The selection of sorption isotherm equations for wheat based on the fitting of available data

Abstract

Thirty-three sources of EMC/ERH data for wheat were identified, from which 1109 experimental points were extracted. Nineteen sources covered a range of temperatures. Five commonly cited EMC/ERH equations, Chen-Clayton, Modified-Chung-Pfost, Modified-Henderson, Modified-Oswin and Strohman-Yoerger, were compared for their ability to fit 29 sets of wheat data from these 19 sources. The Modified-Chung-Pfost and the Modified-Oswin equations gave the best fit for r.h. = f( M, T) and M = f(r.h., T) respectively. Both equations were then used to fit sub-sets of the data comparing adsorption, desorption, low temperature, hard, soft and durum varieties with the overall fit to the data. The adsorption and desorption equations gave quite distinct curves. The low temperature fit did not differ greatly from the overall. Amongst the varieties, the hard wheat at low temperature showed the greatest difference from the overall fit. The larger data set than previously available and the equations fitted provide a sound basis for future work on the drying and storage of wheat.