Effect of processing on quality of cassava flour in Rwanda: a case study of Kamonyi and Ruhango districts

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Sokoine University of Agriculture


Consumption of cassava products, which linked to diseases such as Konzo. The need to study the effect of processing methods on the quality of cassava flour in Kamonyi and Ruhango was necessary. A survey was conducted to identify processing methods. Flours from locally processed cassava and modem industries were screened for nutrients, cyanogenic potential, physico chemical and microbiological quality using official methods of analysis. The survey results revealed that cassava was processed by fermenting them by submerging peeled whole roots(local 1) or pieces (modem 1) in tanks or wetland (unpeeled roots, local 2) or by grating (modem 2). They also showed that fermentation effluent water was often reused for next batches. The analytical results showed that the cyanogenic potential from the processing methods ranged between 0 and 10 ppm, which was within the EAC recommendations (lOppm). Cassava flour from chips processed by Modem 1 and 2 had moisture content within the EAC recommendation of 13% (max). For processing methods Local 1 and Local 2, results showed high moisture content (19.3 - 26.2%) above that recommended by EAC. This explains the high microbial count (bacteria, 2.6 - 5.5 log CFU/g and coliforms, 2 - >1600 MPN/g) but fungal count was within the WFP recommend value of 51og CFU/g. The pH (6.19 - 7.49) and TTA (0 - 1.05%) for both methods (local and modem) indicated microbial activity taking place. The cyanide in cassava flour was within the permissible limit of less than 10 ppm, thus not a health problem. The microbiological quality of cassava flour in studied districts confirmed that the processing methods used did not follow the good hygienic practices and thus affecting safety of cassava flour. Use of tap water and modem driers for processing and close monitoring to ensure strict compliance are recommended.


MSc.Dissertation in Food Science


Cassava products, Cassava flour, Konzo diseases, Rwanda, Kamonyi-Ruhango Districts