| The paper preliminary explored the curing and aging characteristics of “Yuyan 11”, and also studied the influences of different curing processes,harvest maturities and aging time on curing efficiency and cured-leaves’ quality, the results showed that:On the basis of “Black Box Text” results, the change of water content and related enzyme activities during curing, “Yuyan 11” indicated a character of turning yellow quickly and losing water slowly, easy but not resistant to cure. During curing, “Yuyan 11” had a relative high speed of chlorophyll degradation. Each treatmen had few content of chlorophyll after 36 hours, and there is no significant difference among treatments. The water content of tobacco leaf decreased slowly before 48 hours in each treatment, no significant difference was founded among treatments; But significant difference were existed in treatments during 48-72 hours. This lead to a significant difference of PPO activity in the period of turning yellow to fixing color in tobacco leaves, high PPO activity lead to a large rate of hanging the ash of tobacco leaves, and the low PPO activity was opposite. Using high temperature to turn yellow, and extend 10-15 hours of yellow turning period can significantly decreased the water content in tobacco leaf,which resulted in a decline of PPO activity and keep them in a normal range during the period of turning yellow to fixing color, can decreased the rate of hanging ash in tobacco leaves.Effects of different maturities(unripe, ripe and overripe)of tobacco on the changes in the content of water, PPO activity,polyphenols of Yu Yan 11(a new kind of flue-cured tobacco) during curing process and the correlation between indexes were investigated. The results indicated that tendency of the changes in the contents of water, PPO activity,total polyphenols in three maturity levels are similar: Water content of tobacco leaf gradually reduced; PPO activity slightly declined, then rapidly increased and finally sharply declined. The changes in the rutin content of unripe and overripe tobacco leaves were similar. The trend of rutin content in mature tobacco leaf was “decreased-increased-decreased-increased” slightly. The content of scopoletin in three maturities increased as a whole. During the sensitive period in Enzymatic Browning Reaction( 48~66h in the curing process), overripe tobacco had the lowest content of water and PPO activity, the contents of total polyphenols and chlorogenic acid were slightly lower than in mature tobacco. The water and PPO activity contents of mature tobacco were lower than in immature tobacco leaf and higher than in over mature tobacco leaf. The contents of total polyphenols and chlorogenic acid in mature tobacco were highest. The water and PPO activity contents of immature tobacco were highest; the contents of total polyphenols and chlorogenic acid in it were lowest. The contents difference of rutin and scopoletin among three maturities has no significant regularity. During 48~66h period,there was a significant negative correlation between the change of PPO activity and the accumulate speed of polyphenols: Unripe treatment reached an extremely significant level, mature treatment reached a significant level, and overripe treatment reached an insignificant level. It suggested that high PPO activity reduced the accumulation of polyphenols in immature and mature tobacco leaf significantly, and low PPO activity effected on the accumulation of polyphenols in overripe tobacco insignificantly. Appropriately improving the maturity of harvested flue-cured tobacco, can promote the tobacco leaf water loss effectively, so as to reduce the PPO activity during the curing process,it is beneficial to prevent browning in tobacco leaves, thus improve the appearance and intrinsic quality of cured tobacco leaf.Through 21 months of natural aging, routine chemical components and neutral aroma substances of Henan and Guizhou tobacco leaves were both changed significantly. Total sugar, reducing sugar and nicotine content were significantly reduced, and the total nitrogen and protein content changed little. The degradation product content of cembranoid diterpenes, phenylalanine derivatives and carotenoids increased significantly, the brown reaction products content basically remain unchanged, and the neophytadiene content declined slightly. The experiment showed that at aging months of 15 or 18, the content of routine chemical components and aroma substances were stable both in two areas, but the content of total sugar and reducing sugar declined relatively obviously, this may be due to tobacco leaf metabolism consumption. “Yuyan 11” The degradation product content of cembranoid diterpenes and carotenoids were significantly higher than local varieties. According to the result of smoking evaluation, with the increase of aging time, flue gas quality improved obviously, reached the peak at the age of 18 or 21 months. |
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