So what is peat, and why is it so awesome?
In simple terms, peat is basically thousands of years worth of build-up of dead or dying plant life. In a wetland-type environment, the water saturation on the surface slows the decay of decomposing plant matter, causing it to accumulate and over time form peat bogs. In fact, the majority of the wetland areas in the world are peat bogs.
More importantly for us though, dried peat can be used as a fuel, and was a major source of fuel in many areas of the world, before being replaced by coal. This means peat was used for fires, and those fires were used to dry the malted barley that was to become whisky. When dried peat is burned, the smoke gives off a uniquely smoky, vegetal aroma, which permeates the malted barley, and these aromas and flavours are present in the finished whisky. Peated perfection!
So, peat is so awesome because it gives our whisky the smoky, earthy, vegetal flavours many people love. Some don't, but in my opinion they are missing out. While these flavours can be surprising if they're not expected, particularly if one's Scotch whisky experience is limited to Johnnie Walker & coke (for example), the amazing depth they add to a whisky should be reason enough to try one. Most people prefer their spirits to be sweet, but if you add some peat smoke to balance out that sweetness, the effect is truly awesome.
There are many different levels of 'peatiness' used in whisky production, which is usually governed by how long the malted barley is dried using peat smoke, and/or the portion of the malted barley used that is dried using peat smoke. For example, Springbank distillery in Campbelltown, Scotland, produces three different whiskies: the standard Springbank, which is lightly peated, Longrow, which is heavily peated, and Hazelburn, which is un-peated. For the Springbank whisky, the malted barley is partly dried using peat smoke for a relatively short amount of time, for the Longrow whisky, all the malted barley used is dried using peat smoke, and it is smoked for a longer amount of time, and for the Hazelburn whisky, no peated barley is used at all.
The level of 'peatiness' can sometimes be researched by looking for a 'ppm' level, which is the phenolic content (peat smoke is a phenolic compound) measured in parts per million in the malted barley. Some distilleries utilise these measurements as a marketing tool as well, Bruichladdich distillery for example is not shy with telling you their 'Port Charlotte' range is peated to 40 ppm, and their 'Octomore' range is much higher, up to 258 ppm. To my knowledge, this is the highest in the world. However, this ppm measurement is not always a good indicator of the finished product, as it is measured before the brewing, distilling and ageing process takes place. The finished product is also heavily influenced by the shape and size of the stills and condensers, and the peaty flavours also diminish over time during maturation. This is why many heavily peated whiskies are bottled and sold at a relatively young age, for example the Bruichladdich Octomore range is aged for only 5 years, retaining its maximum peatiness. As a general rule of thumb, a peated whisky will lose around 60% of it's phenolic compounds before it is bottled. So, if you're looking for a heavily peated whisky, do not take the age statement as the main factor in your purchasing decision, in fact be wary of an older (18 years or older) whisky claiming to be heavily peated, as you may not get what you wished for. Enjoy!