Global Forum on Food Security and Nutrition (FSN Forum)

Thanks for the interesting example of the time taken in the preparation of cassava leaves. In the case of cassava leaves, grinding has a purpose, as it removes cyanogens, which are often present in high concentrations.

The grinding thus prevents cyanide poisoning.

A recent report of a simpler preparation method also refers to the literature on nutrient content and preparation of cassava leaves:

Bradbury JH, Denton IC (2011) Mild methods of processing cassava leaves to remove cyanogens and conserve key nutrients. Food Chemistry 127: 1755-9.

Cassava roots may also contain high concentrations of cyanogens. 

For both cassava roots and leaves, removal of cyanogens is an important part of food preparation.