Desorption and Sorption Isotherms of Different Varieties of Hemp Seeds with Different Percentages of Dockage under Different Temperatures and Different Relative Humidities

Hemp cultivation faces challenges due to the adoption of dioecious cultivars, which suffer from biomass loss and fibre heterogeneity. In contrast, monoecious cultivars offer simultaneous fibre and seed production, albeit with lower fibre quality. Understanding the drying characteristics and storage requirements of hemp seeds is crucial for effective post-harvest management. This study explored the moisture sorption and desorption isotherms of two common Canadian hemp seed varieties, Altair (dioecious) and CanMa (monoecious), by using both saturated salt solution (SSS) and thin-layer drying methods. Their isotherms were also compared with the published isotherm of Finola—a common dioecious variety in Europe. The thin-layer drying method yielded higher EMC values than the SSS method due to incomplete equilibrium attainment. Larger EMC differences existed between different seed types (dioecious vs. monoecious), and this difference was small between the same seed types (dioecious vs. dioecious). The GAB equation provided the most accurate prediction of equilibrium moisture contents for both varieties.