Characterization of rheological properties of rye arabinoxylans in buckwheat model systems

The aim of this investigation was to study the rheological properties (gelation profile, mixing and pastingproperties) of two rye arabinoxylans (AXs) (water-extracted (WEAXs), calcium hydroxide-extracted (CEAXs)) in buckwheat model systems using wholemeal and white flour. To promote gelation in these systems, pyranose 2-oxidase (POx) was added. AX characterization in solution showed a higher gelation profile for the CEAXs (G’: 0.48 Pa, G’’: 0.25 Pa) compared with the WEAXs (G’: 0.21 Pa, G’’: 0.14 Pa), probably due to differences in chemical and structural properties. In buckwheat batter systems, highest rheological properties were achieved when POx was added to the control flours (for wholemeal flour: G’: 40.1 kPa, G’’: 8.6 kPa; for white flour: G’: 18.7 kPa, G’’: 1.4 kPa), whereas most AX concentrations improved these properties to a lower degree. Nearly all wholemeal flour systems reached higher viscoelastic properties when containing CEAXs (G’: 20.0e35.1 kPa; G’’: 4.2e6.7 kPa), while WEAXs improved the majority of these properties in systems made with white flour (G’: 10.4e12.7 kPa; G’’: 2.2-2.3 kPa). No additional effect was seen in the batter viscoelasticity when POx was combined with these AXs. Pasting and mixing properties of the flour systems were mostly reduced by the addition of AXs, while the presence of POx displayed little or no further effect. These observations indicate that AXs could be applied as natural structure-forming agents in GF bread, when used in the right amount.