Influence of thermostable lipase treatment of thermomechanical pulp (TMP) on extractives and paper properties

During mechanical pulping processes, extractives are released from the fibres and accumulate in the process waters, thus affecting both the papermaking process and the product quality. Triglycerides are key compounds responsible for these problems. Lipases can effectively hydrolyse triglycerides to fatty acids, but the high temperatures in the pulping processes can limit their enzymatic activity. Therefore, thermostable lipases have recently been developed. In this work, the effects of enzymatic treatment with Resinase HT at high temperatures on triglyceride concentrations and on paper properties were evaluated. Lipase treatment even at 800 degrees C decreased the amount of triglycerides in the pulp up to 70%. The increase in temperature decreased the enzymatic activity, thus decreasing the triglyceride hydrolysis and increasing the required enzyme dosages. Within the limits of the experimental error, Resinase HT treatment did not affect the optical properties of the sheet, while the mechanical properties appeared to be slightly improved.