Near equilibrium moisture content values for hull-less oats

Sorption characteristics of hull-less oats were obtained by thin layer drying (TLD) and equilibrium relative humidity (ERH) methods. For the TLD method, oats were at initial moisture contents of 11, 16, and 22% [dry basis (db)] and the air was conditioned to obtain relative humidities of 27, 37, 48, 61, 68, 69, 75, 88, and 93% at temperatures from 15 to 35 degreesC. For the ERH method, low (7.6 to 8.7% db) and high (19.6 to 21.2% db) initial moisture content samples were used at temperatures from 15 to 35 degreesC. A significant difference exists between the values of equilibrium moisture content (EMC called 'apparent hysteresis') obtained by two methods. Apparent hysteresis was 0.68 to 1.06 and 0.46 to 3.62 percentage points for the TLD and ERH methods, respectively. High apparent hysteresis in the ERH method is attributed to the fact that it failed to attain EMC in 20-24 h as is suggested in the literature. Additional tests for extended time for ERH method narrowed the apparent hysteresis, indicating that trite EMC values were not obtained by the ERH method.