The Effects of Increasing the Dry-Bulb Temperature during the Stem-Drying Stage on the Quality of Upper Leaves of Flue-Cured Tobacco

Abstract

The control of the curing temperature during the stem-drying stage is important for the quality of upper leaves of flue-cured tobacco. Based on the conventional curing process during the yellowing stage and the leaf0drying stage in the tobacco curing process, in this study, the dry-bulb temperature was increased to 72 and 75 °C in the bulk curing barn during the stem-drying stage to compare with the highest temperature of 68 °C commonly adopted in the bulk curing barn. The result showed that, compared with the conventional temperature setting, the energy consumption cost was reduced by 0.10 or 0.08 USD/kg when the curing temperature was increased to 72 or 75 °C, respectively. Statistical analysis showed that increasing DBT was beneficial to the improvement in the internal quality of flue-cured tobacco leaves. The adjustment of curing temperature also improved the aromatic quality and volume of singe-material tobacco leaves. However, as the temperature continued to increase, the quality improvement in cured upper tobacco leaves showed a decreasing trend. According to the quality of fresh tobacco leaves, an appropriate increase in the dry-bulb temperature based on the conventional temperature setting of 68 °C during the stem-drying stage can improve the usability and economic benefit. The degree of increase in the DBT should depend on the quality of local fresh tobacco growth in the field.