Sorption isotherms of tobacco (Nicotiana tabacum L.) seeds

The moisture sorption capacity of tobacco seeds is decisive for their safe long-term storage; therefore, the analysis of the sorption isotherms, in a wide temperature and water activity range, is essential for seed quality maintenance in storage. In this study, the equilibrium sorption isotherms of tobacco (N. tabacum L.) seeds, “Kroumovgrad 90” variety of Oriental tobacco, were determined. The experimental data were obtained by the static gravimetric method at different temperatures and water activities. Sorption isotherms showed a typical Type II sigmoidal profile, with a significant hysteresis effect and a decrease of seed sorption capacity with the increase of temperature. The best fitting with tobacco seed sorption isotherms were the modified Chung-Pfost (desorption) and Oswin (adsorption) models. The monolayer moisture content, important for the safe storage of tobacco seeds, was also determined. The outcomes from the study might be of practical use in tobacco seed conditioning and storage design.