Effect of commercial cellulases and refining on kraft pulp properties: Correlations between treatment impacts and enzymatic activity components

•Xylanase activity has a positive impact on drainage property of kraft pulp.•Ion chromatography was used to quantify the carbohydrates concentration.•Physical properties of handsheets were correlated with enzyme activity.•The balance between cellulase and xylanase activity is important for refining.•Enzyme treatment allowed to decrease refining intensity by about 50%. The importance of enzymes as biotechnological catalysts for paper industry is now recognized. In this study, five cellulase formulations were used for fibre modification. The number of PFI revolutions decreased by about 50% while achieving the same freeness value (decrease in CSF by 200mL) with the enzymatic pretreatment. The physical properties of handsheets were modified after enzymatic pretreatment followed by PFI refining. A slight decrease in tear strength was observed with enzymes C1 and C4 at pH 7 while the most decrease in tear was observed after C2, C3, C5 treatments. C1 and C4 which had xylanase activity improved paper properties, while other enzymes had a negative impact. Therefore, the intricate balance between cellulolytic and hemicellulolytic activity is the key to optimizing biorefining and paper properties. It was also observed that C1 impact was pH dependent, which supports the importance of pH in developing an enzymatic strategy for refining energy reduction.