassava

Bammies are made from cassava. - File

Dear Ms Brown,

I enjoyed your recent article on cassava. Although I was born and grew up in Jamaica, it was not until I was living here, in the United States of America, that I found out that some types of cassava were poisonous. In fact, I learnt of this on a television programme that showed some indigenous people in South America squeezing out the cyanide which they then used on arrows in their blow guns when they weat hunting.

I always liked cassava as a child but I used to wonder where 'tapioca' came from and in 1990, on a scuba dive trip to Fiji, I found the answer. The cassava is first boiled, dried and then fried. You would not believe just how light and nice the end product turns out.

We live in New Jersey, where cassava can be found peeled and frozen year round or it can be found fresh, although it is processed with wax to prevent shrinkage. Here, though, it is hardly ever called cassava but yucca, the Spanish name for it.

- Leighton in New Jersey

Dear Reader,

Tapioca, as you may have discovered, is the starch made from the cassava root. It is used in the food industry as a thickening agent and the tapioca pudding was once a popular childhood dish.

I have had sweet cassava prepared Cuban style and it was delicious, so I can imagine that the dish which you described must be quite delectable. Prices are also increasing here in Jamaica, but we are resilient and have the options of our local staples and the opportunities for doing more home gardening.

There is also a push by the government for more schools, homes and the community, in general, to do more planting of food crops. This Labour Day, May 23, the nation should be focusing on planting. The challenge will be great with the increase in fertiliser prices and the problem of irrigation for our farmers. We do need more economical options to solve these two problems.