Effect of a Xylanase from the Thermophilic Thermomyces lanuginosus on Wheat Flour Breadmaking Quality

摘要

A xylanase from the thermophilic fungus Thermomyces lanuginosus CBS288.54 was purified and evaluated for its suitability in wheat flour breadmaking. Xylanase was purified 33.6-fold to homogeneity with a recovery yield of 21.5% It appeared as a single protein band on SDS-PAGE gel with a molecular mass of approx. 26.2 kDa. The purified xylanase was most active in the neutral pH, namely pH 7.0-7.5, and exhibited its optimal activity at 70-75°C The study was further carried out to investigate the effect of the purified xylanase on the properties of wheat bread and its staling during storage. The presence of xylanase in the dough improved the bread-making quality (i.e. specific volume and crumb structure) and provided an anti-staling effect on breads. Addition of purified xylanase at 1.5 ppm (mg/kg flour basis) was found to be the most suitable, and caused approx 43.2% increase in bread specific volume in comparison with the control. The crumb-firming kinetics was fitted the Avrami equation. It was shown that the thermostable xylanase retarded the bread staling process by reducing the initial crumb firmness and slowing down the firming process during storage. Hence, the xylanase seems to be useful to improve the quality of bread.