COMPARISON OF 5 3-PARAMETER EQUATIONS FOR THE DESCRIPTION OF MOISTURESORPTION DATA OF MUSTARD SEEDS

Equilibrium moisture contents (EMC) of seeds of yellow, brown, and ori ental mustards were determined at five different temperatures (2, 10, 25, 40, and 55-degrees-C) by equilibrating about 10-g samples at relat ive humidities in the range of 11-96%, obtained using saturated salt s olutions. The EMCs of all three types of mustard decreased with an inc rease in temperature at constant relative humidity. At most temperatur es and at the relative humidities tested, oriental mustard seeds had t he lowest, yellow mustard the highest, and brown mustard intermediate EMC values. Differences in the moisture adsorption characteristics of the three mustards were attributed to differences in mucilaginous mate rial, oil and protein contents of the seed. The modified GAB equation together with four other commonly used three-parameter equations (modi fied Henderson, Chung-Pfost, Halsey, and Oswin equations) were evaluat ed for their ability to fit the experimental data for the three types of mustard. The modified GAB equation gave the best fit to the experim ental data and the modified Oswin equation was the second best model f or describing the EMC data of mustard seeds. The predicted safe storag e moisture contents of oriental, brown and yellow mustard seeds at 25- degrees-C were 10.0, 10.6 and 10.7% (db), respectively.