Whipping Behavior of Rice Flour Dough

Abstract

In this study, the bubbles in rice flour dough were investigated under a constant temperature. The bubble size distribution is important for the control of food texture. If bubble sizes depend mainly on the inertial force, viscous force, and surface tension, then the normalized mean bubble diameter should be a function of the Reynolds number and Weber number. We obtained experimental data using a hand mixer, and compared the properties of doughs prepared using six rice flours; each flour was prepared through a different milling process. We also added the size effect of the rice flour particles as the Bond number. Furthermore, we performed a dynamic wettability test to estimate the wettability of the rice flour surface. The results of this test were described well by the Washburn equation, and dccosθ was calculated as a wettability parameter (where, dc: effective diameter of a capillary in a powder bed, cosθ: the contact angle). The mean bubble diameter (dbm) generated by whipping was expected to be affected by the thickness (d) of the rod of the mixer, its movement speed, physical properties of the material, and gravitational acceleration. Therefore, dimensionless mean diameter (dbm/d) was expressed by a dimensionless equation. The empirical equation obtained was generally applicable to the variety of materials selected for this study.