PEATED WHISKIES

THE INFLUENCE OF PEAT ON WHISKY

A true whisky fan would have heard the term ‘Peat’ somewhere. To whisky connoisseurs, the word ‘peat’ or ‘peaty’ to describe a whisky has a specific meaning. The general public, however, associates that term with ‘smoky’, which is incorrect.

While peat has a definite flavour, it also delivers the smoky flavour found in many whiskies. How peat is used in that whisky’s production determines just how peaty and smoky the whisky will turn out. Once tasted, peat is never forgotten. Islay malts aren’t exactly known for their subtle flavours, and it is its highly localised peat that has made the island’s whiskies so popular in the world today.

But What Exactly is Peat?

Peat is a mixture of partially decaying vegetation and organic matter that accumulates in natural, water-saturated environments known as peatlands, bogs and mires. The layers of peat found in the peatlands of Scotland have been forming for thousands of years and in that time have grown up to 5 meters thick. While some bogs may have been forming for 50,000 years, most are between 5,000 and 10,000 years old. Peat is so tightly compact and dense that it burns for a long time and with consistent heat and acrid smoke. This is also why it is still used as a domestic fuel in some areas of Scotland, especially the Islands.

In Scotland and Ireland, as well as many other countries with similar geographical and topographical features, peat has been used throughout time as a source of fuel, similar to coal. The peat is accumulated, cut into slices with special tools and stacked in piles to enable the contained water to dry out over three to five weeks. The peat then turns into hard bricks, ready for burning, and is used by farmers, energy companies and distilleries throughout the country. Even so, minor variations in topography can change the sensory features of peat found there. For example, Orkney Island peat is quite different to Speyside peat or Swedish peat or Islay peat for that matter. Of the lot, it is the true Islay peat that is inferred whenever the term peat is used.

Peat is found all over the British Isles and it is the use of peat in the Scottish whisky industry that helps to produce a drink that has a unique flavour.

Use in the Whisky Industry: Historically peat has been used in the whisky industry, especially as in many places it was the only consistent source of fuel. This process is time consuming and the use of peat dwindled as other fuels, such as coal and electricity, became more widely available. Now it is largely confined to the islands of Scotland - naturally they now have other fuel sources but many of the whiskies remain well known for their smoky, peaty flavours. Therefore, the distilleries have chosen to keep the practice so as to keep the distinctive flavours in their whiskies.

Peat is cut manually, using specialised tools and the resulting 'sod' is then left to dry in the open air. After this time, the peat is collected and then taken to the distillery. Most of the time the peat used is local to the distillery or cut from property owned by the distillery. The peat is burnt underneath the malted barley to stop its germination. Peat is so tightly compacted and dense that it burns for a long time and with consistent heat and acrid smoke. This is also why it is still used as a domestic fuel in some areas of Scotland, especially the islands.

Different characteristics

Peat: Peat is one reason why different distilleries have different characteristics in their whiskies. Peat smoke produces contains chemicals called phenols and these phenols are absorbed by the malted barley during the drying process in a kiln. The level of phenols are controlled by the length of time that the barley is exposed to the smoke, the amount of smoke produced and the type of peat used. The smoke that has been absorbed is then carried through the entire whisky making process and right into your glass.

Phenols: Once finished, the malt is taken away for mashing and the phenol level is measured. This level is known as the PPM – Phenol Parts per Million. A distillery will always have the same PPM for their malt and this value is also measured in the final spirit. Some is lost during distillation so the PPM is always lower at the end, roughly one third of the level of the original PPM in the malt. The PPM figure most commonly used is that of the malt. Most whisky has some smokiness but in most the PPM value is so low (1–3 PPM) that it is virtually undetectable. In smokier whiskies, it is easier to detect these levels as the PPM levels increase. 

Here are some examples of PPM values of some well known distilleries. The approximate PPM of their malt is in brackets in ascending order. 

    Bunnahabhain (1–2)
    Bruichladdich (3–4)
    Springbank (7–8)
    Benromach (8)
    Ardmore (10–15)
    Highland Park (20)
    Bowmore (20–25)
    Talisker (25–30)
    Caol Ila (30–35)
    Ledaig (35)
    Lagavulin (35–40)
    Port Charlotte (40)
    Laphroaig (40–43)
    Ardbeg (55)
    Longrow (55) 
    Ardbeg Supernova (100)
    Octomore 5.1 Edition (169)
    Octomore 6.3 Edition (258)
    Octomore 8.3.Edition (309)
    Octomore 15.3 Edition (307.9)

The make up of peat is different in different parts of Scotland and thereby influences the flavour of the whisky differently. There are very few trees on the Orkney islands so there are no tree roots in the peat making it lighter and quicker to burn. Whiskies from this area, like Highland Park, tend to have a lighter smoky flavour than Islay malts. 

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