Effect of Treatment with Two Kinds of Laccases on Free Radical of Pinus kesiya var. langbianensis Sapwood

Fibreboard without formaldehyde will be manufactured by laccases treated wood fibre to eliminate the pollution of free formaldehyde in the wood-based panels. To obtain the optimum parameters of laccases treatment is fundamental to develop new environmentally friendly fibreboard. The woodflour of Pinus khasya var. langbianensis sapwood and two kinds of laccases (White-rot fungi, laccase Ⅰ; Aspergillus, laccase Ⅱ) were used. Laccase treatment of the sapwood in suspension were conducted under the following conditions: acidity from pH 2.0 to pH 6.0, temperature from 30℃ to 80℃, treatment time respectively for 1 h, 2 h, 3 h and laccase dosages 10 u/g,20 u/g,30 u/g. Free radicals of reactive oxygen species (ROS) were detected after reactions by Electron Spin Resonance (ESR). Compared with control, relative concentration of ROS increased remarkably after woodflour was treated with two kinds of laccases. The optimum reaction parameters were pH 3.0, 50℃, 2 hours and 20 u/g.