Sherry casks play a huge role in the scotch whisky industry. And what’s not to love, with those delicious notes of sweet, dried fruits, nuts and baking spices, it’s basically a fruit cake in whisky form!
Sherry casks are deeply embedded in Scotland’s whisky-making tradition. Nowhere more so than in Speyside, the country’s most densely populated whisky region. While regional style distinctions have blurred in recent years, with distilleries increasingly experimenting across the flavour spectrum, Speyside remains strongly associated with sherried expressions. The region’s output continues to lean heavily on the rich, fruity influence of sherry cask maturation.
Securing a sherry cask
It used to be easier and cheaper to source sherry casks back in the day. Spanish wine cellars, bodegas, used to send boats full of sherry butts to Britain where the fortified wine would be bottled and sold. Rather than send empty casks back to Spain, the Scottish distilleries began filling them up with their own new make.
Following regulatory changes in the 1980s requiring sherry to be bottled in Spain, the supply of casks declined sharply, driving up prices. It takes a long time to age sherry. Even if the whisky industry has plenty of patience (waiting for their own whiskies to mature), they’d rather not wait for the sherry to come of age as well. Instead, they commission bodegas to season casks for them.
The casks are custom built in Jerez to match the distillery’s requirements and then filled with sherry wine and left to macerate until there is enough influence left in the wood. This process takes only around 12 to 18 months, sometimes up to 24 months. Distilleries like Macallan and Glendronach are known to pay for extended seasoning to allow more consistency in their casks.
It is estimated that around 10% of casks used in the scotch whisky industry are a type of sherry, which actually surprised me. Somehow, I expected the number to be higher, considering the popularity of sherried releases. The majority of casks are ex-bourbon (90%), leaving 1–2% for alternative cask options.
So, what is sherry exactly?
Sherry is a Spanish fortified wine made only from white grapes, and for it to be allowed to be called sherry, the grapes and the production should take place in the sherry triangle in the Andalucía region of southern Spain.
Blending is the most important part of the whole production and should always be done the same way to keep the quality consistent. Different ageing levels are blended together in a unique way, known as solera. The barrels are arranged in groups on top of each other, in tiers. Each tier contains wine of the same age.
They take a small amount from the bottom cask to be bottled – this is the oldest liquid. Then the same amount is replaced with wine from the next oldest barrel, and that one is then replaced from the next layer, and so on until the youngest one. The youngest layer contains the new wine.
The sherry industry avoids using new oak, and most of the casks used in solera are at least ten years old. These casks have been seasoned with wine before being used for sherry. The different varieties of sherry get their unique flavour through a range of ageing methods.
For example, oloroso has contact with air, which contributes to its fruity and nutty flavours, while fino is protected from the air by a layer of yeast, also known as flor, and this keeps the sherry light and crisp. Pedro Ximénez (PX) gets its sweetness from raisins; the grapes are left to dry in the sun before being fermented.
There are three main groups of sherry: dry, naturally sweet and sweet. Within these categories you will find more specific sherry styles. See my previous blog post Sherry Styles Explained for more information.
How does sherry influence whisky?
After the seasoning is done and the cask emptied, there may still be up to ten litres of sherry left inside. It simply soaks into the wood, which will have a huge impact on the flavour and colour of the whisky. The inside of the cask is usually kept slightly wet while it is being transported from Spain to Scotland.
Other contributing factors are the number of fills and the type of oak used. The more fills, the more reduced the sherry influence will be. Most of these casks are American oak rather than European oak. American oak gives a softer, sweeter taste with notes of vanilla and caramel, while European oak is spicier and has a stronger wood input.
Oloroso is the most common sherry style in whisky maturation, and usually when the label simply mentions ‘sherry’ it means oloroso. Any other type of sherry cask and they tend to showcase the details on the label. Oloroso casks can be used for full maturation or for secondary maturations, while other sherry styles are commonly used for finish only.
This is due to the cost and availability of these casks but also to the intensity of flavours coming from certain sherry styles. Casks like fino could make the whisky overly dry or bitter if it is left in for too long. The finishing period allows the blender to balance the nuanced flavours to complement their own distillery character.
Oloroso brings dried fruit notes (anything from sultanas to dried cranberries), alongside leathery undertones and roasted nuts. It can also be slightly drying. PX is sweeter, more syrupy, so it tends to impart richer notes such as dates, raisins, figs, even toasted coffee beans or molasses. Amontillado is very nutty so the spirit will take a lot of those drier nutty notes together with some winter spices and oakiness.
Due to its unique ageing process, Palo Cortado brings slightly different flavours to the table. It offers more savoury notes and saltiness, together with citrus (usually orange) and oilier nuts such as hazelnuts. As both fino and manzanilla are light and crisp, the impact on the whisky is completely different. These will bring dryness, freshness and a salinity. Fino leaning more towards herbal elements. When Manzanilla is usually a bit fruitier so it can add subtle citrus fruit and floral notes as well.
Try these sherry cask matured whiskies:
Tomatin 18-Year-Old Oloroso 46% ABV
The secondary maturation in first-fill oloroso butts have given this whisky a rich and luxurious flavour profile. Aromas of dried fruits, winter spices, and a touch of nougat. The palate is honeyed and slightly tropical. Plus notes of dark chocolate, soft spic, and fruit cake.
GlenAllachie 15-Year-Old 46% ABV
The combination of PX and oloroso casks have created a rich whisky with aromas of dark cherries, figs and dates. On the palate you will get warming winter spices, dark chocolate, candied ginger, coffee, and nuts. Ideal whisky for the festive season.
In fact, GlenAllachie is celebrating the Sherry Week (3-9th November) with three new 9-Year-Old single cask releases; Fino, Amontillado and Oloroso.
WhiskyHeroes Glendullan 15-Year-Old Amontillado 55.1% ABV
The Gathering of the Seven Hills release was finished in a first-fill amontillado sherry hogshead, adding rich and nutty flavours. You can also expect red berries, stewed fruits, and earthy notes. It’s not that often you see bottles of Glendullan single malt.
In general, WhiskyHeroes range consist of several sherried releases so something to keep an eye out. One of my favourites was a Blair Athol in Palo Cortado. See my previous blog post for more about the brand.
The nose offers aromas of apricot, nuts, coconut with an outdoorsy/mushroomy edge. The sweet smoke is delayed and gentle. The palate is slightly oily with notes of orange, dried cumin, ginger, and almonds. A great release from the young distillery.
Old Perth Manzanilla 53.4% ABV
This limited-edition blended malt whisky is a combination of 11 manzanilla casks (six hogsheads and five butts). On the nose you will find floral aromas, yellow plum, almonds, and hazelnuts. The palate displays marzipan, candied almonds, and crips apples.
Kilchoman Fino Sherry Matured 50% ABV
This whisky was aged for a minimum of five years in 20 Fino sherry casks. The dry, ashy peat is complimented with vegetal notes, herbs, citrus and walnuts. The palate is surprisingly sweet with notes candied citrus peel and caramel. Crips apple and more herbs in there too. A delicious example of fino influence.
Do you like sherry matured scotch whisky? What is your favourite sherry style or a favourite sherried whisky?
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