上部烟叶带茎烘烤中主要化学成分变化

研究了烘烤过程中上部叶采收带茎与不带茎烟叶主要化学成分变化规律。结果表明,(1)烘烤期间带茎烟叶的总水分表现为前期下降缓慢后期下降较快,束缚水则缓慢地散失,自由水的失水高峰早于总水分,在24～48h内,自由水含量有所增加,带茎烟叶的失水速度明显低于不带茎烟叶,表明此段时间带茎烘烤下茎杆中的自由水分向叶片内发生了运移。(2)烘烤期间带茎烟叶淀粉含量低于不带茎烟叶,烤后则稍有下降;可溶性总糖和还原糖的含量在72h前增加幅度较大,之后有所降低,烤后两者都低于不带茎烟叶。(3)烘烤期间带茎烟叶总氮变化不大,硝酸盐和亚硝酸含量表现为前期上升后期下降的规律,烤后硝酸盐含量稍有降低,亚硝酸盐含量则稍有升高,钾含量也稍有增加。

Major Chemical Component Changes in Upper Tobacco Leaves with Stalk during Flue-curing

The changes of major chemical components of DJ(Treatment 1,upper leaves harvested and cured with stalk) and WJ(Treatment 2,upper leaves harvested and cured without stalk) during flue-curing were studied.The results showed that:(1) the loss rate of total water in tobacco leaves with stalk was slow in the first 48 hours and then increased sharply,while the bound water decreased gradually with the proceeding of curing.The peak of free water loss came earlier than the total water.The free water increased a little from 24 to 48 hours.The ratio of total water loss in DJ was evidently lower than that in WJ between 24h and 72h,which showed that the transport of free water from stalk to leaf.(2) The content of starch in DJ was lower than that in WJ during the process,and decreased in cured leaves.The total sugar and reducing sugar in DJ increased quickly during the first 72 hours,and then decreased,whereas lower than those in WJ.(3) Little change occurred in the total nitrogen of DJ during the process,and the contents of nitrate and nitrite increased quickly in the first 72 hours followed by rapid decrease afterwards.The content of nitrate exhibited a slight decline,whereas the nitrite and potassium increased slightly.