The equations of the empirical model adjusted to the ethanol
yield (Y2), concentration of residual sugar (RS) and ethanol productivity
(P) as a function of significant variables are presented in
Eqs. (4)–(6), respectively. The correlation coefficients (R2) obtained
after adjustment were 0.992 for the ethanol yield, 0.995 for the
concentration of residual sugar and 0.992 for the ethanol productivity,
indicating that the proposed empirical equations faithfully
reproduces the results obtained experimentally.