Sorptional Parameters of Sunflower Seeds of Use in Drying and Storage Stability Studies

The Othmer method was applied to the experimental isotherms to obtain the heat of sorption, in turn compared with predictions by a model based on the modified Halsey isotherm and the Clapeyron equation. Agreement was good, since the ratio of heat of sorption to heat of vaporisation of pure water Lb/Lw was predicted with a standard error of 0·016. Latent heats calculated for assumed drying conditions at the surface grain moisture were between 18 and 59%, as high as those evaluated at the average grain moisture. As most bulk drying models assume surface evaporation, use of the higher latent heat may reduce their typical tendency to overestimate grain heating.