Study On The Causes Of The Discoloration Of Tobacco Leaves After Baking And The Preventive Measures

In recent years,the discoloration of roasted tobacco leaves has become a prominent issue in the production of tobacco leaves in China,which has seriously reduced the appearance quality and grade structure of the roasted tobacco leaves.In order to clarify the causes of the fading problem of tobacco leaves and the influencing factors,the research and development of control measures to prevent the fading of tobacco leaves after baking were carried out.Finally,a technical specification for preventing the fading of tobacco leaves after roasting was put into practice.In this paper,Yunyan 87 was used as experimental material,and three trials were conducted in 2016 and 2017.The effects of three kinds of light intensity on the pigment and color values of the two types of soil after baking were set,and the degree of fading of the tobacco leaf was set.Flue-cured tobacco cultivated from four soil types was analyzed under indoor conditions for changes in flue-cured tobacco pigments,color values,and conventional chemical components,and comprehensive production techniques were set to optimize the effects of fading on the fading of three flue-cured tobacco production points.The changes of pigment,color value and chemical composition of tobacco leaves during the process of flue-cured tobacco discoloration were analyzed,and the influencing factors of soil and tobacco contents on the fading of tobacco flue were clarified.The scientific storage of cured tobacco leaves,the discrimination of flue-cured tobacco and the prevention of tobacco leaf were established.Fading production measures provide a theoretical basis and scientific basis.The main findings of this article are as follows:(1)Under different light conditions,the contents of various pigments,color difference and chroma of flue-cured tobacco decreased.With the increase of light intensity,the indexes of flue-cured tobacco decreased more obviously.Under the same light intensity,the decline of flue-cured tobacco in sandy muddy field was larger than that of purple soil,and the carotenoid decreased 0.911 mg·g-1,the color b value dropped by 13.9,the chromaticity Y decreased by 15.1.The results of clustering analysis established MLP neural network model,the fading degree of tobacco leaves were divided into mild,moderate and severe.The results showed that the light could cause the decomposition of flue-cured tobacco pigment,the value of each color decreased and the fading of tobacco leaf.The larger the light intensity was,the more serious the fading.The flue-cured tobacco in purple soil was not faded easily than the flue-cured tobacco in sand soil.(2)The Nanxiong Xikou soil is of purple soil,showing alkaline,organic matter,total nitrogen,available copper,available zinc,and low effective iron content,with high content of available potassium and exchangeable calcium and magnesium.Shuikou in Nanxiong,Zhongshan and Fuchuan in Hezhou are sandy soil and muddy fields,and their exchangeable calcium and magnesium contents are low.The content of Ca,Mg and Mn in the roasted tobacco leaves in Xikou was significantly higher than that in other producing areas,and the content of copper and zinc was relatively low.However,the copper content in soil of Zhongshan in Hezhou was higher.After roasted,the chlorophyll content of tobacco leaf was less,and the carotenoid content was higher.Under indoor storage conditions,there was no significant change in the total sugar and potassium content of the tobacco leaves,and the contents of starch,total nitrogen,nicotine and NO3-were decreased,and the contents of reducing sugar and NO2-were increased.At the same storage time,the flue-cured tobacco pigment content and color difference at the Xiongxixikou mouth were lower,which was lower than that of other production areas.Through correlation analysis,it was found that soil p H,organic matter,available boron and exchangeable magnesium,and NO3-,NO2-and magnesium content in tobacco leaves had a greater effect on the fading of tobacco leaves after baking.(3)The optimization of production technology measures significantly increased soil p H,organic matter,available phosphorus,available potassium,and exchangeable magnesium,and significantly increased the pigment content of mature tobacco.Treated flue-cured tobacco leaf in Fuchuan was significantly higher than that of the control,and the optimization of production technology measures had no significant effect on the agronomic traits of flue-cured tobacco at maturing stage in Shuikou.The optimization of production technology measures significantly improved the production of flue-cured tobacco in Zhongshan and Fuchuan.The effect on the yield of flue-cured tobacco in Shuikou was not obvious,has significantly increased the proportion of finest smoke and medium-to-high smoke in each producing area.Therefore,the average price of flue-cured tobacco processed in each producing area was higher than that of the control.In the early stage of indoor preservation,the degradation rate of each pigment of flue-cured tobacco treated in the same production area was significantly lower than that of the control.Within 90 days of storage in the room,the color difference of the tobacco leaves was reduced.In the same production area,the reduction in the color difference of the treated flue-cured tobacco was lower than that of the control.This shows that the optimization of production technology measures can significantly improve the anti-fading ability of the flue-cured tobacco during storage,reduce the fading of flue-cured tobacco.