A mean moisture content-equilibrium relative humidity relationship for nine varieties of wheat

A mean moisture content-equilibrium relative humidity relationship for nine varieties of wheat at 25°C is presented, for which the curves were fitted by eye. The mean safe storage moisture content in equilibrium with 70% relative humidity (r.h.) for all the wheat varieties adsorbing moisture was 14.7% (wet weight basis) but if varietal differences and errors in measurement are taken into account, the moisture content of stored wheat may need to be as low as 13% to be safe from attack by mites. The hysteresis between adsorption and desorption reached a maximum of 0.7% moisture content at 40–50% r.h. Hysteresis was found to be statistically significant up to 75% r.h. Equilibrium moisture contents were calculated from data transformed using the Chung and Pfost equation and compared with the measured moisture contents.