A comparative chemical study of flue-curing and shade-curing of virginia tobacco
In order to study the biochemical peculiarities of flue-curing and air-curing a flue-cured type of leaf was subjected to both the systems of curing.
During the first 40 hours which corresponded to the yellowing stage in flue-curing, the leaf was at a higher temperature and humidity in flue-curing than in shade-curing.
This resulted in hastening of chemical reactions in flue-curing as compared to shade-curing. The leaf was completely yellow at the end of 40 hours in flue-curing, while it was only 75% yellow at the end of 123 hours in shade-curing. Also there was greater hydrolysis of starch, more production of sugars and finally greater loss of solids in flue-curing than in shade-curing.
The contribution of carbohydrates to respiratory losses in the early stages was more in flue-curing than in shade-curing, showing thereby that more of other constituents than carbohydrates contributed to these losses in shade-curing.
Probably because of this there was considerable loss of nitrogen under shade-curing while the changes in this constituent during flue-curing were insignificant.
The present study thus tends to show two facts.
1. Due to higher temperature in flue-curing the chemical reactions are hastened as compared with shade-curing.
2. Even in flue-cured leaf, some reactions characteristic of air-curing occur, if it is subjected to air-curing.