ABSTRACT

The effect of fermentation time on hydrogen cyanide contents of three varieties (TMS91934, TMS30572 and NR87184) of bitter cassava was studied in grated and fermented cassava for a period of five days to determine the optimum number of days of fermentation for best quality mash and garri. Standard methods were used in studying the effect of duration of fermentation on Hydrogen cyanide (HCN) and Moisture content. The proximate composition of the garri from the 5" day of fermentation was also determined. The results showed that the cyanide content of the cassava on the zero day for the peel, liquor and mash ranges from 49.10-56.64mg/kg, 21,45-31.57 mg/kg and 4.14-18.04 mg/kg respectively. The cyanide contents decreased significantly {p<0.05) with the length of fermentation period of the grated cassava mash from I st to 5th days. The values range from 5.59-10.03 mg/kg, 4.99-5.92 mg/kg, 3.00-4.85 mg/kg, 3.59-5.38 mg/kg and 2.98-3.25mg/kg respectively. Though there was a decrease in cyanide concentrations between the 4th and 5th days, they were not significantly (p>0.05) different in the values. The values of the cyanide reduced significantly as the cassava was toasted from 1" day to 5 day. The value ranges from 7.32-15.42 mg/kg, 7.06-7.73 mg/kg, 4.45-6.54 mg/kg, 4.44-5.42 mg/kg, and 3.25-4.79 mg/kg respectively. The result of the effect of fermentation on the moisture content of the mashed cassava showed that the moisture content decreased significantly from the 1' to the 5" day as the value ranges from 43.25-49.19%, 41.90-47.50%, 43.30-45.95%, 40.48-44.10% and 36.15-40.28% respectively. The moisture content of the toasted garri from the I st to the 5" day range from 11.62-15.44%, 5.16-11.14%, 5.70-6.59%, '4.50-7.46% and 4.60- 6.69% respectively. The results of the proximate content of the garri from the three cassava varieties for the 5" day fermentation which had the least cyanide content ranges from 10.54-11.38%, 85.95-89.21%, 1.94-2.29%, 0.58-0.70%, 0.56-0.64%, 2.95-3 .22, and 81.63-63.36% for the moisture, dry matter, Ash, crude fibre, Ether extract, crude protein and carbohydrate respectively. These values indicated that about 50% of HCN are contained in the peel. It is also observed that fermentation time also affected the moisture content of mash and garri which decreased as fermentation time increased.