The production of malt whisky is a science, but it is not an exact science, and there is more than a trace of superstition running throughout the industry. There is an art to the process, and a little magic. There is a belief among Distillery Managers that any trivial change can influence the taste of the product.
Malt production uses only three basic ingredients — yeast, water, and barley — yet there is an incredible variety in flavour profiles.
Yeast is a crucial ingredient — it triggers the chemical process that converts barley into alcohol — but it has the least affect on the flavour profile of the product (the process of fermentation has an effect, but the yeast used is not significant).
A reliable water source is essential for the production of malt whisky; fortunately, in Scotland, plentiful rainfall year-round provides an abundant supply. Water is used in all phases of production: beginning with malting, and continuing through mashing, and at the end of the process for the reduction of ABV (except, of course, in ‘cask strength’ bottlings).
The source of water used by the distillery is a key factor in the flavor of the whisky produced: adjoining distilleries that use water from differing sources produce products with distinctly different personalities. For instance, water in the Highlands — and, in particular, Islay water — flows through peat regions, which impart minerals that give the water unique flavours: many distilleries remove mineral impurities with de-ionization techniques, but other distilleries use the hard water because of the unique personality it imparts to the product.
Barley crops thrive in Scotland because of abundant precipitation and moderate temperatures year-round; even in summer the temperature is rarely above 20° C and there is enough rainfall to keep the barley crops healthy.
Historically, most distilleries harvested their own barley, grown on-site; alternately, the barley would be purchased from local farmers. As the years slipped by, barley production became a specialty commodity and more economical methods of barley production were discovered. Barley crops became an industry, which now sells in bulk to distilleries.
Barley was a hit-and-miss crop until 1965, when Golden Promise was developed by exposing a barely variety to gamma radiation. Golden Promise is a hardy, fast-growth grain, which produces a sweet, clean flavour. Since then, genetic engineering has transformed Golden Promise into new varieties (e.g.: Optic and Chariot), but many claim that the new varieties do not provide the desired malting personality of Golden Promise. Some distilleries (e.g.: Macallan) still use Golden Promise, but it is getting difficult to find, and — as the yields are much higher with the new genetically modified barley, and producers prefer these high-yield strains — it is improbable that distilleries can now claim 100% pure Golden Promise barley as an ingredient. If you can afford a well-aged Macallan — say 17 or 18 YO — the taste might be worth the price.
It could be argued that peat is an ingredient, but not all malt whiskies are peated, so I’ll discuss peat in a future post, when I delve into the malting process.