Thermoresistant xylanases from Trichoderma stromaticum: Application in bread making and manufacturing xylo-oligosaccharides

The enzymes Xyl1 and Xyl2 from T. stromaticum were purified and identified by mass spectrometry (MALDI-TOF/MS). Xyl1 contained three proteins with similarity to xylanase family 10, 62 and anarabino-furanosidase of the Trichoderma genus and Xyl2 contained a protein with similarity to endo-1,4-beta-xylanase. High xylanase activity was found at 50 degrees C for Xyl1 and 60 degrees C for Xyl2 and pH 5.0 for both, retaining more than 80% of activities for one hour at 60 degrees C and pH 5-8. Ag2+ and beta-mercaptoethanol increased while SDS and EDTA inhibited the xylanase activity of both Xyl1 and Xyl2 extracts. The Km and V-max values for purified Xyl2 were 9.6 mg/mL and 28.57 lmol/min/mg, respectively. In application tests, both Xyl1 and Xyl2 were effective in degrading beechwood xylan to produce xylo-oligosaccharides. In baking, adding Xyl1 increased the softness and volume of wheat bread and whole grain bread, qualities increasingly desired by consumers in this segment. (C) 2016 Elsevier Ltd. All rights reserved.