Moisture Absorption Characteristics and Causes of Tobacco Stem with Different Sizes and Structures

Purpose To study the moisture absorption characteristics of slim stem, medium stem, and stalk epidemis flap, so as to optimize the grouping processing technology of tobacco stem with different sizes and structures.

Methods The moisture absorption characteristics of three types of stem were tested with a self-made device for analyzing heat and moisture characteristics of tobacco stem, the microstructure of the epidermis and cross-section of the stems were observed with a scanning electron microscope, and the chemical composition of tobacco stem was detected by continuous flow analyzer.

Results The moisture absorption capacity of slim stem, medium stem and stalk epidemis flap decreased in turn. With the increase of air humidity, the moisture absorption rate and the equilibrium moisture content increased. The moisture absorption curve could be effectively fitted by Weibull model. The number of pore in the epidermis of slim stem, medium stem and stalk epidemis flap decreased in turn; the pore size of cross-section medium stems and slim stems was obviouslylarger than that of stalk epidemis flap. The contents of total sugar, reducing sugar and total alkaloids in slim stem, medium stem and stalk epidemis flap decreased in turn, while the content of proteinincreased in turn.

Conclusion The moisture absorption rates of slim stem, medium stem, and stalk epidemis flap are positively related to their pore development, and their moisture absorption ratesincrease with the increase of air humidity. The equilibrium moisture content of stalk epidemis flap,medium stem, and slim stem increases in turn, because the total sugar or reducing sugar contentincreases in turn, providing more water absorption sites. Therefore, the moisture absorption characteristics of tobacco stems with different sizes and structures are obviously different. It is necessary to group the tobacco stems according to their sizes and structures.