Equilibrium Moisture Characteristics of Raw and Parboiled Paddy, Brown Rice, and Bran

Abstract

Abstract Equilibrium moisture content (EMC) of raw and parboiled paddy, brown rice, and bran were obtained by equilibrating them at 20–80% equilibrium relative humidity (ERH) at 13, 30, and 40°C above saturated inorganic salt solutions. Four EMC-ERH models namely modified Henderson, modified Chung-Pfost, modified Halsey, and GAB were fitted to the observed data and were evaluated using mean relative percent error, standard error of estimate and residual plots. At a constant relative humidity, equilibrium moisture content decreased with increasing temperature. The GAB model described the EMC data the best, modified Henderson and modified Chung-Pfost equations gave good fit while the modified Halsey model gave a poor fit. The heat of vaporization (h fg) of raw and parboiled paddy at different grain moisture contents and temperatures was estimated from EMC data and using the Clausius–Clapeyron equation.