Study On Fresh Tobacco Leaves Quality And Key Curing Indicators Of Characteristic Variety CB-1

In order to improve the quality of characteristic tobacco variety CB-1,aiming at the problems of green tendon,gray hanging and stiffness in curing of CB-1,the quality and curing characteristics of CB-1 fresh tobacco,the relationship between the maturity of tobacco leaves,the suitable harvesting methods of upper leaves and the key temperature and humidity indicators of bulk curing and the quality of tobacco leaves were studied.Based on the grade structure and sensory quality of flue-cured tobacco,the effects of different treatments on the quality of tobacco leaves were analyzed by referring to the appearance quality,chemical composition coordination,polyphenols and neutral aroma-producing substances.which provided theoretical and technical support for further showing the fresh-sweetness and honey-sweetness quality characteristics of CB-1.The main results are as follows :(1)Study on quality and curing characteristics of CB-1 fresh leavesThe quality and curing characteristics of fresh tobacco of CB-1 and Yunyan 87 were different.Compared with Yunyan 87,the SPAD value was 2.32 higher,chlorophyll content was 0.10 mg/g FW higher,total moisture,vein moisture and free moisture content were lower,leaf moisture and bound moisture content were higher,total sugar and reducing sugar content were higher;amylase,PPO,SOD,POD activity were higher,the thickness of middle leaves was 3.07 ?m higher,and the thickness of palisade tissue was 8.60 ?m,the structure was denser,and the content of chlorogenic acid was higher..In terms of curing characteristics,CB-1 tobacco leaves natural yellowing speed was slower in black-box.When the tobacco leaves did not completely yellowed,the leaf browning occurred,and the speed of browning was faster,which indicated that CB-1 tobacco leaves had poor curability and curing resistance.(2)Study on the suitable maturity of CB-1There were differences in quality of fresh tobacco at different maturity of CB-1.With the increase of harvesting maturity of fresh tobacco,the content of SPAD,moisture and pigments decreased,the content total nitrogen,nicotine and protein decreased,the thickness of tissue structure of middle leaves decreased,the intercellular porosity increased,the structure of leaves tended to be loose,and the content of chlorogenic acid in middle leaves increased.In terms of curing characteristics,the higher the maturity of tobacco leaves,the faster the natural yellowing speed in black-box,the higher the yellowing degree of tobacco leaves when browning occurs,which indicated that CB-1 tobacco leaves had better curability and curing resistance relatively.The suitable maturity for different parts of CB-1 were different.The suitable maturity of lower leaves was about 60 % yellow-green on the leaf surface,with an average SPAD of 31.04,1/3 of the main veins whitening;the suitable maturity of middle leaves was about 70 % yellow-green on the leaf surface,with an average SPAD value of 29.42 and 1/2 of the main veins whitening;the suitable maturity of upper leaves was about 80 % yellow-green,with an average SPAD value of 27.70 and 2/3 of the main veins whitening.(3)Study on the suitable harvesting methods of the upper leaves of CB-1The study on the harvesting number and mothods of fully mature upper leaves of CB-1 showed that the suitable number of leaves to be harvested at one time was 6,and the suitable harvesting method was 6 leaves with stems.(4)Study on key indicators of bulk curing of CB-1The optimum combination of processing parameters for bulk curing of CB-1 showed that "high temperature,moderate humidity" for lower leaves was best and "moderate temperature and high humidity" for middle and upper leaves was best.The key indicators of bulk curing were: For the lower leaves,in leaf changing stage,the dry-bulb and wet-bulb were 40 ?/ 38 ?,leaves yellowed 50-60 %;in withering stage,the dry bulb and wet bulb were 42 ?/ 37 ?,leaves yellowed 70-80 %;in stem changing stage,the dry bulb and wet bulb were 47 ?/ 38 ?,main veins whitened and shined.For the middle and upper leaves,in the leaf changing stage,the dry bulb and wet bulb were 40 ?/ 39 ?,leaves yellowed 70-80 %;in the withering stage,the dry bulb and wet bulb were 42 ?/ 39 ?,leaves yellowed 90-100 %;in the stem changing stage,the dry bulb and wet bulb were 47 ?/ 39 ?,and main veins whitened and shined.Leaf dring and stem drying of all parts are the same: In leaf drying stage,the dry bulb and wet bulb were 54 ? /39.5 ?,leaves were completely dry;in stem drying stage,the dry-bulb and wet-bulb were 68 ? / 42 ?,and the main veins were completely dry.