Saccharification and structural changes in Areca catechu husk fiber

Abstract

Areca nut husk (ANH) holds promise as a viable biomass source for xylose production. Xylose is a precursor for various biochemicals. However, the recalcitrant nature of ANH makes saccharification more complex. To address this, lime and acid pretreatments were carried out to enhance the susceptibility of biomass to saccharification. Before this, a compositional analysis was conducted to determine the initial constituents of the feedstock. Saccharification was conducted under the following conditions: 2% (wV⁻¹) substrate loading, 100 rpm agitation, and 30 °C hydrolysis temperature for 12 h hydrolysis time at pH 4.5 to 5.0. However, parameters like xylanase enzyme loading were varied to enhance the saccharification of the ANH. The results demonstrated that acid-treated husk (ATH), lime-treated husk (LTH), and raw husk (RH) achieved the highest yield (gg⁻¹) of reducing sugar, approximately 90, 83, and 15%, respectively, at an enzyme loading of 15.0 IUg⁻¹. Various analytical techniques, including Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), zeta potential, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) were used to examine structural changes in the native, pretreated, and saccharified residues of ANH. The analysis revealed that a significant amount of partial crystalline and amorphous cellulose in the ANH biomass was hydrolyzed during the saccharification process. However, saccharification also led to the removal of amorphous substances, disruption of the crystalline structure, and conversion of crystalline regions into amorphous domains.