Elucidating the Correlation of Lignocellulosic Compositions and Physicochemical Alterations in Oil Palm (Elaeis guineensis) Biomass on Enzymatic Saccharification Yield

This study investigates the correlation between both the chemical compositions and physicochemical properties of pretreated oil palm empty fruit bunch (OPEFB) fibre and their enzymatic saccharification/total glucose yield (TGY). Twenty OPEFB samples, pretreated with various aqueous pretreatments, with diverse cellulose (25.63–44.23%), hemicellulose (0.01–42.49%), and lignin (3.7–47.1%) levels, were examined for their correlation with TGY (8.5–40%). The quadratic regression model was verified significant (p-value = 0.0006, R² = 0.8006). It was found that the pre-refined OPEFB experienced greater cellulose loss (35%) compared to unrefined ones (9%), adversely affecting TGY. Among physicochemical properties analysed using SEM, FTIR, XRD, Py-GCMS, and XPS, only crystallinity index (CrI) was significantly correlated with TGY based on theoretical glucose concentration (TGC) (R² = 0.77, 0.91). Other characteristics (morphology, functional groups, crystallite size, S/G ratio, and O/C ratio) exhibited no significant correlation to saccharification efficiency, exhibiting random trends (R² < 0.5). OPEFB fibres with CrI of 30–40 could achieve 100% TGY based on TGC. In conclusion, regardless of pretreatments, chemical compositions predominantly affected TGY in the enzymatic saccharification of biomass. Among commonly used physicochemical analytical methods, CrI is most significant in this evaluation and OPEFB should be unrefined before treatment to avoid cellulose loss.