Green production of prebiotic xylooligosaccharides via enzymatic hydrolysis from xylan black liquor of oil palm frond

Abstract

The black liquor generated from the alkaline pretreatment of lignocellulosic biomass is usually disposed of into wastewater, which could lead to environmental pollution. Alkaline black liquor (ALBL) contains a large amount of xylan with a small fraction of lignin, making it a promising raw material for the production of xylooligosaccharides (XOS). In this study, xylan was extracted from the ALBL generated upon treating the oil palm frond (OPF) with sodium hydroxide via two-stage precipitation for the separation of lignin and recovery of xylan. As a result, approximately 84.0% of xylan retrieved from the ALBL was recovered. Subsequently, enzymatic hydrolysis was optimized to recover the maximum amount of XOS from xylan. The results showed that enzymatic hydrolysis produced the highest XOS (62.5%) under optimal conditions of 50 °C, 4 U/mL xylanase, and 3% xylan loading for 48 h. The study provides insight for maximizing utilization of ALBL of OPF for future biorefinery economy.