Analysis for moisture migration and drying characteristics of flue-cured tobacco veins

ObjectiveMoisture migration and drying characteristics of tobacco leaf veins were explored to provide re-ference for the optimization of flue-curing process. MethodK326 middle leaves were used as test materials. Distribution of tracer dyeing liquor in vascular bundles and moisture migration ratio of tobacco leaf primary veins and branch veins were studied, dehydration and shape changes of tobacco leaves during curing were also analyzed. ResultMoisture of tobacco veins first migrated from primary vein vascular bundle of leaf base, preferentially accessed to the nearest branch veins, and reached the tip part. The moisture migration rate of tobacco primary vein vascular bundles decreased gradually from leaf base to leaf tip. Water migration rate of branch vein vascular bundles increased as it was closer to leaf base. Moisture migra-tion rate of primary vein vascular bundle was higher than that of branch vein vascular bundle. The moisture content in toba-cco leaf decreased during curing from leaf base to leaf tip, and diameter shrinkage rate of tobacco primary vein radually in-creased. The diameter shrinkage rate of primary vein near leaf base was larger before 42 ℃ than that near leaf tip, when the temperature was over 42 ℃, the condition was on the contrary. Diameter shrinkage rate of primary vein between leaf base and leaf tip was the smallest. ConclusionMoisture migration of tobacco vines affects the changes of water content and pri-mary vein shape of tobacco leaves during curing. The relation between migration characteristics and dehydration characteri-stics can provide reference for regulation of tobacco leaf moisture loss and flue-curing process optimization.