Effects Of Three Flue-curing Technology On Physiological And Biochemical Changes And Quality Of Flue-cured Tobacco Leaves In Summer Drought

In order to of analysis the effects on the physiological and biochemical changes of tobacco leaves in curing processes and the quality of cured leaves of flue-cured tobacco in the summer drought,three mothed(conventional curing 1,conventional curing 2 and braising-curing)were set up to studied in Yinjiang,Tongren,the results showed:1.The physiological and biochemical changes of tobacco leaves during the three curing processes are as follows(1)Moisture: The water loss rate shows a slow-fast-slow change trend;as the difference between dry and wet conditions decreases,the water loss rate gradually decreases in the yellowing period(the water loss is T3<T2<T1),and increased gradually in leaf-drying stage and the stem-drying stage(water loss was T1 < T2 < T3).(2)Pigment: The degradation rate of the pigment is in a fast-slow-slow downward trend;as the difference between dry and wet conditions decreases,the degradation rate of chlorophyll gradually decreases in the early stage of yellowing,and gradually increases in the middle to late yellowing period and the leaf-drying period.Carotenoid and chlorophyll show similar laws.(3)SPAD value:The decrease rate of SPAD value shows a fast-slow-slower change trend.As the dry-wet difference decreases,the SPAD value decline rate gradually decreases in the early yellowing stage,gradually increases from the middle to the late yellowing stage,and fluctuates slowly after the stem-drying period gradually increases.(4)Enzyme activity:α-amylase activity has a bimodal curve,in which the first peak appears in the middle yellowing stage,and the second peak appears in the late yellowing stage to the early stage of leaf-drying period;With the decrease of the difference between dry and wet,the time lag of α-amylase activity reaching the first peak,long duration,and high enzyme activity,while the time lag of reaching the second peak,the same duration,and high enzyme activity.The SOD and POD activity were single peak curve,and single peak appeared in the middle of yellowing period;As the difference between dry and wet decreases,the later the peaks of SOD and POD appear,the higher the enzyme activity.The PPO activity showed a bimodal curve,in which the first peak appeared in the middle yellowing stage,and the second peak appeared in the late yellowing stage;With the decrease of dry wet difference,the later the first peak of PPO appeared,the higher the enzyme activity was,and the later the second peak appeared,the lower the enzyme activity was.(5)Chemical composition: The degradation rate of starch is fast-slow-slower-slowest,In addition,the changing regularity of reducing sugar and total sugar was obviously related to the changing regularity of starch;As the dry-wet difference decreases,the starch degradation rate gradually decreases from the early stage of yellowing to the middle stage of yellowing,and gradually increases in the later stage of yellowing,The leaf-drying period first decreases and then increases,and the stem-drying period gradually decreases.The decrease rates of nicotine,total nitrogen and protein all showed a fast-slow-slower trend;With the decrease of dry wet difference,the protein degradation rate first increased and then decreased in the yellowing stage,and gradually increased in the leaf-drying stage,while the opposite trend was observed in the stem-drying stage and yellowing stage.The increasing rate of potassium and petroleum ether extracts showed a fast-slow-slower trend;With the decrease of dry wet difference,the increasing rate of potassium increased gradually in yellowing stage,increased first and then decreased in leaf-drying stage,and decreased gradually in stem-drying stage.The increase of MDA showed a change trend of less-more-less;With the decrease of dry and wet difference,the increment of MDA decreased first and then increased from the early yellowing stage to the middle yellowing stage,decreased from the late yellowing stage to the early leaf-drying stage,and increased from the middle leaf-drying stage to the late leaf-drying stage.The total phenol content showed a gradually increasing trend;As the dry-wet difference decreases,the increasing rate of total phenols first increases and then decreases during the yellowing period,gradually increases during the leaf-drying period,and decreases first and then increases during the leaf-drying period.2.Effects of three curing processes on the quality of flue-cured tobacco leaves(1)The results showed that the first-class tobacco rate,orange yellow tobacco rate and average price of the three curing processes were all in the order of T3 > T2 > T1,while the variegated tobacco rate was on the contrary.That is,the grade quality of braising-curing is better than conventional curing.(2)Chemical composition: Except that the total nitrogen,sugar alkali ratio and total sugar to protein ratio of braising-curing cured tobacco were lower or higher than those of high-quality tobacco,other chemical indexes met the requirements of high-quality tobacco,while other chemical indexes of conventional curing tobacco were higher or lower than those of high-quality tobacco(carbohydrate,total nitrogen,petroleum ether extract and total sugar to protein ratioe of T1,starch,total nitrogen,sugar alkali ratio and total sugar to protein ratio of T2).that is,the content of braising-curing cured tobacco the overall chemical composition and coordination were good.(3)Judging from the total score of the smoking quality,the T3>T2>T1.In conclusion,no matter which curing technology is used,the physiological and biochemical changes during curing process are basically the same,but there are some differences in physiological and biochemical changes and tobacco quality at different stages.Generally speaking,the braising-curing is more conducive to the physiological and biochemical changes of flue-cured tobacco and the improvement of the quality of flue-cured tobacco,the conventional curing 2 is the second,and the conventional curing 1 is slightly worse.