Obviously not all whiskies are worth storing, and many bottles wont last more than 6 months on your shelf. For anyone keeping whisky bottles for more than a few months Oxidisation needs to become your watch word else your expensive bottle of whisky will start to deteriorate.
There are a few avenues open to the whisky enthusiast who want’s to store their open whiskies for longer:
- Use an inert gas such as Argon, or a specialised combination mix to create a protective layer between your whisky and the air above
- Keep a supply of smaller bottles on hand and decant your whisky into these when the fill level dips
- Use vacuum pump stoppers to remove oxygen
- Use parafilm , or wax sealing to prevent oxidisation
What is Oxidisation?
Oxidisation refers to the process by which a substance combines with or chemically reacts with oxygen. On your bike or car this is called rust, in a glass of wine this creates acetic acid (vinegar) and in your whisky it does something else again. While oxidation is an important part of the cask maturation process it also changes whisky in a bottled whisky once opened, causing gradual shifts in flavor and aroma. If you have a number of bottles open at once then over time these will slowly deteriorate
Does whisky age in the bottle?
No whisky matures or ages only in contact with an oak* barrel. The continual aging of wine in a bottle** is related to tannin transformation – over time the tannins in a wine join together and form longer chains smoothing out the wine and imparting a silky smooth mouthfeel commonly associated with older reds. Assuming their is no cork/seal damage a still, unopened whisky will have virtually no contact with oxygen and so transform very little over time. Lacking the tannins, and organic material found within wine it will not continue to age, as such if your whisky was bottled at age 10, it will remain a 10 year old spirit.
*In Scotland only Oak barrels may be used however other countries are less stringent and historically other barrels such as chestnut were allowed.
**It should be noted that only a small number of wines actually benefit from bottle aging, the majority of wines produced are intended to be consumed quickly.
How long can you store whisky?
Once open a bottle of whisky, depending on fill level, can be stored for anywhere between 6 months and years. Generally the alcohol will begin to evaporate first making the whisky smother, then through ongoing changes with the active gas (oxygen) will transform the various flavour compounds in the whisky. In the short term this can improve the overall whisky, or rapidly deteriorate but the end result will always be the same, a lifeless, barely flavoured spirit. If you want to see this in miniature, leave a glass of whisky out overnight.
Storage Options Pro’s and Cons
There are a number of techniques used by whisky drinkers, most but of which will be covered here. Other tactics such as igniting the oxygen inside a bottle, or chilling the spirit are too dangerous, expensive or impractical to be worth recommendation.
Inert Gas for whisky preservation
Inert gas, that being any purified gas, such as argon, nitrogen or compound gas, which does not undergo chemical reaction is the gold standard of any serious collector/drinker. As these gasses are heavier than oxygen they will create a protective layer between the spirit and the air thus prevent oxidisation.
This is the gold standard of whisky preservation though bottles will require a top up after each pouring so this can become quite expensive.
Decanting whisky in to smaller bottles
A simpler solution can also be to decant your whisky into a smaller container. If you’ve ever done a distillery tour and taken a drivers dram, or swapped samples then you probably have a few smaller bottles already. These can be bought wholesale on Amazon, at a pinch if you’ve properly cleaned a beer bottle, and kept a few corks you can decant your whisky into this bottle. Less air in the bottle, and a smaller surface area means less oxidisation.
Ultimately this can be a nuisance as it means scanning through shelves of smaller bottles looking for a particular dram, not to mention the labeling but as a serious drinker you’re going to amass a collection of these anyway – and they’re very handy for new drinkers.
Vacuum pumps are a great idea in theory though somewhat less so in practice. By using a pump you essentially suck the oxygen from the bottle leaving the liquid in a vacuum.
If you’ve ever used these for your wine you’ll probably have noticed that they slow the deterioration rather than stopping it altogether. Unsurprising really as you won’t actually be able to remove all of the oxygen from the bottle, and oxygen is a gas so it will expand to fill the available space in the bottle. These will buy you time but not stop the process.
Sealing bottles with wax or parafilm
You want your alcohol to last as long as possible unfortunately alcohol evaporates at a varying
rate each year depending on temperature. I recently bought a bottle of Dallas Dhu at auction with a low fill level. This might not have been filled to the top of the neck, but this is the cost of evaporation.
Add to this that as alcohol evaporates, bacterial contamination can become an issue, transforming your whisky into a milky or cloudy liquids that is both unattractive to look at and unappealing to drink the appeal is easy to see.
Parafilm or wax are a great way of preventing anything from getting into your bottle, but they don’t do anything to remove the things already in there. As such they are a preservation tool, however if used on low fill level bottles they will not preserve it for long.