Effect of Differently Extracted Arabinoxylan on Gluten-Free Sourdough-Bread Properties

Abstract

The role of arabinoxylans (AXs) in bread-making has gained interest due to their positive contribution to bread quality. Therefore, the effect of differently extracted (water, alkaline, or enzymatic) rye AXs on gluten-free (GF) buckwheat and millet batter rheology and bread properties was evaluated. The results showed that the addition of AXs influenced most of the batter and bread properties differently, which depended on the chemical and structural properties of the AXs. All batter systems displayed a typical weak gel behavior. Enzyme- (Pentopan Mono BG-) extracted AXs (PEAXs) were able to strengthen both millet and buckwheat batter structures to a greater degree, as seen by the increase in storage modulus. Regarding bread properties, in buckwheat breads, calcium hydroxide-extracted AX (CEAX) was able to improve the specific volume (from 1.73 to 1.93 cm3/g) and firmness (from 10.88 to 4.69 N) the most, compared to the control. The AXs extracted successively with water and the enzyme Pentopan Mono BG (WPEAX) produced the highest loaf volume (2.39 cm3/g) and one of the lowest crumb firmness values (5.51 N) but caused larger pores and a ruptured crust. In millet breads, water-extracted AXs (WEAXs) and CEAX produced lowest crumb hardness (WEAX: 6.94 N; CEAX: 8.53 N). Specific volume was highest in breads with WEAX (2.35 cm3/g), but CEAX displayed a better pore structure. Overall, water-extracted AXs improved the GF bread properties to a higher extent than alkaline-extracted AXs. Only CEAX displayed a comparable effect in some cases, and considering the fact that alkaline extraction of AX is much more efficient (much higher yield), its application compared to other AXs could be more favorable. Overall, AXs hold great potential as baking improvers for GF bread; the extent of their improvement will be defined by their functional properties.