Tobacco leaf moisture drying model during flue curing based on leaf water holding capacity

ObjectiveThe relationship between moisture drying model parameters and water holding capacity of to-bacco leaves from different tobacco production areas,tobacco varieties,and stalk positions were studied in this experi-ment in order to provide a simple and easy method for moisture prediction during flue curing process and lay a foundation for precise flue curing.MethodLeaves at different stalk positions of flue-cured tobacco varieties K326 and Yunyan87 in Jiangxi and Hunan were used as test samples. Weighing method was used to measure the water holding capacity of different leaves,moisture content variation in tobacco leaves during curing was fitted combining moisture drying model principle and moisture drying model. Regression analysis was used to analyze water holding capacity of tobacco leaves and the model parameters.ResultWater holding capacity of leaves at different stalk positions increased with the rising of stalk poso-tions. Among different flue-cured tobacco varieties,water holding capacity of K326 was always higher than Yunyan 87. Water holding capacities of tobacco leaves from Jiangxi tobacco production area were always higher than those from Hunan tobacco production area,except that water holding capacity of K326 upper leaves in Hunan tobacco production ar-ea were higher than those from Jiangxi. Fitting determination coefficient R2 of Wang and Singh model were all bigger than 0.95 in different tobacco production areas,tobacco varieties and stalk positions. In the model,drying parameter a was positively correlated to water holding capacity of tobacco leaves,but it was negatively correlated with drying parameter b. The linear regression result between water holding capacity and model drying parameter a and b indicated that the signifi-cant level P of water holding capacity and model drying parameter a and b were smaller than 0.05,and linear fitting deter-mination coefficient(R2)were higher than 0.95.ConclusionThe change of tobacco leaf moisture ratio is in line with the Wang and Singh model during normal bulk curing process,and there is extreme significant correlation between water holding capacity of tobacco leaves and drying model parameter a and b. Therefore,changes of tobacco leaves moisture during flue curing process can be predicted by accurate prediction model for water holding capacity of tobacco leaves.