The physico-chemical characteristics identified at sweet cassava root, was: moistures (%),
fiber (%), protein (%), ash (%), total lipids (%), reducing sugars and total reducing sugars
(%); the sap extract from sweet cassava root was characterized by pH, soluble solids (%),
glucose and titratable acidity. This study used the yeast Saccharomyces cerevisiae PE-2. Was
realized 15 tests that followed the conditions determined by the experimental design of Box-
Behnken, with 3 independent variables: temperature (oC) (X1), pH (X2) and concentration of inoculum (g/L) (X3). The statistical analysis was performed with p>0,05. Through the
analysis of variance (ANOVA) was proposed a second order polynomial model to the alcohol
content (ºGl), and by analysis of response surfaces it was determined the optimum condition
to the fermentation of sap extract from sweet cassava root without addition of nutrients, on
original substrate concentration of it (6,46 g/L): 28ºC (temperature), 4,88 (pH) and 10 g/L
(inoculum concentration). Under these conditions a test was conducted, which aimed to raise
the curves of cell growth (yeast), CO2 production, consumption of sugars and ethanol
production, to better understand the process of fermentation broth of sweet cassava. Through
the cellular growth curve was determined the duration of the exponential phase, using the
method of linear regression; this step in this study occurred at different time intervals. The
value found to μm was 0,05 h-1.
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