Location of xylanase and mannanase action in kraft fibres

The effects of the fibre surface on the action of xylanase and mannanase on pine and birch kraft pulps, and the location of enzymatic action in the fibres were studied using sequential enzymatic treatment and mechanical peeling. The enzymatic hydrolysis of the outer surface of the fibres was only partial in spite of the good accessibility of the surface material. The relatively high content of lignin in the surface material probably limited the action of the enzymes either physically or chemically. The intensities of the action of xylanase and mannanase. at the outer surfaces of the pulp fibres were, however, different. The location of the mannanase action was more concentrated on the surface of the pine fibres whereas the xylanase action was distributed almost uniformly between the surface and the inner cell walls of both pine and birch fibres. The difference in the location of action of the enzymes was probably due, at least in part, to their different molecular sizes and structures and, consequently, different mobilities in the fibres.