This 25 year old expression completes The Balvenie Single Barrel range.

As with the other expressions in the range, each barrel is unique and is personally selected by The Balvenie Malt Master, David Stewart, to ensure that the individual characteristics imparted by that barrel also reflect the classic Balvenie style of rich, honeyed sweetness and subtle spice.

The whisky remains non-chill-filtered and each barrel produces no more than 300 hand-numbered bottles, with the label stating the distillation date, bottling date and cask number.

This has been drawn from a single cask, described on my sample bottle as ‘single barrel traditional oak’, which I guess means a refill American Standard Barrel, (ex-bourbon, with a capacity of aproximately 200 litres).

Pale gold, thick legs. Malty porridge, bruised pears and candlewax on the nose, which is also lightly prickly to start with – surprising for this strength. The taste starts very sweet and dries elegantly, with fragrant peppery spice lingering in the aftertaste. Water softens the texture, and reduces both sweetness and spice

Scientific understanding of the chemistry of oak wood and of what is happening during maturation is relatively new, simply because before the 1970s the scientific techniques for exploring such matters were unavailable. Chemists now talk about ‘cask activity’, and believe the wood performs three crucial functions, described as ‘subtractive’ ‘additive’, and ‘interactive’.

Subtractive effects

In order to be bent into a barrel-shape, the staves must be heated, and heat performs the vital function of altering the chemical structure of the inside surface of the cask. European casks are ‘toasted’ to bend them into shape; American casks are flamed once they have been made, so their inside walls are charred as well. The benefits of charring were probably discovered accidentally: carbon acts as a ‘purifier’, removing ‘immature’ characteristics and extracting undesirable compounds from the new spirit. Since European casks do not have a heavily charred interior, their subtractive activity is not as pronounced as American casks.

Additive effects

Oak contains hemicellulose (which caramelises when heated, adding sweetness and colour), lignin (which, like hemicellulose, degrades when heated to produce vanillin and coconut flavours) and tannins (which produce astringency, fragrance, delicacy and colour). As might be imagined, a brand-new cask is much more active than one which has been filled before, so almost all Scotch whisky casks are ‘seasoned’: they have been used previously for maturing bourbon (mainly) or other spirits, sherry or other wines. The first time they are filled, there may be residues of the previous incumbent – Bourbon, sherry, etc. – lurking in the walls of the cask, but the most obvious additive effect is colour. European oak, being more tannic, lends its contents a deeper hue than American wood. The degree of colour depends upon how often the cask has been filled, but as a general guide, European oak hue runs from ‘old polished oak’ to ‘young mahogany’, while American oak hue is all gold: 18CT through to 9CT (deep amber to pale straw).

Interactive effects

Oakwood is semi-porous, which allows the contents of an oak cask to ‘breathe’ and interact with the air outside. This leads to oxidation, which removes harshness, increases fruitiness and enhances complexity. The spirit is said to ‘breathe’ through the wood, and over the years it generally loses both volume and strength. The interaction between the wood and the atmosphere is the least understood of the mechanisms of maturation, and some say the most important. It is also the mechanism most affected by the micro-climate of the warehouse in which the cask rests during maturation. Heat, humidity and atmospheric pressure all play a part. This expression of The Balvenie has been filled into relatively inactive refill casks, the first (c.4567) into European oak, the other two into American oak. Their idiosyncratic flavours owe a great deal to the interaction between the spirit and the atmosphere of warehouse 24: unique flavours which can only be developed by time.