I. Main Processing Flow

II. Process Description and Technical Points

(1) Peeling

Due to the high content of cyanogenic glycosides in the edible cassava skin layer (which refers to the phloem of the root in botanical structure), it is necessary to peel off the skin to avoid the production of toxic cyanide (CN-) from the hydrolysis of the residual cyanogenic glycosides after processing. Manual peeling or mechanical peeling can be used in the processing of regular edible cassava flour.

(2) Chopping/Slicing

Since cassava tubers are quite hard, in order to make the tubers easier to dry, the surface area of the tubers can be increased by chopping or slicing, which facilitates the evaporation of moisture during the drying process and reduces drying costs. Normally, chopping into fries of 0.5 cm in width/thickness or slices of 0.3 cm thickness is appropriate.

(3) Drying

Drying is one of the key processes in the processing of edible cassava flour. It is recommended to use heat pump closed-loop drying at a condition of 55-60℃ to prevent the starch in the tubers from gelatinizing. Heat pump drying saves 30-50% more energy than traditional hot air circulation drying.

(4) Milling

Use a hammer or shear-type mill for milling. The mill comes with a 20-40 mesh screen, and a too fine screen can easily cause clogging and heat buildup during milling, leading to starch gelatinization and lump formation.

(5) Sieving

In order to improve the texture of edible cassava flour, it needs to be sieved with a 60-100 mesh. The flour that does not pass through the sieve is further milled.

(6) Bagging

Edible cassava flour is highly hygroscopic. It is recommended to use a double-layer waterproof sealed bag for packaging promptly after the flour has been sieved.

For more information, please contact WFP China COE (wfpcn.coe@wfp.org)