Arcila Jennifer A, Weier Steven A, Rose Devin J
Department of Food Science & Technology, University of Nebraska-Lincoln, Lincoln, NE, USA.
The Food Processing Center, University of Nebraska-Lincoln, Lincoln, NE, USA.
Food Res Int. 2015 Aug;74:217-223. doi: 10.1016/j.foodres.2015.05.005. Epub 2015 May 8.
The dietary fiber in wheat bran, principally non-starch polysaccharides (NSP), is mostly water-unextractable and is poorly utilized by human gut microbiota. The purpose of this study was to determine the change in water-extractability of NSP in wheat bran upon extrusion and then to determine if extrusion impacts the availability of NSP for fermentation by the fecal microbiota during in vitro fecal fermentation. A secondary objective was to incorporate extruded bran into a product formulation to determine if changes in WE-NSP and NSP fermentation were maintained in a finished product. Bran was extruded using combinations of high or low moisture (15% and 30% wb) and high or low screw speed (120 and 250rpm). All extrusion conditions resulted in increases in WE-NSP and fecal microbiota short chain fatty acid (SCFA) production upon fermentation compared with unextruded bran. Low screw speed and low moisture resulted in the greatest increase in WE-NSP (3-fold) as well as the highest production of SCFA during fermentation (1.4-fold) compared with unextruded bran. Whole wheat breads containing extruded bran did not show increases in either WE-NSP or SCFA production compared with the control. In conclusion, extrusion of wheat bran increased WE-NSP, which enabled greater fermentability by human fecal microbiota. However, once extruded bran was used in a whole wheat bread formulation the changes in fermentation outcomes were no longer evident.
麦麸中的膳食纤维主要是非淀粉多糖（NSP），大多不溶于水，且难以被人体肠道微生物群利用。本研究的目的是确定挤压处理后麦麸中NSP的水可提取性变化，进而确定挤压处理是否会影响体外粪便发酵过程中NSP被粪便微生物群发酵的可利用性。第二个目标是将挤压后的麦麸纳入产品配方，以确定在成品中水溶性非淀粉多糖（WE-NSP）的变化和NSP发酵情况是否得以保持。使用高或低水分含量（15%和30%湿基）以及高或低螺杆转速（120和250转/分钟）的组合对麦麸进行挤压。与未挤压的麦麸相比，所有挤压条件均导致发酵后WE-NSP增加以及粪便微生物群短链脂肪酸（SCFA）产量增加。与未挤压的麦麸相比时，低螺杆转速和低水分含量导致WE-NSP增加最多（3倍），同时发酵过程中SCFA产量最高（1.4倍）。与对照组相比，含有挤压麦麸的全麦面包在WE-NSP或SCFA产量方面均未增加。总之，麦麸挤压增加了WE-NSP，这使得其更易被人类粪便微生物群发酵。然而，一旦将挤压后的麦麸用于全麦面包配方，发酵结果的变化就不再明显。
