Abstract

Optimization of cassava (Manihot esculenta, NR8082 clone) lafun production and evaluation was carried out using response surface methodology. The selected experimental design had three variables and five levels referred to as central composite design. Process variables were inoculum volume, fermentation time and drying temperature. Inoculum volumes were 1.50, 2.00, 2.50, 3.00 and 3.50 l. Fermentation times were 24, 36, 48, 60 and 72 h while drying temperatures were 35, 41, 47, 53 and 59^oC. Response surface data on lafun yields, colour index and cyanogenic potentials were analyzed in a regression model while three-dimensional response surface plots were made. Effects of process variables on lafun parameters varied depending on which response was analyzed. Maximum and minimum yields were 82.68 and 66.68% for lafun flour and 68.24 and 56.20% for lafun starch, respectively. Photometric colour index ranged from 10.03 to 30.51 while cyanogenic potentials of the flour ranged from 1.88 to 5.31 mg HCN/kg and that of the paste from 0.93 to 3.11 mg HCN/kg. Models developed by response surface analysis for these responses were significant at low (1 to 5%) levels of probabilities and could be explained by regression coefficients in the models. Variabilities explained by the models were low for lafun flour yield (R² = 0.3188) but high for photometric colour index (R² = 0.8098). Optimum process conditions obtained for starch yield, photometric colour index and cyanide reduction were 2.0 l, 36 h and 41^oC; 2.50 l, 48 h and 35^oC; and 2.50 l, 72 h and 41^oC, respectively.

Key words: Cassava, lafun, fufu, hydrogen cyanide, optimization, response surface

Methodology