Scotch whisky is chosen to be aged in sherry casks primarily to give the whisky a unique taste and flavour profile. Sherry casks are barrels made from oak and after the sherry ageing process, the sherry residue left in the cask interacts with the whisky to give it the fruity, spicy and nutty flavours of sherry.
Sherry casks can offer a wide range of different taste and flavour profiles, depending on the type of sherry previously stored, the history of the cask and the time spent in it. Common types of sherry casks include Oloroso sherry and PX sherry, both of which bring different aromas and flavours to whisky.
As for the time spent in the cask, this is a relatively flexible issue as the ageing time depends on the whisky producer’s preferences and target palate. Scotch whisky usually needs to be aged in casks for at least three years before it can legally be called ‘Scotch’. However, many high-quality single malts choose to age in sherry casks for longer, often 8, 10 or even longer, to give more complexity and depth to the spirit.
In short, Scotch whisky is aged in sherry casks to give it a unique flavour and complexity. The ageing time can vary from producer to producer, but usually, a minimum of three years is required.