After being harvested and cured, tobacco is not fully stabilized and can not be kept long at this stage. It must be fermented. Fermentation is a complex process but in simple terms one can say that it is a transformation of the chemical components by oxydation.
Why is tobacco fermented?
Mainly because fermentation makes the tobacco lose its raw and green taste that nobody would really like.
Who can ferment tobacco?
It is easy to grow a few tobacco plants in your backyard if you like gardening. But if you want to process it for smoking, you'll have to ferment it. If not, its taste would be unpleasant. To properly ferment your tobacco, you need either large quantities in the hundreds of pounds to build a bulk for natural process or you would need to acquire expensive equipment for an artificial fermentation. We recommend that you grow petunias (decorative tobacco plants, with lots of colorful blossoms) and buy cigars to enjoy your smoke while working on your beautiful garden.
How is tobacco fermented?
To process a natural fermentation, tobacco is piled up. The weight and the natural humidity content allow the fermentation to start in the middle of the pile. The temperature goes up. When the targeted temperature is reached, the pile is broken and rebuilt, the outside tobacco going inside and vice versa. And that as many times as is necessary, until the whole pile is properly fermented. Some heavy tobaccos can need up to six turnings. It lasts months to ferment them correctly.
Fermentation and Quality
Each type of tobacco has its own fermentation procedure. The main factors to define the process are the texture of the material and the utilization of the tobacco afterwards. Light wrappers and full bodied fillers are not fermented in the same way.
Fermentation and Aging
Fermentation is a natural transformation of the chemical components that stabilizes the raw material. The process is rather deep and quite fast. When well fermented, a tobacco can be stored for years without damage. Aging is a slow natural evolution , during which the tobacco is going to improve its characteristics and lose its " green " taste. Once blended in a cigar, the tobacco deserves a new period of aging in order to reach a good balance between the blend components.
Fermentation and Temperature
Humid tobacco leaves put in pile are going to start fermenting giving out heat. The control of the temperature inside the pile is a key factor of success. If the temperature goes too high, the tobacco will be cooked and deteriorated. Each type of tobacco has its own optimal temperature. When it is reached, the pile has to be opened to stop the heating process and a new pile is built with cooled down tobacco. The outside tobaccos go inside and vice-versa. As an example, a dark air cured tobacco accepts a temperature up to about 130ºF. Disaster for this leaf can start at 140ºF.