Influence of milling methods on physicochemical properties of Thai rice flour (Riceberry) and its application for gluten free crispy waffle

Abstract

The objectives of this research are to study the effect of milling methods (dry milling and semi-dry milling) on components and physicochemical properties of rice flour (Riceberry) and to utilize Riceberry flour in gluten free crispy waffle recipe, replacing wheat flour. Dry-milled riceberry flour contained higher protein content, damaged starch (%) and water absorption index (WAI), compared to semi-dry milling. There was no difference in amylose content of both milled samples. The larger average particle size was found in semi-dry-milled sample, which contained the large particle of fiber and small particle of starch granules as observed by microscope. For pasting properties, pasting temperature, final viscosity, and setback of dry-milled riceberry flour showed the higher values than those of semi-dry-milled sample, while the values of peak viscosity and breakdown of dry-milled flour were lower values than semi-dry-milled flour. In terms of gelatinization and retrogradation, semi-dry-milled riceberry flour consumed larger energy for gelatinization (DH_gel) and showed lower temperatures of gelatinization (To_gel, Tp_gel, and Tc_gel), compared to dry-milled flour. There were small differences in energy (DH_retro) and temperatures (To_retro, Tp_retro, and Tc_retro) of retrogradation of both milled riceberry flour gels after storaged at refrigerated temperature for 7 days. The lower hardness and stickiness values of semi-dry-milled riceberry gel were observed. For utilization, semi-dry-milled riceberry flour may be more suitable ingredient in gluten free crispy waffle, compared to dry-milled rice flour and has potential to replace wheat flour, in term of texture.