Optimization of process conditions for cassava (Manihot esculenta) lafun production

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 59o
C.
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 41o
C; 2.50 l, 48 h and 35o
C; and 2.50 l, 72 h and 41o
C, respectively.