A simplified two-level fractional factorial design method
was used for the initial test to find the effective test range of
the variables (extraction condition) which affected the
response (inulin extraction yield) and allowed the fitting
of a first-order model to the data. A 241 fractional factorial
design leading to 8 sets of experiments was used to verify
the most significant factors affecting the extraction of
inulin. The variables were coded according to the following
equation: