SELECTION OF EMC/ERH ISOTHERM EQUATIONS FOR SHELLED CORN BASED ON FITTING TO AVAILABLE DATA

Abstract

Five hundred and ninety-one experimental EMC/ERH data points for shelled corn are extracted from twenty publications identified in literature. These data are grouped into adsorption, desorption, average, yellow dent, dent and yellow flint data sets according to varieties and sorption processes, Thirteen out of the twenty publications contain data over a wide range of temperatures, thus producing nineteen data sub-sets suitable for comparing EMC/ERH isotherm equations. Three commonly cited shelled com EMC/ERH equations (Modified-Henderson, Modified-Chung-Pfost and Modified-Oswin equations) are evaluated for their ability to fit these nineteen data sub-sets. The evaluation, based on the residual sum of squares (RSS), standard error of estimate (SEE) and mean relative deviation (MRD), shows that the Modified-Oswin and Modified-Chung-Pfost equations have a better ability to describe the EMC/ERH isotherms of shelled com, with the Modified-Oswin equation slightly better than the Modified-Chung-Pfost equation. Both equations are then used to fit the adsorption, desorption, average, yellow dent, dent and yellow flint data sets and the best fitted coefficients are given. These fitted equations are based on a large data set and therefore provide a sound basis for future work on drying and storage of shelled com.

Key Words and Phrases:

• adsorption
• desorption
• drying
• equilibrium moisture content
• equilibrium relative humidity
• Modified-Chung-Pfost equation
• Modified-Oswin equation
• maize