Proposed Mechanism of the Enzymatic Bleaching of Kraft Pulp with Xylanases

Biobleaching Effects of Crude Xylanase from Streptomyces griseorubens LH-3 on Eucalyptus Kraft Pulp

“…Hydrolysis of xylan leads to the exposure of lignin within interior cellulose layers and accelerates the release of lignin during the subsequent chemical bleaching, thus reducing the damage to cellulose. Kantelinen et al (1993) investigated enzymatic bleaching and found that the average molecular mass of lignin extracted from enzymatically treated pulp was markedly higher than that of reference pulp with no enzymatic pretreatment. These results indicate that enzymatic hydrolysis of the xylan components of pulp can accelerate the release of lignin and thus reduce the damage to cellulose.…”

“…Viscosity reduction is not desirable because this property is related to the degree of cellulose polymerization and to paper strength (Paice et al 1988). Current studies on xylanase biobleaching have mainly focused on reduction of the consumption of bleaching chemicals (Garg et al 2011;Manimaran et al 2009;Khandeparkar and Bhosle 2007;Li et al 2005); very little attention has been given to the effects of xylanase on the yield and viscosity of pulp (Kantelinen et al 1993;Xu et al 2013). In the present study, a fermentation of S. griseorubens LH-3 was conducted, the crude xylanase extract was prepared, and the enzymatic properties of the crude xylanase were studied.…”

Bioprocessing of Agricultural Residuals for the Optimum Production of Extracellular Xylanase by Aspergillus brasiliensis in Solid State Fermentation (SsF)

“…This allows easy bleaching process of the pulp and hence, enhancing better brightness of paper [1,2]. Additionally, the initiative towards a greener environment is attained using xylanase where the usage of the costly bleaching chemicals that are potentially causing severe adverse effect to the environment was reduced [3]. There are several crucial fermentation parameters used to elucidate and optimise the production of xylanase including carbon and nitrogen source and their concentrations, initial medium pH, incubation temperature and agitation speed.…”

Adding Value Prior to Pulping: Bioproducts from Hemicellulose

“…The initial model proposed suggested that xylanases attack and hydrolyze mainly xylan redeposited on the fiber surface thereby enabling the bleaching chemicals a better and smoother access to residual lignin (Kantelinen et al, 1993). During kraft pulping, pulp xylan is first solubilized and later on part of it is redeposited back onto the pulp fibres.…”