Studies On The Changes Of Chiefly Fragrant Precursor Contents And The Related Enzyme Activities Of Flue-cured Tobacco In The Maturity

The changes of chief fragrant precursor contents and the related enzyme activities, and the variation of that between different varieties, maturation and different stalk positions of flue-cured tobacco were studied. The experiments above were carried out to provide test basis for revealing both the synthetical mechanism and influencing factors of the fragrant precursor during the maturation process. This research was conducted with verities "K326" and "HongDa" as experimental materials. The advanced analytic technology of high performance liquid chromatography (HPLC) and gas chromatography (GC) were utilized to determine the contents of polyphenols, pigments, multiple organic acid, senior fatty acid, carbohydrates, nicotine, potassium, total nitrogen and activity of related enzymes at different maturation periods. The main results were indicated as follows:(1) During the maturation process, the content of chlorogenic acid and rutin increased gradually while that phenylalanine and tyrosine (the precursor of polyphenols) decreased. The chlorogenic acid and rutin contents had significantly negative correlation with aromatic amino acid during the maturation. The activity of PAL had positive correlation with chlorogenic acid and rutin. The activities of PPO and POD had significantly positive correlation with the contents of chlorogenic acid and rutin.(2) During the maturation process, the contents of chlorophyll and carotenoids decreased gradually, and the degradation speed of chlorophyll was faster than that of carotenoids. The degradation of chlorophyll had positive correlation with the activity of Chlase.(3) The content of sucrose had significantly negative correlation the activity of Ivr in the leaf of tobacco at the maturation process. After topping, the contents of solubility, nicotine and total nitrogen increased gradually, while the contents of starch and potassium decreased gradually(4) There existed significant variation of the contents of chief fragrant precursor and the activities of related enzymes in different varieties. The contents of chlorogenic acid, rutin, aromatic amino acid, chlorophyll, P-carotene and carbohydrate compounds in HongDa and the activities of PPO, PAL and Ivr were higher in variety of HongDa, while the contents of multiple organic acid, senior fatty acids, nicotine, total nitrogen, potassium and the activities of POD and Chlase were higher in variety of K326.(5) There existed significant variation of the contents of chief fragrant precursor and activities of related enzymes during different maturation period. The contents of polyphenols and carbohydrate compounds got to the peak at the proper maturity stage. The contents of pigments, potassium and aromatic amino acid decreased during the maturation process. There were no obvious difference of the contents of multiple organic acids and that of senior fatty acids. The contents of nicotine and total nitrogen increased with the maturation process. From unripe to proper maturity, the activities of PPO and POD increased, and subsequently the activities decreased. The activity of PAL increased while that of Chlase and Ivr decreased with the maturation process.(6) There existed significant variation of the contents of chief fragrant precursor and activities of related enzymes in leaf of tobacco at different stalk positions. With the stalk position increasing, the contents of chlorogenic acids, rutin, nicotine, total nitrogen and the activities of POD and PAL in leaf increased gradually, while that of pigments (P-carotene excluded), aromatic amino acid , multiple organic acids, senior fatty acids, potassium, Chlase and Ivr decreased. The content of carbohydrate is the highest in middle leaf. The activity PPO was the highest in upper leaf, that in lower leaf took the second place, and that in middle leaf was the lowest.