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Abstract

A method of treating wood chips or saw dust with an enzyme formulation, prior to refining, in order to reduce the total extractives content of the wood chips or sawdust and to modify the wood structure is described herein. The wood chips or sawdust are treated with one or more enzymes such as lipases, esterases, pectinases, cellulases, laccases, hemicellulases and combinations thereof. The enzyme formulation can be applied to the surface of the wood chips or sawdust, e.g. by spraying, or can be impregnated into the wood chips. The enzyme formulation can further comprise one or more surface active agents which can enhance the effectiveness of the enzyme treatment by improving the diffusion or impregnation of the enzymes into the wood chips. The enzyme-based treatment can be applied at any of several different locations prior to the pulping process including chip piles, chip conveyors, chip silos, chips washers, chip washer water stream, impregnation liquor, or during chip storage. The enzyme-based treatment is quick and easy to apply in most commercial mill operations. The enzyme-based treatment is effective at temperatures from about 20.degree. C. to about 100.degree. C., preferably from about 35.degree. C. to about 70.degree. C. The wood chips or saw dust can be treated for a period of time from about 0.10 to about 200 hours, more preferably from about 10 to about 72 hours. The addition of the enzyme formulation into the wood chip or sawdust pile increases the concentration of pitch-degrading enzymes on the chip or dust surfaces which can significantly accelerate the degradation of pitch components inside the chips or sawdust. Decreasing the total extractives content of the wood chips and modifying the structure of the wood chips or sawdust leads to a decrease in the apparent pitch content during pulping and in reduced energy requirements, increased paper strength, improved paper machine runability, and lower costs associated with paper manufacturing.

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First Claim