Ohmic baking of gluten-free bread: Role of starch and flour on batter properties

The viscosity of gluten-free (GF) batter significantly influences GF bread quality. This study attempts to understand how the rheological properties of GF batter are affected by the type of starch and the amount of water and how they influence GF bread properties when baked with two methods (conventional oven, ohmic heating). For this purpose, the physical and chemical properties of different starches (corn, wheat, potato, cassava) and GF flours (rice, buckwheat) were evaluated. Rheological behavior of GF batter was not only influenced by the starch:water ratio, but also greatly by the starch source and structure, which influenced its physical properties (e.g., water holding capacity, swelling power, solubility, starch damage, and pasting properties). All batters consistently exhibited shear-thinning and dominant viscous behavior. Between viscosity and ohmic-heated bread properties, a non-linear relationship was observed. Two categories of required water content or viscosity ranges were defined for estimating final GF bread properties: low water content with a viscosity range of 47.12–56.20 Pa·s for B-type starches, and medium water content with a low to medium viscosity range of 2.29–15.86 Pa·s for A-type starches. This finding could be useful for further research to design GF batter viscosities for tailored bread quality.