ADSORPTION EQUILIBRIUM MOISTURE CONTENTS OF LONG-GRAIN ROUGH RICE

ABSTRACT The effects of temperature, relative humidity, and initial moisture content on equilibrium moisture content of long-grain rough rice under adsorptive conditions were investigated. Air temperatures of 12.5, 15, 20, and 30 C, relative humidities of 70, 80, and 90%, and initial moisture contents ranging from approximately 9% to 15% w.b. were used to obtain equilibrium moisture content data. For a given air condition, equilibrium moisture content varied linearly with initial moisture content. A difference of one percentage point in equilibrium moisture content was measured when rice samples at initial moisture contents of 9% and 15.5% were equilibrated to an air condition of 30 C and 90% relative humidity. Equations were developed to relate equilibrium moisture content to initial moisture content, temperature and relative humidity. The Modified Henderson and Chung equations were modified to include the contribution of initial moisture content in predicting equilibrium moisture content.