Isothermal drying kinetics of differently processed reconstituted tobacco for heated tobacco products

In order to study the moisture migration kinetics during the drying process of reconstituted tobacco for heated tobacco products and to investigate the influences of different processing technologies and glycerin contents on the drying characteristics of the reconstituted tobacco materials, isothermal drying experiments on the reconstituted tobacco samples prepared by the rolling process, paper-making process, dry process and slurry process with different glycerin contents were conducted at 50-90 ℃. An isothermal model describing the drying kinetics for the reconstituted tobacco was established based on the data obtained by thermogravimetric analysis. The results showed that: 1) There were four stages in the drying process of the reconstituted tobacco: accelerated drying, drying at a constant rate, first and second decelerated drying. 2) Based on the characteristics of the drying process, a segmented isothermal drying kinetics model was established. The fitting effect R² was greater than 0.995 2 and the RMSE was less than 0.002 8. The established model could describe the law of moisture migration in the isothermal drying process accurately. 3) The increase of glycerin content increased the equilibrium moisture content in the reconstituted tobacco during drying. With the increase of glycerol content, the drying rate constant K₁ increased, while K₂ and K₃ decreased. 4) Under the same drying condition, the drying rate for the four processing technologies were in the order of paper-making process > drying process > rolling process > slurry process.