ENZYMATIC MODIFICATION OF RADIATA PINE KRAFT FIBER AND HANDSHEET PROPERTIES

The response of unbleached and bleached radiata pine slabwood and thin nings kraft fibres to treatment with different purified enzymes are qu antified and assessed. The enzymes were two xylanases, a cellobiohydro lase, and three endoglucanases. Unbleached slabwood fibres of high coa rseness with thick walls show the greatest response to enzyme treatmen t. Corresponding fibre and handsheet property differences are smaller for bleached than for unbleached slabwood pulp. Thus, the additional c arbohydrate material and/or residual lignin present in the robust fibr es of unbleached slabwood pulp must interact in some way during or aft er enzyme treatment. Some enzyme treatment effects on the unbleached s labwood pulp are - Xylanase treated fibres retain their intrinsic stre ngth but can be stiffer with surfaces of lower water affinity and bond ing potential compared to untreated fibres. Handsheet properties are m odified with tear index being selectively increased. Cellobiohydrolase treated fibres increase in size and stiffness but retain their intrin sic strength and bonding potential compared to untreated fibres Handsh eet properties are modified but tear index is not selectively increase d. Endoglucanase treated fibres (100 mu g/g) are degraded with fibre a nd handsheet strengths lowered. Extents of degradation are different f or the three endoglucanases.