Production and its influence on taste
Whisky production can broadly be seperated into four steps: Malting the grain, mashing it, fermenting it and then distilling it. There are several factors that influence the final taste of the whisky. It all starts with the type of grain/malt chosen and how it is malted. Malted over a peat oven or fire it is a peated whisky that has smoky flavours. The second significant, but very small influence is the type of yeast used for fermentation, with the duration of the fermentation having a slightly bigger influence. A larger part oft he taste comes from the shape of still used during distillation and the number of distillations. Scotch Whisky is typically double distilled, Irish Whiskey often Triple Distilled, but there are also Scotch whiskies distilled three or even “two and a half“ times.
Maturing and finishing
The generally accepted opinion however is that the cask maturation makes up about 75% of the influence on taste. Most whisky (and all Scotch) is matured in casks made from oak. The predominant oak types used for casks are American Oak (soft vanilla and caramel flavours) and European Oak (stronger spicier notes). Most casks used around the world are either Virgin Oak casks that didn’t hold anything before or, especially in Scotland, ex bourbon casks that held bourbon once. Today, a plethora of other wine and spirit types that were in the cask before it was used for whisky maturing to give the whisky an influence of the taste it held before. First Fill Casks did not hold scotch whisky before, Second Fill Casks once and so on. A refill cask has held whisky at least once (not counting Bourbon).
Most of the times a whisky is matured in one cask type, but people are getting more and more crazy with time. Today, reracking a whisky in another type of cask than the one it matured in has grown popular. This is called finishing.
A funny side note about finishes:
On a Scotland trip very early into our journey through the water of life we were attending a Cadenheads Warehouse tasting and Ege (The E in VAME) for the first time in his life came in contact with cask finishes. He bluntly told the warehouse guide that finishing a cask because you didn’t like it before is cheating. It did not sit well with the guide, but the tasting group was more than entertained. Was he wrong? Probably not, but we are doing the same thing. We love cheating!!!