Saturday, May 18, 2013
Are you a fan of single-malt Scotch whiskey? Find out how it’s made
It takes more than three years to get to that fancy little glass of yours.
Single malt Scotch whisky is perhaps the best known and most highly regarded type of whisky in the world. It is Scotland’s most famous export and is held in high esteem by connoisseurs the world over. But what is single malt Scotch? Scotch is simple in that it contains only two material ingredients: malted barley and water. Scotch is complicated by the complex science that goes into its creation and by the variety of spirit that is produced all over Scotland. To be both simple and complicated at the same time is paradoxical, and paradoxes must be explored to be understood. Understanding Scotch is a tall order; an order that neither science nor philosophy can honestly claim to have achieved, though there is merit in the effort nonetheless. Such a drink begs to be appreciated, and that means first appreciating the time, effort, and knowledge that go into creating it.
All Scotch malt whisky is made from malted barley. The terms “malt” and “malting,” refer to the process of steeping the barley in water to kickstart germination and develop enzymes that will be crucial to the creation of alcohol during the fermentation phase of whisky making, with the goal being to maximize the total fermentable output of each barleycorn. The barley steeping process consists of soaking the barleycorns in water until they have absorbed water sufficiently to develop the essential enzymes for optimum alcohol production. As each microscopic part of the barleycorn absorbs water at different rates, steeping is a very scientific and tightly controlled process. According to Timothy C.S. Dolan in Whisky: Technology, Production, and Marketing, the steeping process can take just over two days. When the steeping has finished, the barley must be dried in a process called kilning, which is essential to the characteristic flavor of most Scotch whiskies. In the majority of Scotch distilleries, peat has historically been burned to dry the barley.
In modern times, many distillers will use a different heat source for drying and burn peat simply for its flavor characteristics. The peat smoke carries many aromatic and flavorful compounds -- known as phenols -- to the barley in much the same way that smoke is used to flavor barbecue. Because peat is decayed organic matter, it contains the properties of the land it came from and of the plants that grew in that land and transmits some of those properties to the barley and, ultimately, to the finished whisky. Different regions will produce different peat, which is to say that terroir plays a role in whisky production. Peat will vary from one bog to the next, but shows much more dramatic differences between regions. For instance, peat from inland areas will differ significantly from peat on the coast or on an island where seawater and sea air will have an effect. Peat is a major factor in the flavor of Scotch whiskies and produces particularly strong flavors in the whisky producing islands like Islay. When the malts have been dried and been infused with phenols from peat smoke, the distiller is ready to begin the next phases of the operation: milling and mashing. Milling reduces the grain to grist that can be mixed with water to create a mash. Mashing finally prepares the malt for fermentation through a process called wort recovery. According to Dolan, water is added to the mash in precisely controlled amounts and at precisely controlled temperatures enabling enzymes to break the natural starches in the grain down into the sugars that make fermentation possible.
When malting, milling, and mashing have been completed, the fermentation process can begin. The primary ingredient for effective fermentation is yeast. According to Iain Campbell in Whisky: Technology, Production, and Marketing, it used to be common for distillers and bakers to use yeast from breweries. However, over time bakers began using yeasts cultivated specifically for bread, causing distillers to follow suit and begin using yeast made specifically for whisky production. There is quite a bit of biochemistry involved in fermentation, but at a basic level yeast causes the creation of ethanol and carbon dioxide. Campbell points out that ethanol is produced to roughly half the amount of fermentable sugar, making sugars 50 percent efficient for alcohol production. With that knowledge, a distiller can gain a good idea of the alcohol content of the fermented product -- brewers and winemakers surely know the same fact. Another important contribution of yeast to whisky is that yeast fermentation creates many of the congeneric compounds that give flavor to whisky. Hundreds of congeners have been identified in whisky. As they are each different chemical compounds, some are more volatile than others and will boil at different temperatures during distillation. This means that not all of the congeners present in the fermented product will make it into the finished malt. This is not a bad thing as not all congeners imbue the whisky with pleasant flavors or aromas. Some will be removed naturally during distillation and others during aging and, in some cases, through chill-filtration.
When fermentation is complete, distillation begins. Distillation of malt whisky in Scotland is nearly always a two stage process; though some Scotch distillers, like Auchentoshan, choose to triple distill their whisky -- a practice that is typically associated with Ireland. For most of history, all whisky was, by necessity, made in pot stills. While many distillers do use the more recent invention of continuous stills, most single malt whisky is the product of pot stills. Simply put, the still is a pot with a coiled tube at the top known as a worm.
Scottish malt distillers use two stills: the wash still and the spirit still. The fermented wash is dumped into the wash still and heated so that the alcohol present in the wash will begin to boil in the pot. As the vapors rise through the worm, they are condensed back to liquid and form the distillate. The useful product of the wash still is known as “low wines.” According to Denis Arthur Nicol, the low wines amount to roughly one third of the original wash volume that went into the still. From here the low wines proceed to the spirit still. In any distillation, the first and last liquids to run from the still are not suitable to continue to the next phase of the operation. The early still output, known as foreshots, are as high as 85 percent ABV. After several minutes the foreshots emerge at roughly 75 percent and water is added. Nicol points out that the introduction of water creates a milky liquid due to fatty acids that are not water soluble. However, these fatty acids are soluble in the spirit, so as the spirit and the water combine, the strength comes down and the milkiness disappears (a similar murkiness is observed when water is initially added to a non-chill filtered whisky). It is at that point that potable, useful spirit emerges and distillation is complete. Just because distillation is complete does not mean that the whole process is over; spirit must age in a barrel for at least three years before it can be called Scotch.
Maturation through barrel aging is the final stage of production and results in a drink that is ready to bottle. It is not known when the benefits of barrel maturation were discovered, though Neil M. Gunn points out in Whisky and Scotland that the 6th century Welsh poet Taliesin wrote of mead being cellared in “The Song of Ale,” suggesting that the practice of intentionally aging drinks predates whisky itself. Maturation serves dual purposes: it adds flavors from the barrel wood and it significantly mellows the strong and pungent spirit into a smooth, drinkable beverage. While many types of barrels have been used in the past, the contemporary industry has settled on used casks from bourbon distillers and from makers of sherry. To say which type of barrel produces the best flavors is a matter of individual preference, but most Scotch distillers use bourbon casks because of availability. Because American law requires bourbon distillers to always use new casks, there is an abundance of used ones that are of no practical use to bourbon distillers, creating a buyer/seller match made in heaven between American and Scottish distillers.
Though some distillers, like Deanston, use brand new charred oak bourbon barrels, they are the exception to the rule. What may be confusing to drinkers, particularly Americans familiar with bourbon, is that the Scotch industry will often refer to using first-fill bourbon casks. What they mean is that they were the first to fill them with Scottish spirit as Kentucky distillers certainly filled them first. Whether bourbon or sherry, all of the casks are oak, primarily American white oak as it is abundant and less porous than some of the European varieties. All casks are heat treated, though bourbon casks more than others as law requires them to be charred. The heat treatment leads to flavors, like vanilla or caramel that are typically associated with drinks aged in oak and particularly with bourbon. These oaky flavors are the product of sugars in the wood that are caramelized during the heat treatment. The original contents of the cask also inform the Scotch during aging by influencing both flavor and color, with whiskies aged in Sherry casks generally being darker than other whiskies. With each fill, casks lose some of the characteristics that make them useful for aging, meaning that Scotch whiskies nearly always have older age statements than bourbon whiskeys and that the barrel will become useless as anything but a storage vessel. It is only after a period of years -- ranging from three years to 50 and beyond -- that a whisky is ready for bottling and distribution.
After all of the effort and skill that go into making a single malt whisky, it is fortunate that there is so much of it and that it is not more expensive. However, most single malt whisky will not go to market as a single malt but will be sold to blenders like Johnnie Walker and Chivas and arrive in your glass as only one of many constituent parts of a markedly different drink. Whether it is enjoyed on its own as a single malt or blended together with other whiskies, single malt Scotch is the foundation of the Scottish beverage industry. It is simply amazing that so much variety can come from one drink, made from one recipe. Single malt Scotch is a truly complex spirit. It is probably not possible to drink Scotch with the same care and attention that goes into making it, but that shouldn’t prevent one from trying.
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