Relationships of Starch Content and Amylase Activity to Temperature and Humidity during Curing Process

The relationships of the changes of amylase activity and content of starch in tobacco leaves to temperature, humidity and duration during curing were studied with two KY-2 automatic electric-heated ovens.The results indicated that there were two peaks of amylase activity, one in the middle to late stage of yellowing and the other in the late stage of color fixing to stem drying stage, the majority of starch was degraded when the temperature was in the range of 38-44℃, the leaves of different stalk positions followed the same rule.Therefore, the temperature of yellowing stage should be started from 35℃, before it reached 42℃the difference between dry and wet bulbs should be widened to 3℃ (especially for cutters), and then narrowed appropriately to maintain proper humidity (especially for upper leaf), the curing time should be suitably extended according to the changes of tobacco leaves when the temperature was below 44℃ to keep the activity of amylase and promote the degradation of starch.