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Dornez E.,Catholic University of Leuven | Verjans P.,Catholic University of Leuven | Arnaut F.,Puratos Group NV | Delcour J.A.,Catholic University of Leuven | Courtin C.M.,Catholic University of Leuven
Journal of Agricultural and Food Chemistry | Year: 2011

The bread-improving potential of three psychrophilic xylanases from Pseudoalteromonas haloplanktis TAH3A (XPH), Flavobacterium sp. MSY-2 (rXFH), and unknown bacterial origin (rXyn8) was compared to that of the mesophilic xylanases from Bacillus subtilis (XBS) and Aspergillus aculeatus (XAA). XPH, rXFH, and rXyn8 increased specific bread volumes up to 28%, 18%, and 18%, respectively, while XBS and XAA gave increases of 23% and 12%, respectively. This could be related to their substrate hydrolysis behavior. Xylanases with a high capacity to solubilize water-unextractable arabinoxylan (WU-AX) during mixing, such as XBS and XPH, increased bread volume more than xylanases that mainly solubilized WU-AX during fermentation, such as rXFH, rXyn8, and XAA. Irrespective of their intrinsic bread-improving potential, the dosages needed to increase bread volume to a similar extent were much lower for psychrophilic than for mesophilic xylanases. The xylanase efficiency mainly depended on the enzyme's temperature activity profile and its inhibition sensitivity. © 2011 American Chemical Society. Source

Dornez E.,Catholic University of Leuven | Verjans P.,Catholic University of Leuven | Broekaert W.F.,Fugeia NV | Cappuyns A.M.,Catholic University of Leuven | And 4 more authors.
Cereal Chemistry | Year: 2011

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. ©2011 AACC International, Inc. Source

Damen B.,Catholic University of Leuven | Cloetens L.,University Hospital Gasthuisberg | Broekaert W.F.,Catholic University of Leuven | Broekaert W.F.,Fugeia NV | And 10 more authors.
Journal of Nutrition | Year: 2012

Arabinoxylan oligosaccharides (AXOS) are studied as food compounds with prebiotic potential. Here, the impact of consumption of breads with in situ-produced AXOS on intestinal fermentation and overall gastrointestinal characteristics was evaluated in a completely randomized, double-blind, controlled, cross-over study. Twenty-seven healthy volunteers consumed 180 g of wheat/rye bread with or without in situ-produced AXOS (WR + and WR -, respectively) daily for 3 wk. Consumption of WR + corresponded to an AXOS intake of ~2.14 g/d. Refined wheat flour bread without AXOS (W -) (180 g/ d) was provided during the 3-wk run-in and wash-out periods. At the end of each treatment period, participants collected urine for 48 h as well as a feces sample. Additionally, all participants completed a questionnaire about stool characteristics and gastrointestinal symptoms during the last week of each period. Urinary phenol and p-cresol excretions were significantly lower after WR + intake compared to WR -. Consumption of WR + significantly increased fecal total SCFA concentrations compared to intake of W -. The effect of WR + intake was most pronounced on butyrate, with levels 70% higher than after consumption of W - in the run-in or wash-out period. Consumption of WR + tended to selectively increase the fecal levels of bifidobacteria (P = 0.06) relative to consumption of W -. Stool frequency increased significantly after intake of WR+ compared to WR -. In conclusion, consumption of breads with in situ-produced AXOS may favorably modulate intestinal fermentation and overall gastrointestinal properties in healthy humans. © 2012 American Society for Nutrition. Source

Damen B.,Catholic University of Leuven | Pollet A.,Catholic University of Leuven | Dornez E.,Catholic University of Leuven | Broekaert W.F.,Catholic University of Leuven | And 6 more authors.
Food Chemistry | Year: 2012

Multiple studies have revealed the prebiotic activity of cereal derived arabinoxylan oligosaccharides (AXOS). This study investigated the in situ production of AXOS during bread making. In the first part, the AXOS producing capacity of different xylanases was compared in whole meal bread making. Three mesophilic xylanases originating from Bacillus subtilis, Aspergillus niger and Hypocrea jecorina, and one thermophilic xylanase from H. jecorina (HjXynA), were used in different dosages. At dosages that did not impair dough manageability, HjXynA solubilised and cleaved the arabinoxylan fraction to the largest extent, resulting in an AXOS content of 2.1% (dry basis) and an average degree of polymerisation (avDP) of 9. In the second part, the impact of HjXynA on the AXOS levels in dietary fibre enriched breads was studied. Rye or wheat bran fortified breads treated with HjXynA yielded good quality breads with AXOS levels above 2.0% with an avDP of 26 and 19, respectively. © 2011 Elsevier Ltd. All rights reserved. Source

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