2.1.2. Experimental design
The Box-Behnken method has been selected for the optimization
of three variables (acid concentration (% v/v), temperature (C)
and time (min)). The variables, factors and level are referenced in
Table 2. For the three variables, 17 runs were conducted to produce
fermentable sugar which is referenced in Table 3. The design
summary for acid hydrolysis with three levels and three factors is
presented in Table 4. The central composite design has mostly been
used for fitting the second-order model. The second-order model is
defined as follows to facilitate calculations: