| Aroma matter of flue—cured tobacco is accumulated in field,but it is displayed through curing and highly different in different curing treatment.so it has important meaning to study the influence of different curing treatment to aroma matter. This experiment studied the influence of different curing treatment to aroma matter and physiological and biochemical characteristics of tobacco with electric-heated flue-curing barn, The main results are as follows:1.During the flue-curing process,the water loss rate of tobacco leaf is slow in 0—24 hours.the average of water loss rate is 0.16% per hour, the water loss rate of tobacco leaf is quick in 24—72 hours.the average of water loss rate is 0.99% per hour,the water loss rate is faster in high temperature yellowing treatment than that in low temperature yellowing treatment.In the same temperature condition, the water loss rate was low humidity(relative humidity 75~70%)>middle humidity(relative humidity 85~80%)>high humidity(relative humidity 95~90%).2.The activitie of POD showed downtrend under different temperature and humidity treatments, the activities of POD was higher in low temperature middle humidity and high temperature middle humidity treatment. The activities of PPO showed"rise~reduce~rise~ reduce"in six temperature and humidity treatments,it was lower under low temperature low humidity, low temperature middle humidity and high temperature low humidity treatment.3.The activitie of PAL showed the same change trend under different temperature and humidity treatments, during the early stage of curing(0-36h), the activitie of PAL was descreased,during 36h to 60h the activitie of PAL was increased, reached its peak at 60h, then declined. Under high temperature treatment, the enzyme activities was higher in the early stage of curing and was lower in the later stage of curing.But it was contrary under low temperature treatment.During 72h the activitie of PAL was higher under low temperature low humidity and low temperature middle humidity treatment.4.The activitie of Lox was acended during 0-36h under different temperature and humidity treatments,it reached the peak at 36h under low temperature low humidity, high temperature low humidity and high temperature middle humidity treatment,then decreased. The activitie of Lox reached the peak at 48h under low temperature middle humidity treatment, low temperature high humidity treatment and high temperature high humidity treatment,then decreased. During 72h the activitie of Lox was higher under low temperature middle humidity, low temperature high humidity and high temperature high humidity treatment.5.Degradation rule of chlorophyll was"slow-fast-slow". The chlorophyll declined rapidly under low temperature low humidity, low temperature middle humidity and high temperature middle humidity treatment.Theβ-carotene showed the same change trend under different temperature and humidity treatments,it had a little decrease during 0-12h,then reduced rapidly, tended to be stable ofter 48h. The degradation amount ofβ-carotene was:low temperature middle humidity(80.25%)>low temperature low humidity(78.49%)>high temperature middle humidity(71.29%)>high temperature high humidity(70.08%)>low temperature high humidity(69.84%)>high temperature low humidity(66.41%).The lutein, neoxanthin and violaxanthin showed the same change trend under different temperature and humidity treatments, it had a little decrease during 0-24h, then reduced rapidly, tended to be stable ofter 48h. The amount of the three colorant decomposed under low temperature low humidity treatment was the highest,then was under low temperature middle humidity treatment.6.There is great difference of colorant in cured tobacco leaf under different temperature and humidity treatments. The amount of theβ-carotene under low temperature middle humidity treatment was the lowest, is only half of that under high temperature middle humidity treatment, it showed no significant difference in other treatment. The amount of lutein, neoxanthin and violaxanthin was lower under low temperature low humidity and low temperature middle humidity treatment.7.the contents of neutral aroma components were different in cured tobacco leaf under different temperature and humidity treatments.low temperature middle humidity(2143.43μg/g)>low temperature low humidity(1896.91μg/g)>low temperature high humidity ( 1661.75μg/g ) > high temperature low humidity(1645.09μg/g)>high temperature high humidity(1534.30μg/g)>high temperature middle humidity(1373.2μg/g).The physical properties of cured tobacco leaf was best under low temperature and middle humidity yellowing condition, every index was within the range of the suitable one; The content of nicotine , total nitrogen and starch in tobacco leaf were reduced, The content of total sugar,reducing sugar,K were improved, the chemical composition was harmonized.8.Under the curing condition of tobacco leaves fixing-color at slow speed,the activitie of POD,PPO,PAL and LOX was higher,and the amount of theβ-carotene, lutein, neoxanthin and violaxanthin decomposed was higher.9.The amount of lutein, neoxanthin and violaxanthin was lower under the curing condition of tobacco leaves fixing-color at slow speed,the amount of the colorant decomposed fully the curing condition of tobacco leaves fixing-color at slow speed.10.The amount of Maillard reaction products in cured tobacco leaves had little difference under fixing-color treatment,but the amount of neoplytadiene,products degraded by carotenoid,products of aromatic amino acid metabolism,products degraded by cembrane in cured tobacco leaves was higher under the curing condition of tobacco leaves fixing-color at slow speed.The physical properties of cured tobacco leaf was better under the curing condition of tobacco leaves fixing-color at slow speed, every index was within the range of the suitable one; The content of nicotine , total nitrogen and starch in tobacco leaf were reduced, The content of total sugar,reducing sugar,K were improved, the chemical composition was harmonized. |
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