Here is a reliable tobacco curing technique. I have found it produces great results, and is well suited to the small scale tobacco gardener. It takes time, vigilance and patience, but is well worth the effort.
Tobacco curing is really fermentation. When the leaves are harvested, they begin an amazing alchemical process of complex biosynthesis of residual compounds that produce different qualities including distinctive flavor and aroma.
The leaves are hung or laid on screens to dry when harvested. Leaves are stacked together as they dry to prevent them from loosing too much too fast. Leaves will often dry more evenly and less spotty when stacked in piles. Make stacks with a large lower leaf or two on the bottom of each pile to make it easy to bundle up whole stacks for curing.
The key to curing tobacco is containment. Traditional native methods vary from wrapping in corn husks or other large leaves, to packing into logs or tree stumps. I prefer a means to contain tobacco leaf for curing which makes little or no contribution to the natural resulting distinctive flavor and aroma. I use larger wide mouth apothecary type glass jars. The jars should not be packed so tightly that leaves at the core could not be easily pulled out. The leaves need a little space to breath and transpire as fermentation perks along.
Fermentation begins when lids are closed on jars placed in a warm dark place. I keep my curing jars in a kitchen cabinet. The jars are easily accessible to check regularly. The closed cabinets keep things in the dark, and the temperature stays just a little warmer than room temperature. These are ideal conditions for tobacco to cure naturally. It takes longer than modern kiln techniques, but it is well worth the wait.
(Picture of Mopan, Samsun, Yumbo curing jars)
Excess leaf moisture will evaporate during the first week or two of fermentation in the closed jars. Some of the leaf stems hold on to moisture longer than the leaf tissues. Much of this moisture is absorbed by the other leaves in the jar, so equalizing moisture content throughout all the leaves is the goal. When moisture condenses inside the jar it needs to evaporate more quickly than the leaves can absorb. The jars must be checked daily and lids removed when condensation appears. It helps to move the core leaves a little by pulling their stems a bit - sort of loosen up the stack and encourage breathing space for transpiration. Replace the lid when condensation completely evaporates. It will take several hours. Just remember to replace lids before going to bed or the entire jar may dry out too much overnight.
The jars should be condensation free within the second week. At this point, the leaves in the jars have equalized moisture throughout. Leave the jars closed and undisturbed for one month. During this difficult wait, the only task is to check the jars regularly for evidence of mold. If mold appears, open the jar and remove the molded leaves, and allow the jar to vent a couple of hours before replacing the lid. Keep a close check for mold reappearance.
After one month undisturbed, each jar is checked for color and aroma. The core leaves are moved and some other leaves should also be moved a little to encourage breathing space for transpiration.
There should be a distinct tobacco aroma to the leaf, not grassy or sour. Off aromas are probably just evidence of incomplete fermentation, but may also indicate undetected mold. Check visibly as you move the leaves around. Vent suspect jars for several hours, then replace lids for another month. Yes, a second month undisturbed is needed to give plenty of time for leaf fermentation to finish naturally. Some varieties may take a little longer. If the aroma is not noticeably better after the second month, leave it another couple of weeks and check again.
(picture of cured Mopan, Samsun, Yumbo fresh from the jars)
Fermentation is complete by the end of the second month in jars. When the jars are opened the distinctive tobacco aroma should be noticeably richer and fuller, a somewhat earthy scent. At this point, the tobacco leaf is cured enough to be removed from their jars and processed for aging. I age in pint and half pint glass jars. Tobacco quality improves after two months, six months, one year, two years, four years and so on. I have never been able to hold on to any of my own tobacco longer to be able to attest to improvements beyond four years.
This jar curing technique produces exceptionally flavorful tobacco. By curing stacks of leaves, many come out of the jar in pristine condition for wrappers. For the small scale home tobacco gardener, this jar method is really ideal.
(if someone can tell me how to upload jpeg. I will post a couple of pictures with this)