Of Barley, Malt, and Peat

The marketing materials produced for spirits companies commonly appeal to tradition. Our Scotch must be good, the implicit (or explicit) message is, because our master distiller has inherited hundreds of years of knowledge from many, many generations of master distillers. We've been making whisky in exactly this way since God was a boy. Well, it's all a bunch of bull. You wouldn't want to drink what Scotch distillers made in 1800: it would be harsh, unaged, and full of headache-inducing congeners and non-ethanol alcohols. Everything about it, except the site of distillation and possibly the water used for it, would have been different, including the type and size of the stills, the varieties of the barley, the way the barley was malted, the way it was dried, and the types of barrels used. Distillers constantly tinker with everything about their process in an attempt to improve the taste of the whisky they produce, to make the process more efficient, or both.

Take barley, for example. No modern distiller could stay in business using the varieties of barley that were common in Scotland in the 19th century. There simply wasn't enough starch in those barleys to convert into alcohol in an efficient manner today. For time immemorial, man has genetically engineered the crops he plants, but the pace of genetic engineering barley (and many other crops, of course) accelerated dramatically in the 20th Century with the advent of academics and industry-funded institutes whose purpose in life was to make barley better -- more weather- and insect-resistant, higher in starch, higher in potential alcohol, and whatnot. The first barley variety to take Scottish agriculture by storm was Golden Promise, which was developed in the 1960s and withing a few years accounted for more than 90% of barley plantings in Scotland. By the mid '80s, though, it had been superceded by other varieties. Currently, the most prevalent barley variety is named Optic, although it will undoubtedly be made obsolete by something better within a few years. Some "tradition-minded" distillers still use older barley varieties, but the likelihood of those varieties being older than Golden Promise is vanishingly small.

Yeast plus starch equals not much. Yeast plus sugar equals alcohol. Grain has lots of starch and little sugar. Converting that starch to sugar is essential for producing something that can be fermented, which can then be distilled. For Scotch, that conversion is accomplished by malting the barley. This means steeping the barley in water to cause it to germinate, which releases enzymes that convert the starch in the barley to sugar. After germination, the process has to be stopped to keep the barley grains from growing into new barley plants. Not only that, but the malted barley has to be dried to prevent it from rotting. This is done by heating the malted barley in a kiln. Traditionally in Scotland, this was done in kilns fired by burning peat. Now, it mostly is done by coal- or gas-fired kilns. It used to be that each distillery would do its own maltings. This is now rare -- most malt today is now bought from one of the huge commercial malters like Port Ellen.

Peat-dried malted barley gives a distinctive smoky aroma and flavor to some Scotches, most famously those from Islay. The peatiness of a whisky is measured by the parts per million of phenols it contains (I have been unable to find out exactly how the ppm of phenols is measured or whether it is measured in the malted barley or in the finished spirit). Ardbeg, generally acknowledged to be the peatiest of the widely-released Scotches, has around 50 ppm of phenols. Laphroaig has 40 ppm, and Caol and Bowmore have around 35. Not all of the phenols come from the barley -- because water on Islay filters through peat bogs there, whisky made from unpeated barley but Islay water will still have 2 ppm of phenols. It is possible to make something much peatier than Ardbeg, and in fact Bruichladdich has -- an experimental bottling that contains 167 ppm of phenols. I also don't know how this is achieved: do they smoke the barley longer, or do they use a higher proportion of peat-smoked barley? And do the peated malts of today use a certain percentage of peated barley and a certain percentage of unpeated barley? Hopefully I will be able to figure this out soon. Stay tuned...