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In Situ Production of Prebiotic AXOS by Hyperthermophilic Xylanase B from Thermotoga maritima in High-Quality Bread

¹Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001, Leuven, Belgium. ²Fugeia NV, Wetenschapspark Arenberg, Bioincubator Leuven, Gaston Geenslaan 1, B-3001, Leuven, Belgium. ³Division of Chemical and Biochemical Process Technology and Control, Department of Chemical Engineering, Katholieke Universiteit Leuven, W. de Croylaan 46, B-3001, Leuven, Belgium. ⁴Puratos Group NV, Industrielaan 25, Zone Maalbeek, 1702 Groot-Bijgaarden, Belgium. ⁵Corresponding author. Phone: (+32) 16 321917. Fax: (+32) 16 321997. E-mail: christophe.courtin@biw.kuleuven.be

In situ enrichment of bread with arabinoxylan-oligosaccharides (AXOS) through enzymic degradation of wheat flour arabinoxylan (AX) by the hyperthermophilic xylanase B from Thermotoga maritima (rXTMB) was studied. The xylanolytic activity of rXTMB during breadmaking was essentially restricted to the baking phase. This prevented problems with dough processability and bread quality that generally are associated with thorough hydrolysis of the flour AX during dough mixing and fermentation. rXTMB action did not affect loaf volume. Bread with a dry matter AXOS content of 1.5% was obtained. Further increase in bread AXOS levels was achieved by combining rXTMB with xylanases from Pseudoalteromonas haloplanktis or Bacillus subtilis. Remarkably, such a combination synergistically increased the specific bread loaf volume. Assuming an average daily consumption of 180 g of fresh bread, the bread AXOS levels suffice to provide a substantial part of the AXOS intake leading to desired physiological effects in humans.