|This is Peat. Say "Hi, Peat."|
For those that love it, there are a few categories that one may fall into. Some love the sherried-sweetness of Speysides. Others may love the brinier island styles (Orkney, Arran, Skye etc.). Then there are the "Peat Heads" - the lovers of Islay (excluding Bunnahabhain).
Lagavulin is the "nectar of the gods" to some. Others swear by Laphroaig's juice of the barley. Whether it be from Ardbeg or Bruichladdich, Islays are known for their heavily-peated whiskies. I've had at least one release from all of the above: all fine scotches.
But what makes a scotch "peaty"?
Personally, my favorite Islay malt is Caol Ila. It has a very iodine-rich flavor, but somewhat lacking in smoke. I was surprised, however, to hear that it's not as heavily peated as the others mentioned above: I associate that iodine flavor with peat. Furthermore I was speaking with a customer recently about his favorite Islays and he claimed Caol Ila was the worst because it wasn't peaty enough for him, same with Ardbeg and Bruichladdich, but Lagavulin's 12YR "Cask Strength" was his favorite (more so than the "normal" Lagavulin 16YR) because it was "smokier." I got a little lost in his use of "peaty" and "smokey." I couldn't tell if it was just semantics or if he meant different flavors. This got me thinking about how "Islays" are classfied as the peatiest of the single-malts and what "peaty" meant.
Before I go any further, I have to warn you that things are about to get kind of nerdy. There will be some chemistry. However, as a nerd, I also feel it is my duty to say my education of chemistry is limited to whatever was taught to me at the NYS Regents level back in 1997-98. While I try to be as diligent as I can in finding the correct information online (mostly through Wikipedia), I admit I am not adequately educated in chemistry to fully understand or explain the molecules and their properties mentioned below.
Yet, this is what makes alcohol so interesting to a nerd like me: there is always something to learn and to share with you.
Back to peat.
My initial online research brought me to this PDF I found from The Whisky News: it's very informative. It begins with an explanation of what peat is (i.e. wet, rotting vegetative matter) and its historical connection to the scotch whisky industry. The most interesting part (to me) is the penultimate section entitled "Phenols and ppm." Phenols are, in a sense, aromatic molecules. In the scotch whisky industry, the amount of phenols are measured in PPM (Parts Per Million). So when Bruichladdich's Octomore claims to have 167 ppm of phenols, one can assume that this is a heavily-peated whisky. However, as this Whisky News article points out, that is the concentration before milling and mashing and these may cut that ppm in half in the final distillate. Furthermore, aging actually decreases phenol concentrations over time, too. This makes some sense why that customer mentioned above preferred Lagavulin's 12YR to their 16YR. Yet phenols are a large group of aromatic molecules, each molecule having different aromatic qualities.
More research required.
If the research methods classes I had as an undergrad and graduate student taught me anything, it was to check the citations - so I did. This article from Vol 107, No. 5, 2001 in The Journal of the Institute of Brewing & Distilling entitled "Origins of Flavour in Whiskies and a Revised Flavour Wheel: a Review" (pp 287-313) does a good job of classifying the peated characteristics into "[q]uantitatively important" phenols: phenol, cresols, guaiacol (295). Each represents a different attribute of "peatiness." Phenol, normally extracted from coal tar, imparts that almost "asphalt-like" flavor. Cresol is similar to phenol. Guaiacol is smoky too, but more like a campfire, or wood-based smokiness. Plus there eugenol, a guaiacol associated with the more medicinal qualities of peat (usually extracted from essential oils). Temperature affects the level of all molecules during the kilning process: increasing the temperature from 400 to 750 degrees Celsius during kilning increased phenol and cresol levels, but reduces guaiacol levels. Yet cresols are more abundant than phenols in the final spirit than in the barley malt (prior to milling and mashing). Furthermore phenols can be introduced through un-peated kilning, too.
It would seem that describing something as "peaty" is just not enough.
Another citation brought me to this other article from The Journal of the Institute of Brewing & Distilling entitled "Measurement of Thresholds for Reference Compounds for Sensory Profiling of Scotch Whisky" (Vol. 106, No. 5, 2000, pp 287-294). While phenol, cresol, and eugenol are not mentioned, this research looks at the detection and recognition levels in ppm of certain aromatic molecules - guaiacol being one in particular. The detection threshold for guaiacol was between .03 and .09 ppm, while the recognition threshold is between .7 and 3 ppm. While this research doesn't look at the point at which ppm hits an apex, (as in beyond a certain ppm, there is no distinguishable difference), I find it a little absurd that we have such heavily peated whiskies (i.e. Octomore) if one phenolic compound (i.e. guaiacol) is recognizable at a much lower level?
So what do we have in the end here? In my opinion, we have to be a bit more specific when we talk about our "peaty" scotches. Do we want something smoky, that has been aged longer or been in a barrel with a deep char? Or something that was kilned at a very high temperature and reeks of tar? Or do we want a medicinal or "vegetal" whisky? All very important things to consider when you are looking for your next scotch - especially an Islay.