As with rice, processing fonio involves two successive operations:

• hulling, which removes the husks from paddy fonio (rough grain) to produce hulled grain (decorticated grain)
• whitening, which removes the bran (pericarp and germ) to produce whitened fonio

Flow diagram of fonio processing (© J-F Cruz, Cirad)

Laboratory trials at CIRAD (Montpellier) on different fonio varieties from Guinea with a moisture content of 11-12% showed that the husk and bran make up 23 and 9% of paddy grain respectively.

The potential processing yield when making whitened fonio from paddy fonio should theoretically be around 68%.