Effect of Milling Methods and Particle Size on Carr’s Flowability and Floodability Indices of Rice Flour

Abstract

Fine grinding technology is expected to permit various application of rice flour, however, it will decrease flowability of rice flour, resulting in formation of bridge and cohesion of powder inside the food processing machine. To determine necessary equipments and technologies for the processing of fine rice flour, this study investigated Carr s flowability and floodability indices, moisture content, and roughness coefficient of the flours made from nonglutinous rice (white/brown) and glutinous rice (white), having the mean diameters of 3-30 m and 30-100 m milled by a jet mill and a hammer mill respectively. Although the moisture content and the roughness coefficient decreased as the mean diameter of the rice flour decreased, its flowability decreased as the mean diameter decreased down to 15 m. In the flours at 3 m mean diameter, the flowability of white rice flour was almost same with that of 15 m flour, while it increased in the brown rice flour. The rice flours with the mean diameter less than 30 m were less flowable than traditional rice flour joshinko, however as flowable as ordinary wheat flour.