Moisture migration characteristics and the influencing factors in cherry red tobacco leaves
To investigate the moisture migration characteristics in cherry red tobacco leaves and the influencing mechanisms of key factors,cherry red leaves and conventional leaves sampled from the same tobacco plant were compared using a moisture sorption analyzer and low-field nuclear magnetic resonance(LF-NMR)technology.The moisture adsorption-desorption properties of the cherry red leaves were evaluated and the moisture occurrence pattern in the cherry red leaves was microcosmically characterized.The surface morphology,microstructure,chemical composition,and glandular trichome secretion composition from the tobacco leaves were analyzed to obtain the action-response relationship of the factors affecting the differences in moisture absorption characteristics between the cherry red leaves and conventional leaves.The results showed that the total content of hydrophilic sugars in the cherry red leaves was 11.10%-16.04%lower than that of the conventional leaves,while the total contents of hydrophobic higher fatty acids and higher aliphatic alkanes were 11.15%-16.08%and 6.06%-6.40%higher than those of the conventional leaves,respectively.In addition,the cherry red leaves had smaller average pore sizes(27.38-159.86 nm)and lower porosity(4.20%-5.65%)compared to those of the conventional leaves.Consequently,the moisture migration rate and moisture migration kinetic parameter(effective diffusion coefficient,Deff)were lower in the cherry red leaves.Under higher humidity conditions(>40%RH),the equilibrium dry basis moisture content of the cherry red leaves was also lower than that of the conventional leaves.In the moisture adsorption-desorption cycle test,the cherry red leaves showed superior moisture retention with a hygroscopic hysteresis ΔMCe of 1.22%at 40%RH compared to 0.14%for the conventional leaves.It is known that tobacco leaves contain three forms of moisture:free moisture,irreducible moisture,and bound moisture.In particular,the cherry red leaves had an increased moisture binding capacity and resistance to desorption compared to the conventional leaves.The identified key factors affecting the moisture migration behavior of the cherry red leaves during processing provide fundamental data and evaluation techniques for the control and regulation of their processing technology.
Cherry red tobacco leafMoisture migrationDynamic moisture absorption-desorptionLow-field nuclear magnetic resonanceMoisture occurrence pattern
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