Good question about oxygen. In a pilone the fermentation is faster in the middle where it is warmer and more moist, but there's less air. There is air, but there appears to be a hierarchy favouring moisture. Putting dry tobacco in a pure oxygen atmosphere doesn't do anything. Also, curing and aging research I've read in the past seems to support that they involve various biological process that are dependent on the complex chemical and enzymatic environ of the leaf itself. Aside from respiration, which leaf is not doing anymore, as respiration builds carbohydrates, most other oxygen involved processes within plants involve enzymes breaking the water molecule to utilize oxygen, ie. hydrolysis.Fermenting in vacuum sealed bags or just storing it like that? Oxygen is needed for the tobacco to do it's work right?
Thank you for your input, but it is quite clear even from the source you posted that fermentation is not "simply pressure" that causes fermentation. Microbes do the bulk of the work. You can't see the little tykes so I get why you might miss it.https://www.cigarslover.com/en/the-fermentation-of-tobacco-leaves/ This is for cigars not I know fermentation happens just leaving leaves in a bail.
It could seem that way since there are so many ways of treating tobacco, processing it, storing it and preparing it for use. Fermentation itself is a confusing process too which maybe got mixed up with the practice of pressing and/or piling somewhere along the line. It seems clear to me though from the well referenced, tested and repeatable practices documented here on this site that pressure is definitely not the only factor acting on fermentation. I still have much to learn here.Fermenting on smoking tobacco is simply pressure on the leaf when the juices meld together. Tobacco in a bale ferments. It doesn't have to be a lot of pressure just stacking it together in a pile with a book on top will allow the leaf to ferment.