Sherry barrels have been adding their magic to whisky aging process for over 200 years, bringing a very different flavour profile when compared to whiskies aged solely in bourbon barrels. While bourbon barrels add sweet vanilla and coconut notes, sherry barrels sprinkle in a delightful mix of nuttiness, dried fruits, and spices, although different types of sherry do bring their own unique profiles to the party.
Sherry wines are born in a special place called the “Sherry Triangle,” located in the sunny south of Spain between Jerez de la Frontera, Sanlúcar de Barrameda, and El Puerto de Santa María. The wines from this region are like nothing you’ve ever tasted and are made using methods that might surprise even the most experienced wine lovers.
Sherry is a fortified wine that ages in oak barrels for at least 10 years using a unique process called the ‘Solera System.’ Barrels are grouped by age (called criaderas), and each year wine is taken from the oldest group to be bottled. It’s then topped up from the next youngest group, and so on. This means the barrels are never fully emptied, always containing a blend of wines of different ages and that every bottle is comprised of a blend of many different harvests. By law, only a third of the barrel’s contents can be removed, ensuring a fascinating mix of flavours in every sip. 
Our distillery manager Jacob is recently back from a brief spell working in Portugal. Before he returned home to Uist we sent him on a detour to the sunny south of Spain to visit a variety of the country’s oldest sherry bodegas, looking for the perfect casks in which to age our upcoming Nunton whisky. We’ll soon talk a little more about his trip and what goes into finding the perfect partnership of sherry bodega and whisky distillery, but first, a small introduction into the fascinating world of the delicious fortified wine that is going to play such an important role in creating North Uist Distillery’s unique whisky profile.
Sherry wines come in two main types: those aged biologically like Fino (from Jerez) or Manzanilla (from Sanlúcar), and those aged oxidatively like Oloroso and the sweet Pedro Ximénez (PX).
Biologically aged sherry, like Fino and Manzanilla, starts as a fresh wine fortified to 15% ABV. It's then aged under a layer of wild yeasts and microbes called Flor, which protects the wine from oxygen and breaks down glycerol, giving the wine a dry, delicate profile with herbal and mineral notes.
Oloroso, on the other hand, is a dry wine aged oxidatively. It's fortified to a higher alcohol content, preventing the Flor from forming and allowing oxygen to interact with the wine. This style, while dry, has a perceived sweetness due to the presence of glycerol. Oloroso wines are dark and rich, with flavours of toffee, walnuts, and figs.
Pedro Ximénez (PX) is a sweet treat made differently. The grapes are sun-dried to concentrate their sugar before pressing, resulting in a wine with extremely high residual sugar (300-400g/L).
Some sherry styles, like Amontillado and Palo Cortado, combine both biological and oxidative aging, offering complex flavors from both processes.
In the world of whisky, Oloroso and Pedro Ximénez are the stars. Oloroso casks infuse whisky with dried fruits, figs, and nuts, while PX casks add sweetness to these flavors. Amontillado casks bring an extra layer of complexity with their unique aging process.
So, next time you savour a sip of sherry-aged whisky, remember you're tasting centuries of tradition and a whole lot of carefully managed aging. Whether you're into the nutty notes of Oloroso, the sweet treat of PX, or the balanced complexity of Amontillado, sherry casks bring something special to single malt whisky aging and we are beyond excited to be bringing that complexity to our Nunton made whisky.
Join us again soon to hear more about Jacob’s journey to some of the oldest sherry bodegas in Spain, looking for the perfect barrels to bring home to Uist and integrate into the Nunton whisky journey from bere barley to uisge beatha.