Improvement of gluten-free bread by addition of pentosans from rye bran

The polysachcharide arabinoxylan, a pentosans is the most important thickening component in rye for bread making in combination with sourdough fermentation. It is important to distinguish between water-extractable/soluble AX, which is responsible for positive effects on water holding capacity, bread volume, crumb texture as well as retrogradation characteristics and water-unextractable/unsoluble AX, which causes the contrary. Although different hydrocolloids and other agents are well investigated for gluten-free breads, the use of pentosans has not been exploited in this respect. The aim of the study was therefore to improve the performance of gluten-free bread baking by addition of different amounts of pentosans. Pentosans used were isolated from rye bran and were analysed for its chemical composition, monosaccharide distribution and protein content. The remaining gluten content was calculated based on RP-HPLC analysis and was aimed to be below 20 ppm. Baking experiments with various gluten-free raw materials (gluten-free wheat starch, amaranth, quinoa, millet and others) and different amounts of pentosans were performed. Rheological properties were characterized by a Micro-Z-Arm-Mixer similar to Farinograph measurements. The addition of pentosan isolates showed significant better technological properties of gluten-free dough systems, especially dough stability and extensibility were improved. Gluten-free bread volume was higher, crumb firmness softer when compared to the control bread (no pentosan addition). The results suggest that pentosan has a good potential to improve gluten-free bread quality