Effect of grating, chipping, dry fermentation and sun drying on cyanide level of cassava in Tongwe village.
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Date
2009
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Sokoine University of Agriculture
Abstract
This study was conducted to evaluate effectiveness in cyanide reduction by four different methods of processing cassava roots, two traditional (dry fermentation and direct sun drying) and two improved methods (grating and chipping) and also assess losses due to cassava processing in Tongwe village (Muheza District). Presence of mycotoxin-producing organisms in fermented cassava flour was examined. Cyanogens were determined using the AOAC alkaline titration method. The microbial growth was done on plate using Sabouraud’s Dextrose Agar (SDA). The cyanide level, in the processed cassava differed significantly (p<0.05). Improved methods were more effective than traditional. The mean cyanide was; 6.79, 7.96, 8.96 and 9.90 mg HCN/kg DWB for grating, chipping, dry fermentation and direct sun drying, respectively. Identification of mould revealed the absence of mycotoxin producing organisms and therefore ruled out the possibility of presence of mycotoxins in the dry fermented cassava flours collected from 60 households in Tongwe and 10 samples prepared in Tongwe cassava processing unit. Losses due to
processing in all four methods were determined by calculating the difference between peeled fresh cassava weight and the weight of flour produced after processing. Results showed significant differences (p<0.05) between the traditional and improved methods studied. The mean percentage losses were; 67.28, 69.73, 51.83 and 54.14 for grating, chipping, dry fermentation and direct sun drying, respectively. Sensory evaluation done at SUA and Tongwe showed significant differences (p<0.05) in preferences between the stiff porridge prepared using flour from all four methods of processing cassava, the most preferred product being ugali from chipped cassava flour. This experiment has indicated that improved methods are more effective in cyanide reduction than traditional ones. However, traditional methods were more economical in processing losses and that there were no mycotoxin-producing organisms in fermented cassava flour. Both methods produce acceptable products worth encouraging if losses are minimized.
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Keywords
Tongwe village., Grating, Chipping, Fermentation, Cassava