The carbohydrase preparation supplement was a preparation of Thermo stable endo-1,4-β-xylanase produced by Trichoderma reesei with a xylanase activity of 160,000 BXU/g, where a unit is defined a 1 µmol of reducing sugar released per minute on a birch wood xylan substrate (0.5%) at pH 5.3 under the condition of the assay (AB Enzymes, Darmstadt, Germany)