more than you wanted to know about cassava

ok, so cassava is a tuberous root, similar to the potato that is the staple crop for much of sub-saharan africa. its originally from south america, but has been cultivated in africa for hundreds of years and takes varying shapes as a foodstuff (including tapioca pudding) but typically ground into a dough and eaten as a filler, often served with stew or meat.

positives:

• it's drought tolerant
• can grow underground for 20 months
• very hardy
• has easily available starch

sounds good, right?

bummers:

• it rots quickly after harvesting
• won't save in the raw form
• contains naturally occurring cyanide

worse, cyanide concentrations increase in times of drought when, coincidentally, people are hungriest. so you must prepare it by soaking or fermentation, which removes the cyanide sufficiently to consume. this is all well and good on a small scale when you are consuming household size amounts but as a result of the efforts to improve food security, the village has formed an industrial scale processing plant which means industrial scale cyanide waste water. that's where we come in.


here's the processing plant

and here's the problem: what to do with toxic waste water?currently they are diverting it into a 15 meter deep collection well which will fill and they'll dig another, i.e. bad idea.

max, a med student from umass, looks pensively over the situation

ok, here's the process;
cassava harvested once from underground

a short shelf life means it needs to be close to end consumer

weekly, a truck collects cassava from local farmers and brings it to the processing facility


shares are weighed and farmers are paid 50 rwandan francs/kilo (10 cents USD)

sometimes goofy white people get in the way and waste your time by measuring and weighing stuff

women peel the cassava (imyambati in kinyarwanda) for 2.5 Rwfrancs/kilo


sometimes goofy white people get in the way and waste your time by measuring and weighing stuff again

sometimes goofy white people try to peel cassava and cut their fingers off

peeled cassava are washed in a tank to remove dirt and debris

sometimes dorky white people sample wash water for cyanide

clean fruit is loaded into the rasper behind the men and chipped into flakes

this is on the other side of the wall from the rasper. the square opening in the back wall is the outlet.

the chipped cassava is bagged and set into these soak tanks that draw out cyanide for 2-3 days. the capacity of these tanks are ~3 metric tons apiece.

pressing the soaking bags to remove excess water

normally cassava is spread on the ground or on tarps to sun dry. this has become the hitch in the process because of the time and space needed.

the facility has built greenhouses and drying racks to improve efficiency...


unfortunately the are made of impermeable plastic (unicef tarps) which doesn't allow air to circulate
the flakes must be turned and raked to improve air flow

flaked, sun-dried cassava

they allowed us some space to experiment with a new design made of poly "burlap" sacks...

sometimes dumb white people tear up a perfectly good drying rack and mess up a full day's work

happy workers covered in cassava dust at the mill

some white guy pointing out the obvious

varying sizes of flour

sometimes the great white nerd (me) tries to help clean the grinding mill

flour is bagged into 5 kilo bags and sold locally and in the capital, kigali, for 2000 Rwfrancs (2USD)


i hope you weren't too bored with that intro. i will be putting together a video of what we are doing and some projects. thanks for reading!!!