Xylooligosaccharides production by acid hydrolysis of an alkaline extraction filtrate from Eucalyptus globulus bleached kraft pulp

•Bleached Kraft Pulp from Eucalyptus globulus shows potential for XOS production.•Alkaline pretreatment costs can be reduced by UF of the xylan-rich filtrate.•30 % conversion of xylan to XOS was obtained by an alkaline filtrate acid hydrolysis.•In terms of XOS, a majority of X2 and X3 was produced (> 40 %).