Why does my whisky taste of sherry?

A potted history of the whisky industry’s long-standing love affair with sherry.

Of the myriad factors which influence Scotch whisky during its production none is more important than the time it spends ‘in wood’, to use an industry phrase. And little wonder: new make spirit can be produced in a matter of days whereas maturation takes, at the very least, three years – and very often much more than this. What’s more, it’s estimated that up to 70% of the character of the whisky we drink develops during maturation. But why did we begin using wooden casks in the production of whisky? To answer this we must pay a visit – and due homage – to Spain.

Britain once had a great and long-standing love affair with the Spaniards’ national drink. Since the Elizabethan times sherry had been a major import and by the late 1800s some 60,000 casks were making the journey annually. It was a welcome scenario for whisky distillers who were willing to use anything and everything to store their newly made spirit. To those who left their spirit in the ex-sherry casks for any length of time, though, it was positively game changing.

Imagine filling an ex-sherry cask, its individual staves saturated with deliciously sweet wine, and forgetting about it, only to discover it later, not full of harsh, fiery spirit but spirit which is darkened, matured and distinctively mellowed. The cask might have previously contained a Pedro Ximénez, giving the whisky a distinctly plummy sweetness, or it might have contained an Oloroso, in which case the whisky may well be dry and nutty with rich toffee notes. Whatever the case, it is presumed that this was the birth of matured Scotch as we know it, and it wasn’t long until the practice rapidly spread and the resultant taste became the norm.

Hard times for sherry

It also wasn’t long, though, before Britain’s love of sherry fell into sharp decline – ill news indeed for whisky distillers who, by the turn of the century, were filling butts faster than the Brits were drinking sherry. All was not lost though: the bourbon industry in America was now taking off. By law, bourbon must be matured in new oak casks, and as these casks cannot be reused by bourbon producers they quickly became the mainstay of whisky maturation in Scotland.

Today, sherry casks make up around 5% of some 20 million plus casks containing maturing Scotch whisky. The majority of these are modelled on the ‘transport’ cask, i.e. the casks which traditionally contained export sherry. Changes in export law meant these casks were no longer used after 1981 and so producers turned to Spanish casks made especially for the whisky industry. Constructed from either European or American oak, these casks are filled with sherry only for up to three years, emptied, and then sent to the whisky distilleries of Scotland where they are reused once, twice, even three times over as ‘seasoned’ sherry casks.

Sherry casks taken from the solera system, the cornerstone of the sherry industry, are used in whisky maturation too but they are far from common. Also known as ‘aged’ sherry casks, by the time they have spent anywhere up to five decades in bodegas they are often held together with nothing more than sediment and require skilled coopers to restore. Needless to say, they are much more expensive than, say, bourbon casks, and tend to be favoured largely for finishing whisky. Interestingly, while they are able to impart huge, desirable sherry characteristics to whisky, they don’t give up much in the way of wood; this is the job of the seasoned sherry cask.

For finishing or maturing, for flavour or aroma, the use of sherry casks in the whisky industry today, then, is an art of balance, and a fine one at that. To some, sherried whiskies represent matured Scotch in its most natural and authentic form because of their heritage. But with a booming whisky industry and a comparatively stagnant sherry one, the future of sherried whisky is far from certain. There is, however, a potential – and mightily potable ­- solution: whisky fans must simply drink more sherry.


Sherry cask specifications

Once reconstructed, sherry butts have a capacity of 500l. The gorda, or the bodega butt, has a capacity of 600l, while the sherry puncheon holds 450l.

Sherry-forward brands

Glenfarclas
The Dalmore
The Macallan
Tamdhu

Typical flavours of sherried whisky

Prunes, raisins, dates, figs, almonds, walnuts, hazelnuts, fruitcake, toffee, fudge, (occasional) sulphur, herbs, Christmas pudding.

Sherry or not

By law, sherry must be produced in the ‘Sherry Triangle’ of Cádiz in southern Spain. Regardless, the whisky industry refers to casks which have held other such fortified wines as ‘sherry casks’, even if legally they’ve never contained sherry.