Dynamic Changes Of Substance Content Of Cigar Leaves During Air-curing

This experiments were conducted in Daquankeng Village,Shifang City,Sichuan Province in 2018-2020.Using Dexue No.1 and Shiyan No.1 as the test materials,the changes of polyphenols metabolism,plastid pigment metabolism,carbon and nitrogen metabolism,non-volatile organic acid metabolism and related enzyme activities in different positions of cigar leaves during airing were studied,and the correlation analyses were carried out.The results are as follows:1.With the process of air-curing,the polyphenols contents showed cutters>low leaf>upper leaf.The chlorogenic acid and rutin contents showed first increased and then decreased,and the content of scopoletin showed a downward trend during airing.The content of plastid pigments showed downward trend,which was upper leaf>cutters>lower leaf,and the content of Dexue No.1 were higher.The activity of lipoxygenase,phenylalanine ammonia-lyase,polyphenol oxidase and peroxidase showed a single peak curve,but the time to peak were different.The positions of enzymes activity showed upper leaf>cutters>lower leaf.Correlation analysis showed that lipoxygenase activity was significantly positively correlated with rutin content at lower leaf.Polyphenol oxidase activity was significantly positively correlated with polyphenols and plastid pigments contents.Phenylalanine ammonia-lyase activity was significantly negatively correlated with chlorogenic acid content in all positions during air-curing.The activity of peroxidase and the content of polyphenols and plastid pigments were not significantly correlated,but it and other three enzymes reached significant levels in all position.2.The content of total sugar,reducing sugar,starch,total nitrogen and protein showed a downward trend in all positions of cigar tobacco leaves during air-curing,but the contents of acid and nicotine increased first and then decreased.The total sugar and reducing sugar contents showed cutters>upper leaf>lower leaf,but the starch content of upper leaves was higher than other positions.The nitrogen compound content shower upper leaf>cutters>lower leaf.During air-curing,the activities of amylase and neutral invertase showed first increased and then decreased in all positions of cigar tobacco leaves,while the activities of nitrate reductase and glutamine synthetase showed a downward trend.The varieties of chemical composition content and enzymes activity showed Shiyan No.1>Dexue No.1.Correlation analysis showed that neutral invertase activity was significantly negatively correlated with total sugar and reducing sugar contens in all positions,but it was significantly positively correlated with the content of starch.The activity of amylase extremely significantly positively correlated with carbohydrates contents.The activity of nitrate reductase extremely significantly positively correlated with total nitrogen and protein contents.The activity of glutamine synthetase significantly positively correlated with nitrogen compounds contents.3.With the process of air-curing,the content of malic acid showed a downward trend in all positions,but the content of citric acid,malonic acid and oxalic acid showed an upward trend.The activity of malate dehydrogenase showed increased first and then decreased,the activity of citrate synthase increased,while the activity of succinate dehydrogenase showed a downward trend.The varieties of malic acid,citric acid,malonic acid,oxalic acid contents and related enzyme activities showed Shiyan No.1>Dexue No.1.The positions of four non-volatile organic acids contents showed lower leaf>cutters>upper leaf.The activies of malate dehydrogenase and succinate dehydrogenase showed upper leaf>cutters>lower leaf,but citrate synthase activity showed lower leaf>cutters>upper leaf.Correlation analysis of tobacco non-volatile organic acid content and related enzyme activities showed that malate dehydrogenase activity was extremely significantly negatively correlated with malic acid contents.Succinate dehydrogenase activity was extremely significantly positively correlated with malic acid contents,and was extremely significantly negatively correlated with citric acid and malonic acid contents.Citrate synthase activity was extremely significantly negatively correlated with malic acid contents,and was extremely significantly positively correlated with citric acid and malonic acid contents.4.By comparing the content of conventional chemical components for cigar leaves of different positions after air-curing,the content of starch and protein were the lowest in the cutters of Dexue No.1 and the highest in the upper leaf of Shiyan No.1.The content of total sugar and reducing sugar were the highest in the upper leaf of Shiyan No.1 and the lowest in the lower leaf of Dexue No.1.The content of total nitrogen and nicotine were increased with the increase of positions,but there was no significant difference between positions.The potassium to chloride ratio of Dexue No.1 was higher than Shiyan No.1 in all positions,and it was highest in the lower leaves,and the ratio of nitrogen to alkali was closest to 1:1 in the cutters.In summary,the chemical components were coordinated in the cutters of Dexue No.l.5.By comparing the physical characteristics for cigar leaves of different positions after air-curing,the leaf weight and leaf thickness were highest in the upper leaf,and the pull and equilibrium moisture content were highest in the cutters,and the ratio of stem was lowest.The varieties of leaf weight,leaf thickness and stem ratio showed Shiyan No.1>Dexue No.1.Sensory quality showed that the quality of aroma,volume of aroma,sweetness and total score increased first and then decreased with the increase of the positions after air-curing,and the sensirt quality were better in the cutters.