Integrated microwave-assisted acetic acid pretreatment and endoglucanase-xylanase hydrolysis for nanocrystalline cellulose preparation.

Abstract

This study presents a high-efficiency extraction strategy for nanocrystalline cellulose (NCC) from tangerine peel as a model lignocellulosic biomass, using sequential microwave (MW)-assisted acetic acid (AA) pretreatment and dual-enzyme (endoglucanase and xylanase) hydrolysis. MW-assisted AA pretreatment (50 % AA, 100 °C, 10 min) achieves rapid volumetric heating and enhanced solvent penetration, and selective removal of hemicellulose, lignin and pectin components, while preserving crystalline cellulose domains, generating a highly accessible substrate for enzymatic processing. Subsequent hydrolysis with endoglucanase and xylanase (25 U/g substrate (TP-CFs) for endoglucanase and 50 U/g substrate (TP-CFs) for xylanase, 50 °C, 5 h, pH 4.8) depolymerizes amorphous cellulose regions and residual hemicellulosic barriers under mild conditions, resulting in NCC with uniform nano-fibrillar morphology (length 603.48 nm, diameter 9.23 nm, aspect ratio 65.36), high crystallinity (64.35 %), enhanced thermal stability (T_max 338.9 °C), colloidal stability (-30.2 mV) and high production yield (70.8 %). The MW-AA and dual-enzyme platform reduces chemical usage, lowers energy demand and enables selective biomass fractionation, establishing a simple, scalable and environmentally friendly pathway for high-performance nanocellulose preparation. • Microwave-assisted acetic acid pretreatment promotes rapid, selective biomass fractionation and cellulose preservation • Dual endoglucanase-xylanase synergy drives efficient amorphous cellulose removal under mild reaction conditions • The hybrid platform delivers high-yield nanocellulose production and structural integrity.