Hi Coolbreeze,

Tins are vacuum sealed too but short of very expensive equipment you won't remove all oxygen with a household sealer nor a manufacturer sealed tin (that seal similarly to a mason jar). I've read that the changes in taste are made by aerobic bacteria but I don't know the source of that claim nor if it's true.

At intervals over the last 25 years I've been opening tins from the late 1980s (mostly one brand) and have found that the changes are consistent with tobaccos marrying rather than bacterial activity. If 'ageing' is the gradual (usually) subtle change in flavor profile then that too is consistent with marrying. Marrying is the acceptance of characteristics (flavor, aroma) from the other leaf in a mixture (or cigar).

Dry tobacco doesn't age well, (if at all), so I assume that moisture must be an agent of change. Virginia and Carolina do not easily flavor or take on the characteristics of other leaf. Both of these points support the idea that it is extended marrying that is actually what is transpiring. This explains why latakia loses potency and Virginia ages best (especially with extended ageing). If your hope is to achieve a smoother more nuanced version of the original mixture then understand how time in a vacuum sealed package affects what type of leaf because we shouldn't be warehousing latakia mixtures in the hopes that they will marry into something similar but superior to the original only to find that after 15 years it's just a muddled reminder of what it was.

A lack of oxygen would help to inhibit mold but most manufacturers use some form of anti-fungal. Long ago, Rattray Marlin Flake was notorious for molding (1980s and before) but it was still worth the effort .

Pete