An Experiment in Maturation

Experiment in Maturation


The Post-Finishing Process

quarter cask
Your author is delighted to be just about able to brandish an empty one of these.

In August this year, you may remember that I wrote about our set of newly delivered quarter casks (or ‘octaves’), former guardians of Pedro Ximenez sherry, which we had thought about filling with youthful Port Charlotte (see: Extending the Life of your Whisky). In the end, we found a better candidate in a 3 year old Glenallachie. Unpeated, bourbon cask starter, we thought that time spent in an ex-PX cask might provide just the finish that this malt was looking for.

Now, we must reiterate that we bought the Glenallachie after 3 years of maturation, all duties paid – this is, for all intents and purposes, a finished whisky purchase. We just decided that instead of drinking our gallons of whisky straight away, we’d like to store them in our own seasoned casks and see what happens. These will not be forming any part of a commercial release, they’ll be for our personal edification – but we’ll keep an eye on what’s happening to the 3yo spirit in the cask and let you know every so often the kind of effects a small PX cask can have on a 3yo single malt Scotch from a bourbon cask.

So, what did we learn in the first month (Apart from the fact that even an empty one of these is HEAVY)?



Experiment in Maturation
Filling a cask with 3 year old Glenallachie

Fresh (3yo Glenallachie)

The Glenallachie 3 year-old we started with was technically a fully matured single malt whisky, but it had not yet taken any steps to conceal its youth. In colour it was like straw blanched in strong sunlight, and in flavour it was not particularly subtle. But the variety that was revealed in our tasting notes suggests that this whisky was not short on personality, either.

I passed a sample of this fresh spirit around our Edinburgh office, allowing everyone who interacted with it just one item to describe their first impression.
First reactions were mostly a quick recoil, upward-shooting eyebrows and greatly dilated pupils, followed by a ‘Woooo…hahaha!’ vocalisation. Since that’s not really a tasting note, I pressed a little harder for something specific.

Some typical and nontypical descriptors of young whisky followed – ‘Nail polish! Unripe tomatoes! Jif Lemon!’  From this, we can surmise that the Glenallachie is quite fruity, though with a certain cleansing harshness to it. ‘Jif Lemon’ is a beautiful concession to the fact that the fruitiness is tinged with something a little harder…

Others were a little more charitable – ‘Sauvignon blanc?’ ‘Greengages?’ ‘Tsipouro?’. Now, those are quite fruity products that one is supposed to consume and enjoy. If you’ve not encountered Tsipouro, it’s a fiery Greek version of brandy, usually distilled from winepress residues and unmatured. Potent.

‘Maltesers’ ‘Pear Drops.’ got a mention as well. Well now, pear drops are an absolutely classic note, and Maltesers have a lovely sweet maltiness to them. Promising, I think – our young Glenallachie already has an idea of where it came from and what it wants to be. Let’s give it a little time.


After 2 weeks

Experiment in Maturation
Our whisky has taken on notes of cherries soaked in liquor.

After just two weeks in the quarter cask, there have been some considerable changes. An excellent reminder that a smaller cask achieves quicker maturation speeds.
The first thing that stands out is that the colour has changed. From looking a little sunbleached, our liquid has now spent a little too much time outside wearing low-factor suncream. It has a radiant pink-reddish glow to it, absorbed from the vanguard of PX sherry that had been waiting for it, soaked into the wood of our quarter cask.

The PX has also had a fantastic effect on the flavours in the whisky. As the sample circulated around the office again, entirely new words were chosen to describe its aroma.

‘Cloves’ ‘Honey’ ‘Sultanas’ ‘Honeydew melon’ and ‘Green malt’  were all mentioned in this second round – the whisky has noticeably sweetened, even in the short two weeks’ exposure to PX-soaked oak staves. It seems that the vestiges of fresh-fruity flavours survive in the description of sweet melon, while other more sugary notes have come to the fore.

Surprisingly, we even reached an alignment on two of the notes – two of our sensitive nosers named ‘Booze soaked Cherries’ and ‘Melting demerara sugar’ independently of each other, suggesting that these two notes had established themselves quite deeply within the Glenallachie’s profile. Very good notes, too – these are some very indulgent and desserty flavours, especially in such a youthful whisky. Things seem to be progressing well.


Experiment in Maturation
Likely from the oak wood, a definite note of cloves has taken up residence in the heart of the whisky.

After 4 weeks

One month into its new life, and the Glenallachie seems to have taken very well to its smaller accommodation in the 50l ex-PX quarter cask. The colour has darkened a little more – the tan looks  healthier this time. Another pass around the office, then.

‘Vanilla’ ‘Banoffee pie’ ‘Apple Strudel’ – it seems that the whisky has mellowed and calmed a bit. Desserty, dairy flavours like these are harder to call to mind if the whisky is still trying to blow your head off.

‘Cherries in Dark Sugar Syrup’ ‘Burnt Caramel’ ‘Cola’ – but those sherry notes of sweet darkness are very much a part of the profile now. ‘Cloves’ got another mention, too. Very pleasant, hopefully they will not become too dominant over time. Clove eugenol can be powerful.  And then things take a turn for the decidedly odd:

‘Pencil shavings’ ‘Dusty paper’ ‘Old Chippy Paper’ ‘Brown Sauce’ – Hmm. We seem to have some combination of woody and slightly vinegary. I hope that this will turn out to have been an false positive – the woodiness is great, but a note of vinegar may be a warning that not all is well with the cask. This is something we’re going to have to keep a very close eye on, and hope that it’s an illusion brought on by the youthfulness of this strongly alcoholic whisky.

Overall, though, I think this young whisky has taken to its new cask well. Sweet and nostalgic flavours are accumulating, and the final product looks set to be delightfully rich and comforting.
I have to stress, however, that the Glenallachie has not completely transitioned to a point where you could ever mistake it for a long-aged, carefully matured sherry-bomb whisky. It may be darker, it may offer more reminiscences of sticky desserts and mulled drinks; but those flavours haven’t quite settled yet. The original sharp fruitiness leads, and the sweeter flavours arrive suddenly a bit later. The flavours don’t feel well integrated yet, and there’s a youthful brashness to it all that could probably be worked on some more.

quarter cask
From the almost colourless 3yo Glenallachie, the 2 week and 4 week PX cask samples are adding colour and getting darker with time.

The Origins of Flavour

Much ink has been spilled, and many pixels burned out in service of writing about where the flavour in whisky comes from. If you already feel intimately familiar with why whisky tastes the way it does, and where it picks up all its flavours, then this section may be safely jumped over… at the risk of missing a wee whisky factoid!

Green Malt/Maltesers
You can’t make a Scotch without fermenting the juice of malted barley, and so it’s no surprise that younger whiskies can still carry some of those wonderful malty, roasty notes in their early stages.

Pear Drops/Honeydew/Nail Polish/Jif Lemon!
Esters; light and aromatic molecules which help to make fresh fruit and flowers broadcast their appeal and can be formed almost anywhere during whisky production. They’re often associated with fermentations that are long enough to get lactobacilli working alongside yeast – producing aromas that are reminiscent of fresh fruit in low concentrations, and paint strippers if there’s a high concentration (pear drops embrace this duality enthusiastically). Oak maturation can also encourage more esters to form, so these smells are often found in simple white-oak matured whiskies like our starting point of 3yo Glenallachie. They may be harsh while the whisky is young, but they’ll soften over time.

Sultanas/Cherries/Honey/Demerara Sugar
The Pedro Ximénez Sherry that lingered within the wood of our quarter casks was the result of a dark, sweet and fortified white grape wine. It should come as no surprise that a whisky that has been allowed to interact with PX-sodden wood will take the flavours of raisins, red or dried fruits and sweet sugary syrups right to heart. Our Glenallachie did so most readily, though it does feel like it hasn’t quite figured out how best to arrange these exciting new flavours yet.

The wood of any tree is a complex biological substrate, but nature has a limited set of tools for building. The woody dried flowers of the clove tree are very rich in clove oils, but the eugenols that grant that characteristic flavour are also present in oak wood. Our quarter casks seem to have also been quite high in eugenol, but with time it would be no surprise to detect whiffs of cinnamaldehyde acid or vanillin (or other spicy aromatics) coming to join the party. A hint of vanillin was also coming in by week 4.

Woody/Papery/Pencil Shavings/Vinegary

Experiment in Maturation
These casks will guard their contents, and slowly change the whisky within.

The whisky is stored in an oak cask – it’s going to taste of wood. Fortunately, those oaky notes are a great part of the appeal of all kinds of matured spirits and wines. The vinegary notes, however, may possibly be a sign that a bit of wooden stave isn’t entirely healthy. Oak wood is pretty sturdy, but if a little rot sets in, that’s not great for the whisky – it can bring out some vinegary flavours. My hope is that this sharpness was an illusion brought on by the strength of the spirit – but if this cask isn’t at its best, we still have another 5 octaves of ex-PX Glenallachie that can carry the torch!


Future Plans

For now, we are simply content to see where this experiment goes. It was quite some work to get the casks into our office and to construct a suitable wooden rack to make sure they were safely kept in place. Each cask had to spend a few days filled with water to ensure that the dry staves became plump and watertight before we filled the cask with the Glenallachie Malt. It’s not a proceedure I’d recommend you attempt at home unless you have a good, clear space to work on casks and make sure they’re ready for the task ahead. That said, it is very satisfying to see a plan come together.

Now that we’ve got our collection of six filled and maturing quarter casks, we’re going to keep track of how they’re developing and share our thoughts. Future editions of the Cask 88 newsletter may include progress updates and tasting notes. Quarter cask maturation is fast, so a year may be enough to change our whisky entirely. Watch this space, and pray that the angels are kind!

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