Recognising sherry cask character

Where sherry casks come from

Sherry is a fortified wine from the area around Jerez in southern Spain. For centuries it was shipped to Britain in oak casks. Scottish distillers reused those empty casks to mature whisky. The flavour of sherry soaked into the wood came out again in the spirit.

Sherry is no longer shipped to Britain in cask, so today most sherry casks for whisky are made to order. Coopers build the cask, then it is filled with sherry for a period, often a year or two, to season the wood before it is emptied and sent to a distillery. These seasoned casks are the main source of sherry character now. Our guide to ex-bourbon, sherry and wine casks covers the trade side.

The core sherry cask notes

The classic signature is dried fruit: raisin, sultana, fig, date and prune. Around it you often find:

• Nuts: walnut, almond, hazelnut.
• Sweet spice: clove, cinnamon, nutmeg.
• Dark sweetness: toffee, treacle, dark chocolate, coffee.
• Orange: marmalade, candied peel.

Put together, people often describe it as Christmas cake or fruit cake. In India, the comparison that lands for many tasters is plum cake at Christmas or the dried fruit in a rich mithai. Colour is a clue too. Heavily sherried whisky is often deep amber to mahogany, though caramel colouring means colour alone is never proof.

Oloroso, PX and fino taste different

Sherry is not one wine, so sherry casks are not one flavour.

• Oloroso is a dry, nutty, oxidatively aged sherry. Oloroso casks give walnut, dried fruit, leather and spice. This is the most common sherry cask in whisky.
• Pedro Ximénez (PX) is a very sweet, dark sherry from sun dried grapes. PX casks give sticky raisin, date, molasses and syrupy sweetness.
• Fino and manzanilla are pale, dry sherries aged under a layer of yeast called flor. Their casks give lighter notes: almond, salty, bready, sometimes a little savoury.

If the label names the sherry type, use it. A PX finish and a full oloroso maturation will taste very different, even from the same distillery.

European oak versus American oak

Many traditional sherry casks are made from European oak (Quercus robur), often from Spain. Others are made from American white oak (Quercus alba). The wood matters as much as the wine.

European oak is generally richer in tannins and gives drying, spicy, clove-like notes and a firmer grip on the palate. American oak gives more vanilla and coconut sweetness. A whisky from European oak sherry casks often feels drier and more tannic than one from American oak sherry casks, even when both held oloroso.

Size matters too. A sherry butt holds about 500 litres. A hogshead holds about 250. A larger cask has less wood contact per litre, so it works more slowly.

Full maturation versus finishing

A whisky can spend its whole life in a sherry cask, or spend most of its life in another cask and then a final period, often months to a couple of years, in sherry wood. The second approach is called finishing. Our guide to cask finishing in whisky explains the method.

On the nose, a fully sherry matured whisky usually has sherry character woven all the way through. A sherry finish often sits on top: dried fruit and sweetness up front, with the original ex-bourbon vanilla still clear underneath. Tasting the two side by side is the quickest way to learn the difference.

Sulphur: the fault that hides in sherry

Sherry casks have a long association with sulphur notes. The usual explanation is the old practice of burning sulphur candles inside casks to keep them clean in storage. Some sulphur notes also come from the spirit itself, depending on how the stills were run and how much copper contact the vapour had.

A faint struck match note can add depth. A strong note of rubber, burnt matches or boiled cabbage is a fault. Some tasters are much more sensitive to sulphur than others, so do not assume your friend smells what you smell. Our guide to sulphur and feints off notes goes further.

When the cask takes over

A first fill sherry cask can be powerful. In Indian heat, where whisky interacts with wood faster than in Scotland, a few years in an active sherry cask can push the spirit well into the background. The result can taste like sherry and oak with very little of the distillery left.

Some drinkers love that. If you want to understand the spirit, look for refill sherry casks or a blend of sherry and ex-bourbon casks. Training yourself to taste through the cask to the distillery character is one of the harder skills in whisky. It takes guided practice.

Taste a sherried and an unsherried malt

Your first step: pour 20 ml of an ex-bourbon matured single malt and 20 ml of a sherry matured malt into matching tulip glasses. Nose each neat, then with a few drops of water. Write down every note that appears only in the sherried glass. That list is sherry cask character in your own words. Sip slowly, drink water between pours and never drink and drive.

Common questions

What does sherry cask whisky taste like?

Typically dried fruit, raisin, fig, walnut, sweet spice, toffee and dark chocolate, often described as Christmas cake.

What is the difference between oloroso and PX casks?

Oloroso casks give drier, nutty and spicy notes. PX casks give very sweet, sticky raisin and date notes.

Why do some sherried whiskies smell of sulphur?

Partly from the old practice of burning sulphur in casks and partly from the spirit itself. A faint note is fine. A strong rubbery note is a fault.

Is a dark whisky always sherry matured?

No. Caramel colouring and other cask types can also darken whisky, so colour alone is not proof.