Analysis on variation of moisture state and shape of flue-cured tobacco upper leaves with stalk during curing

Objective In the present study,dehydration drying characteristics of flue-cured tobacco leaves with stalk during curing were investigated to provide a theoretical basis for optimization of curing technology.Method The variation of moisture content,state and shape shrinkage in tobacco leaves with stalks were determined during curing,and compared with those of tobacco leaves without stalks.In addition,the correlation between water index and shape index of tobacco leaves was analyzed.Result Moisture content in leaf,blade and midrib of tobacco with stalk was higher than that of tobacco without stalk,the moisture transport characteristics of tobacco leaf with stalk during curing were as follows:free water in tobacco stalk transported to tobacco blade and tobacco midrib,which made free water content and proportion in blade and midrib of tobacco with stalk higher than those of tobacco leaves without stalk.Thickness shrinkage rate of tobacco blade with stalk was significantly smaller than that of tobacco blade without stalk before leaf drying (P<0.05,the same below).However,thickness shrinkage rate of tobacco blade with stalk was significantly higher than that of tobacco blade without stalk after leaf drying.Diameter shrinkage rate of tobacco midrib with stalk was significantly smaller than tobacco midrib without stalk during curing.There was extremely significant positive correlation between free water content in tobacco blade and its moisture content rate,and between free water in tobacco midrib and its moisture content rate.Conclusion Tobacco shape shrinkage is closely related to free water content and moisture content rate.Tobacco moisture content and state can be judged through tobacco shrinkage.