Flash Drying and Milling Techniques for High Moisture Brown Rice

Abstract

ABSTRACT FOR several years there has been an interest among researchers to flash-dry the hull and shell high-moisture rough rice, to flash-dry the bran and to mill high-moisture brown rice and then to dry high-moisture milled rice. This paper describes experiments that utilized heated air to flash-dry bran layers on high-moisture brown rice while the grains were being milled. Temperature of the drying air was 55°C. A 40-s milling period was used along with 810, 1,020, 1,310 and 1,500 rpm abrasive mill speeds with brown rice of 16, 18 and 20% moisture content. Recovery rates (wt. of milled rice to brown rice) between 86 and 98% were observed. With a recovery rate of 91%, the broken ratio (wt. of broken grains to total milled rice) was 0.1% or less. Energy consumption to mill the high-moisture brown rice was significantly reduced when compared to control experiments in which brown rice was milled at storage moisture. However, the control samples showed more whiteness and had a higher bulk density than the high-moisture milled rice.