Integration of Multiple Fundamental Instrumental Analyses to Understand the Key Factors for Enhancing Enzymatic Saccharification of Oil Palm (Elaeis guineensis) Empty Fruit Bunch by Aqueous Pretreatments

Abstract

Simple aqueous pretreatments were performed on oil palm empty fruit bunch (OPEFB) to enhance its enzymatic digestibility by the cellulolytic enzyme. Autohydrolysis, acid and alkaline pretreatments were conducted at appropriate temperatures for 45 minutes with a solid: liquor ratio of 1:7. The refined pretreated OPEFBs were enzymatically saccharified at a fixed condition of 50°C, pH 4.8 for 48 hours. Besides chemical composition analysis, various changes in biomass during pretreatments were also evaluated using the fundamental instrumental analyses namely HPLC, FTIR, SEM, XRD, Py-GCMS and XPS. Autohydrolysed biomass achieved the maximum (> 99.9%) enzymatic saccharification/total glucose yield (TGY), attributed to 77% hemicellulose and 24% lignin removals, with only 16% cellulose loss. The crystallinity index was significantly correlated with TGY, but morphological analysis, S/G ratio of lignin, and O/C ratio were irrelevant. The key TGY-enhancing factors of pretreatment were unable to be identified by any single instrumental analysis. Determining the chemical composition of the biomass remains the primary fundamental analysis to understand the requirement for improving enzymatic yield.