Studies On The Physiological And Biochemical Changes During Curing Process And Harvesting Methods Of Sun-Cured Red Tobacco

Studies on the physiological and biochemical changes during curing process and harvesting methods of the main variety Xiaohuaqing of sun-cured red tobacco had been conducted in Fenghuang county of Hunan province from 2004 to 2005.The results showed that:1 .The water content lost slowly at the beginning of curing,then fast until the end of curing. With the loss of water content, endopeptidase activity and free amino acid content increased. It was high significant correlation between endopeptidase activity and dehydrating rate ( Upper leaves:r=-0.9203^** ;Cutter leaves:r =-0.9024^**;Lug leaves:r=-0.9159^**) .It was also significant or high significant correlation between free amino acid content and endopeptidase activity. The correlation indexs were 0.8664, 0.9534 and 0.9700. So endopeptidase activity played an important role in the forming and increasing of free amino acid and the proper loss of water content could enhance the activity of endopeptidase.2.The content of total nitrogen and nicotine had no obvious change during the curing. Total nitrogen content increased a little and nicotine content reduced slightly. The content of NO₃^- decreased continually, the scope was lug leaves > cutter leaves> upper leaves. The content of NO₂^- increased and then reduced. The top content in upper and cutter leaves was 8 days,while 6 days in lug leaves after harvesting. As a whole the content of NO₂^- increased obviously during the curing process. 3.The starch was decomposed sharply in the first 2 days and then had no obvious change. The content of total sugar decreased continually in the curing process. Amylase activity declined with the loss of water. The relative water loss content and amylase activity in cutter leaves were highly significant negative-correlation at 1% level. The level of significance in upper and lug leaves reached negative correlation at 5% level. It showed that dehydrating rate had a full impact on amylase activity. 4. Total phenols content increased,but it changed differently in three positions. The content of total phenols in upper and cutter leaves increased rapidly in the first 4 days and slowly during 4-8 days, and then reduced. The content of total phenols increased slowly during the whole curing process. The contents of K⁺ and Cl^- changed...