Cassava is an excellent starch for the tropical diet. And making homemade cassava flour is a great way to store your crop with minimal space. My husband has been trying to grow cassava on our tropical fruit farm on Big Island for 6 years. But, every time the cassava is ready to harvest the wild boars come dig it up and eat it. Finally, we started planting cassava in our large garden protected by electric netting. This is the first year we have had multiple harvests. It takes a minimum of 6-7 months for smaller roots and for some varieties up to 24 months to harvest. Cassava grows readily from cuttings. If you are in Hawaiʻi and are interested in cassava cuttings, contact me or visit our farm website ainaexotics.com.
How to reduce cyanide in raw cassava
Most how-to recipes for homemade cassava flour tell you to cook cassava pieces first and then grate them. I think this is quite silly. The authors may be worried about cyanogenic compounds (cyanide) in cassava. But if you ever cooked cassava you know it becomes starchy and sticky, and very hard to grate.
There several methods to reduce the cyanogenic compounds (cyanide) in cassava. If you eat these compounds raw they have a toxic effect. There are also varieties with low cyanogenic compounds. One method of reduction is cooking by boiling, steaming or baking. Soaking the cassava in water also reduces the cyanide. Industrial producers of cassava flour rely on the drying and milling process to reduce cyanide levels. In the more traditional version of cassava flour, they ferment the grated cassava to reduce it’s toxicity, and then dry.
Gari – a fermented cassava flour / granules
There is similar product to milled cassava flour, called Gari. Gari is staple in West Africa, in particular Nigeria which is the leading industrial producer of cassava flour. There, they grate Gari and ferment it for 3-7 days. Then they roast it and sift it into cassava granules. Their goal is to achieve a slightly fermented and sour taste while assuring that the cyanogenic compounds are decreased. West Africans use Gari as a side dish, a thickener, and as an ingredient on other dishes, desserts and more.
My method for making homemade cassava flour
This tutorial gives you a few extra steps to reduce the cyanogenic compounds in case you would like to be on the safer side. These steps are optional but if you have the time, they can enhance the quality of the flour. Basically, I soak the peeled cassava in water and hang/slightly fermenting it overnight or up to 24 hours before drying. As I am writing this I have 13 pounds of shredded cassava that have been hanging from my bathtub curtain rod for 24 hours. I actually find the smell really pleasing, sort of nutty.
This is basically a 2-3 day process depending on how much cassava you are processing, if you decide to ferment (and length of ferment) and what time in the day you start. I started with probably 20 pounds of freshly harvested yucca. It took me about and 1 1/2 to peel, core and grate the cassava. Then I hung the cassava in a mesh bag for 24 hours. My drying process took 8-10 hours and by that time it was bed time. Consequently, I kept the pilot light of my oven on to prevent it from re-hydrating or molding, and I “milled” it the next day.
Here is a few more tips:
You are better off processing cassava fresh, within 2-3 days of harvesting. I processed some of the left over cassava on day 4 and there was noticeable deterioration of the root, it started to become streaked, sort of blue and in some cases there was evidence of rot. Also, the ends of the roots which weren’t tapered and clean cut had started to mold.
You can peel and wash and leave in soaked water for a few days in the fridge if you are not ready to deal with the grating or processing.
The knife pictured below is hardly big enough to process really thick roots. For those I use a really heavy duty butchers knife / cleaver.
How to make homemade cassava flour
- about 20 pounds Freshly harvested cassava root
Peel, wash and core the cassava
- With a sharp butchers knife, cut the cassava into pieces about 2 inches long (this will make it easier to peel and core. If your cassava if freshly harvested you can wash the cassava before you cut it to avoid dirt all over your counter, but I usually skip this step and wash it after peeling.
- Using a smaller knife like a paring knife, make a deep incision in the thick peel of the piece, working around the cassava remove the peel (it's pretty easy).
- Wash the cassava and place it in a bowl/pot of cool water. This will aid in reducing the toxic compounds, while you prepare the remaining cassava
- If your cassava is larger than 1 ½ diameter it will probably have a woody core. To ensure your end product is digestable, it is best to take action to remove this. Simply cut the 2 inch piece into 4 pieces and slice a "triangle" off of each where you see the cassava sort of change color and texture, almost like a ring of a tree inside.
Grate and ferment the cassava
- Grate your cassava in a food processor with the grater attachment.
- Is you choose to, you can ferment the cassava at this stage to get a slightly nutty and more pronounced flavor. Using a mesh bag, hang the cassava for 5 – 24 hours, moving it around every once in a while to aerate the surface areas.
- If you are using your oven, set it to the lowest temperature (mine goes to 170° F) I Spread the cassava out in a thin layer on baking sheets and prop a spoon in the door to let air escape (or use lever that is meant for broil). Depending on how thin the layer is you may need to mix the shreds every few hours. Should be done in 5-10 hours depending on thickness*
- If you are using a dehydrator, place on trays in a thin layer and dehydrate on the highest setting ~159° F. For even results you should rotate the trays 1-2 times. The top trays dry quicker than the bottom.**
Mill the cassava shreds
- If you have a small batch you can try putting directly into your high speed blender, pulse and shake it up every few pulses to achieve an even texture
- For larger batches I recommend, using your food processor to chop the shreds into finer particles and then process in your blender.
- To mill in your blender, fill the blender 1/3 full and pulse the first few times before putting on high speed for about 30 seconds. Make sure to have your counters clean without clutter because the flour particles will get everywhere when you open the blender.
- At this stage there still may be gritter particles. You can sift them out now or sift them out according to the recipe you use. I've made bread with 1/4 homemade cassava flour and have used the flour in veggie burgers and never noticed the gritty parts. But If I was making something from just the flour I would probably sift out the grits and re-blend. For best result, in a tropical climate store in airtight bag in the fridge or freezer.