Effects of variety and harvest moisture content on equilibrium moisture contents of rice

Equilibrium moisture contents (EMC) of two long-grain rice varieties (Kaybo nnet and Cypress) and one medium-grain variety (Bengal) were measured at te mperatures of 4, 21, and 38 degrees C with relative humidities (RHs) rangin g from 11 to 96%. In addition to temperature and RH, variety was a signific ant factor affecting rice EMC. Harvest moisture content (HMC) and harvest l ocation did nor significantly affect the EMC of rough rice. Rice harvested at a lower moisture content (MC) had lower EMC values than rice harvested a t a higher MC when equilibrated to high RHs; however these differences were primarily attributed to hysteresis effects. Art EMC model including temper ature, RH, and variety was developed. At most RHs, the EMCs of Bengal, Kayb onnet, and Cypress rough rice were approximately 0.2 to 0.8 percentage poin ts higher than that calculated from the Chung EMC equation. New coefficient s of the Chung equation for rough and milled rice are provided.