Abstract
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.
Highlights
GF bread formulations have been continuously developed to overcome most of the problems that arise due to the absence of gluten, such as low bread volume, friable crumb, and poor mouthfeel
Since the rheological behavior of GF batter is majorly influenced by the starch properties and water content [6,7,8], this study aimed to investigate the role of GF starch from different sources, as well as the rheological behavior of GF batter and the final bread quality after baking with ohmic heating
Color of the bread crumb remained unaffected by the different heating methods, while the crust color of conventional bread was darker due to an intense Maillard reaction that did not occur in ohmic-heated bread. These findings demonstrated that GF bread quality was significantly influenced by the starch:water ratio and batter viscosity, and to a large extent by the starch/flour properties
Summary
GF bread formulations have been continuously developed to overcome most of the problems that arise due to the absence of gluten, such as low bread volume, friable crumb, and poor mouthfeel. The most recent approach to improve GF bread quality is applying a non-conventional baking technology: ohmic heating. Ohmic heating is a volumetric heating method that passes an electrical current through food, resulting in fast and uniform heating [1]. This technology has been successfully applied for baking GF bread, improving bread volume and pore properties [2]. It is known that the structure and, quality of GF bread is mainly controlled by starch, which has a significant effect on the batter viscosity and stability [3,4]. Since starch is the main component in a GF formulation, the GF batter commonly requires more water compared to wheat bread. Schoenlechner et al [5] highlighted that water content in GF bread controlled the starch gelatinization, which significantly affected gas retention
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