The interaction between spirit and cask is a complex system based on the extraction of molecules from the wood and their interaction with the distillate. Wood constituents migrate into the liquid, whilst other compounds both form and degrade over time. Levels of ethanol, wood lignins, volatile congeners, vanillins and oxygen to name but a few, all have their part to play in forming the final aroma and flavour profile of the resultant whisky. However, when you take all other things as being equal, the size of the cask and its relative surface area when compared to the distillate can also have a dramatic effect – the smaller the cask, the faster the exchange of compounds between spirit and wood.
An octave cask (from the Latin – octavus: eighth) is created from the staves of a previously used cask and comes in at roughly an eighth the size of a butt (around 65 litres). Its small size offers greater interactions levels, but likewise, can result in unusually balanced whiskies (compared to full-sized hogsheads, barrels and butts) due to inherent differences in the ratios of the concentrations of extractives and the relative oxidation rates produced in miniature casks. Various experiments have been conducted on the effect of smaller casks on whisky. Some, such as A.D Rattray’s Octave Project look to provide the imbiber with a vision of the differences that precursor liquids can make in smaller casks. Other’s such as this article from the Journal of the Institute of Brewing look to scientifically measure the effect of small cask maturation – be warned, this one is heavy reading!
During Billy Walkers tenure with Glenglassaugh he investigated the results of maturing the distillery’s spirit in octave casks. Initial releases were sold as private casks until 2016, when the distillery launched two new widely available expressions – Glenglassaugh Octaves Classic and Octaves Peated. Both were produced as NAS bottlings, clocking in at roughly 7 years of age (given the production timeline). 2018 saw the release of a second batch of both expressions – still NAsS but now, likely a little older at around 8/9 years of age.
Today we’ll take a gander at Glenglassaugh Octaves Peated Batch 2. This expression has been created by reusing staves from casks that previously held bourbon, port and oloroso sherry – as Adam Wells from Malt amusingly describes – Victor Frankenstave. It’s delivered at 44% ABV and can be purchased for just over £61 from Master of Malt.
Nose: Orchard fruits (pear and particularly apple) present first, with creamy fudge and icing sugar providing a sweet lift. Barley water and coconut provide some ex-bourbon reinforcement. Running throughout is chalky mineral smoke – not quite coal dust, but heading in that direction. The addition of water brings out some walnut nuttiness as well as highlighting ginger spicing.
Taste: The arrival is silky, and delivers an array of smoke-tinged flavours – burnt toffee apple, smoked sea salt, malts and oats. Caramel popcorn and vanilla pod sit with wet soils and moist oak. There’s a sense of coastal sharpness and chiselling with hewn granite and spent charcoal before more overt oak influence starts to take hold. Reduction ups the toffee flavours whilst adding in some ashy chalkiness – it does however reduce the definition elsewhere, so I’d stick to this at its delivered 44%.
Finish: Medium in length, sweet with caramel, burnt with cask char and with growing drying oakiness.
Glenglassaugh Octaves Peated Batch 2 delivers a relatively easy-going, gently smoked rather coastal-style whisky. It’s possibly a mile-marker whisky for someone on a smoky journey who’s not yet ready to subject their palate to more intense and bolder peated expressions. Whilst the octave has imparted an array of balanced flavours on the nose, the palate, particularly in the finish becomes somewhat acrid and drying with oak influence. It’s pleasant enough, but feels a touch overpriced for what’s on offer here.
With thanks to Loz for the sample