Those Pesky Non-polar Molecules

5th April, 2005: Posted by glpease in Tobacco, Science

I’ve occasionally written about the difference between keeping moisture contained with pipe tobacco, and keeping all those lovely volatile organic, non-polar molecules that are responsible for flavour and aroma locked up. Tins, glass jars, multi-layer, high-barrier foil bags and so on do an excellent job at both, while most plastics, including freezer bags, “Seal-a-Meal” type vacuum bags, will do a fine job of keeping moisture in, but will not support proper aging, as they are permeable, in varying degrees, to the “good stuff.” But, just how important is it to store the tobaccos you enjoy smoking in a tightly closed environment?

This, of course, depends on a few factors. Young, blended tobacco is actually fairly stable. The stuff has been hydrated and dried several times before being blended, and then, conditioned for tinning after blending. Certainly, it’s lost a lot to the angel’s share by the time it’s incarcerated, but one could easily argue that most, if not all of what’s dissipated is GOOD for the final product. For instance, part of the initial aging process results in the synthesis of ammonia; anaerobic bacteria are present that fix nitrogen compounds, liberating ammonia as their byproduct. It’s good to air out young leaf before it’s processed for this reason. But, by the time the tobacco gets to the blending stage, this process should be complete. If you open a tin and get a strong whiff of ammonia, someone upstream didn’t do their job fully. The same is even more true with cigars, of course, which is why I can’t stand cello wrappers, and will always remove them and let a cigar air out in my humidor for a couple weeks before it’s really ready to smoke. But, that’s another subject…

By the time tobaccos are blended, they’ve been aged, but once the finished product is put in the tin, things begin to change in rather different ways. This is where the real “aging” that we like to talk about begins. The organic byproducts of this aging, and I’m really talking about the tin sitting around for much longer than a few weeks, are volatile , often delicate, and can be wildly fugitive if not sealed in tightly. This is why my favourite “sniff and smoke” from an ancient tin is always the first, right after it’s opened. (Anecdote will follow…)

So, if the tin has aged six months or more, and you like what you smell and taste when you open it, at the very least, put a double-layer of aluminium foil over the top before replacing the plastic overcap. This will help to prevent those wonderful, ephemeral molecules from walking right through the plastic cap. Better still, as immediately as possible, seal the contents of that tin in a jelly jar or similar. This will go a long way toward keeping in the goodness, only letting out a share when you the lid is removed. Keeping the container in a cool place is also a good idea.

Another thing to consider when choosing a storage method is how long you tend to keep an opened tin of tobacco around. If you smoke it within a week (a tin a week - that’s all we ask!), it probably doesn’t make a great of difference, unless you store the tobacco under hot conditions, accelerating the dissipation of both moisture and volatile aromatic components. Again, cool is always better, both for cellaring and for keeping opened tins. Don’t, however, keep it in the fridge, which is actually a very dry environment, and the freezer is the worst place for your beloved stash, as ice will form, and moisture will sublimate, resulting in a less than ideal texture of the tobacco.

For short-term storage, a little square of foil is cheap insurance, and just quirky enough to add a little extra charm to the presentation of open tins. Jars are, of course, better, but the trouble - cleaning them, labeling them, transferring the tobacco, and ensuring they won’t meet their doom by contacting a hard surface at the behest of gravity - keeps me from using them for any but the most precious of open tins. Now, on to the anecdote.

Last night, I opened a tin of the blend I did for the NASPC show last year. It was tinned on 1st September, so it’s been aging for a scant six months plus a little. The last time I’d opened one of these was at just about the one month mark. The difference between freshly blended and one month surprised me, as it was more significant than expected. The difference between one month and six, however, is remarkable.

Upon pulling the top, a beautiful, fruity aroma greeted me - peaches, pears, apples, all tree ripened and succulent. Then, in waves, other things presented. Angel food cake. Ripe figs. A distant campfire. (Makes sense. There’s a tiny bit of Latakia in there.) Deeper still, a hint of acidity; not lemony, but more like a crisp, dry Sauvingon Blanc. I filled a pipe, and enjoyed the last bowl of the day. Wonderful. I’m excited to see how this one changes over the next six months, the next year, the next five.

I neglected to do the “foil thang,” and just put the plastic lid back on. This morning, as I type this and puff on a bowl, some of the more subtle flavours and aromas from that tin have already gone missing. It’s still a pleasant smoke, not hugely different from last night’s, but it is a little changed.

To be fair, some pipesters actually prefer to “air out” their tobaccos a bit. Just as I love the first bowl best, others may prefer the last. In fact, Charles Rattray, in his “Disquisition for the Pipe Smoker,” wrote that the last bowl from his tins would be the best. (I’ve known smokers that preferred their tobaccos as dry as dessicated mummy dust. To each his own! For more on that subject have a look at Tobacco Reanimation - Bringing it Back to Life.)

In the discussion of whether or not to foil your tins, put your tobacco in jars or store it in shoe boxes, personal taste prevails. Try it both ways, and see what works best for you. In the end, your own experiences will be the final arbiter of what is “right” for you.