Fig. 6

Plots of predicted versus reference values of chemical components and theoretical ethanol yield. Soluble sugar (a), cellulose (b), hemicellulose (c), lignin (d), ash (e), and theoretical ethanol yield (f) for the external validation subsets based on partial-optimized partial least squares calibration models. The \(R_{\text{V}}^{2}\) represents the square of the correlation coefficients of the external validation subsets