(Lead article from newsletter - TBGS - Spring 2005)

FOOD POISONING KILLS 30 KIDS IN RP

105 hospitalized; tainted cassava cake is blamed.
(Headline in The Filipino Express, issue of March 14-20)

(1) "What on earth is cassava ?" we were asked, and
(2) "How could something so tragic occur ?

This is about a major food source In the tropics and sub-tropics, consumed by more than 500 million people worldwide. Brazil produces about 25 million tons/year, and it's "very big" in Africa, Asia, and India --- a staple in place of rice.

Cassava aka Tapioca,etc.

Cassava species belong to Euforbiacea, genus Manihot. M.utilissima Pohl, M.esculenta Crantz, are among the bitter species, the tubers from which we derive Tapioca. Others, such as M.palmata aipi, eaten as a table vegetable, are the sweet cassavas.

Here's how it is consumed
biscuits (comb. w/wheat, soy ... whatnot) - breads - cakes, sipipa - cakes, spicy - chips - dumplings - grist - macaroni - meal - pancakes -pearl fancies - puddings - sour starch (for fast foods), a thickening agent in liquid foods... not to forget, intoxicating drinks, i.e., casiri & cassareep...

Here's how it is processed

baked - boiled - chipped - fermented - fried - grated - ground - milled - peeled - pounded - pressed - shredded - stacked - steamed - soaked - sun-dried - washed - and even winnowed, plus combinations of the above, and either wet or dried --- or, eaten raw.

The roots contain 7 - 12% protein, trace amounts of fats, and about 35% total carbo-hydrates including starch grains that make up 20 to 25% of the tuber. The rougher processing treatments rupture the cell walls, and allow the moist starches to be collected. [So far, so good.]

Also present in the tuber are two cyanide compounds and enzymes capable of breaking them down. Separated by the substrate, they remain independent of one another - and do not interact. But rupturing the cell walls brings them together, freeing up HCN to be vented into the air, or to be carried away in water.

Many plant species contain poisons; they often serve as part of the defense mechanisms against animals, birds, insects, microorganisms... Cyanides are not uncommon: found in leaves, seeds, pits and bark of plum, apricot, cherry, peach, nectarine, almond kernels, apple, and pear; in sweet potato, yam, maize, bamboo, sugar cane, peas, lemons, limes, and beans -including lima beans (Phaseolus l0unatus).

Boiling lima beans in an uncovered pot releases the hydrogen cyanide gases and renders them safe... Although our systems can "handle" small quantities of cyanides, larger amounts "may quickly result in anxiety, loss of balance, vomiting, breathing difficulty, kidney failure, high blood pressure, increased heart rate, and if treatment is not begun, may lead to convulsions, coma, and death."
www.naturallyhealthypet.com/plant_toxicology.htm
www.connovation.co.nz/assets/Documents/CYANIDE%20Environmental_1_.pdf

What Went Wrong ??? To Set The Scene ---

It was morning recess time. The 1st, 2nd & 3rd graders took off for the vendors outside to buy a favorite snack - deep-fried, caramelized cassava balls (locally called maruya.) Some took only two bites "because they tasted bitter and the effects were felt 5-10 minutes later" with dizziness, stomach pains, vomiting, diarrhea... By the time they could be taken to hospitals, some 40-odd miles away, many died.

Insisting nothing was wrong with them, one of the women vendors demonstrated by eating her own leftovers, and was also taken ill, and taken away in critical condition.

Enzymes in cassava act to break down Linamarin, a cyanide compound, releasing the HCN. Its level in the tubers of different species varies widely from ---:
(sweet) those with the smallest amounts, to
(bitter) those with the highest amounts, and -bitter having as much as 200 times the sweet.

Although we can de-toxify and excrete sublethal quantities, the frequent eating of inadequately processed cassava can bring on a condition of chonic toxicity that causes or enlarges upon a number of serious ailments.

Since cyanogenic levels are significantly reduced to zero or near zero by the proper, processing methods - it follows that that doesn't appear to have happened in this case. Sweet tubers and bitter tubers look alike. Possibly, they fried a very bitter, high content variety. Eaten raw or near raw, the human digestive system will convert part of the Linamarin into cyanide. Two cassava roots may contain enough to be fatal. With cyanides, you need a quantity less than half.the size of an aspirin.

It seems we must remind ourselves from time to time to "suspect" the contents of "natural" or improperly cooked. foods... This was a tragic reminder. //ss

www.ct.ilw.agrl.ethz.ch/chem/heuberger/ETHZILWFOODCHEMISTRY,HEAD
http://food.oregonstate.edu/ref/culture/africa_niba.html
http://www.filipinoexpress.com/19/11_news.html
http://www.cnn.com/2005/WORLD/asiapcf/03/09/mass.poisoning/

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