Michelle Tostado
WRIT 340
26 February 2013
MWF 11:00 a.m.
Whisky Engineering: As Complex as the Flavors in the Glass
Abstract
The world of whisky making is a sensational place with an assortment of techniques,
flavors and bold characteristics. While there is no single chemistry composition that
identifies whisky, whiskies contain hundreds of compounds that give each whisky its
distinguishing taste. These different compounds and essences within the whisky arise from
the diminutive variances in the fundamental phases of the whisky production process.
Whisky’s most vital flavors come from the framework of raw material, distillation process,
and the maturation. It has been made for centuries, but in today’s scientific era, scientists
have played an imperative role in understanding and perfecting the whisky making process
through scientific analysis.
Introduction
There is much speculation as to who was the ingenious creator of the intricate spirit.
It has been established that the Celts were one of the first whisky makers in history and
even St. Patrick has been accredited with distilling the first whisky using primitive
equipment [1]. Another on going debate behind whisky’s history is whether it was first
produced it in Scotland or Ireland. What is acknowledged is that the Gaelic meaning of
whisky is “water for life” [1]. Whisky and whiskey are different spellings of whisky that are
referred to mean the same spirit. Whisky is commonly referred to whisky crafted in
Scotland, Canada, and Japan [1]. Meanwhile whiskey is produced in Ireland and the United
States. (For uniformity purposes, whisky will be referred to all kinds of whisky and
whiskey.) As with its origins, there is a wide variance in the fundamental steps behind the
production of whisky, but it’s creating follows the same basic techniques of malting and
mashing, fermentation, distillation, and maturation. These basic procedures are
fundamental in developing the stout flavors and aromas in a good whisky.
Malting and Mashing
The intricate process begins by making the malt mixture. The mixture is composed
of the desired grain (or mixture of grains) and water. Infinite combinations and varieties of
grains could be used in order to produce various tastes in whisky. Scotch whisky is made of
one hundred percent malted barley, whereas, other types of whiskey are made from a
mixture of barley, rye, wheat and/or corn [2]. Barley is the fundamental grain used in the
whisky making process because it induces the germination in the grain. During malting
process the grains are steeped in hot water and this activates the malt enzymes in the
barley to convert the grain starches into fermentable sugars. The barley’s maltase enzyme
breaks down the grain’s stored starches into disaccharide maltose and other sugars [3]. As
the grains being to sprout they are removed from the water and left to germinate.
After three to five days of germination, depending on the whisky maker’s
preferences, the grain is dried to discontinue the process. This is done to stop the grain
from growing too big and using up all the sugars that will eventually become alcohol [3].
Normally, the grain is dried in a kiln. To create a dark smoky flavor, whisky distillers smoke
their malt by drying it over a peat filled fire. The peat was originally used because of its
easy accessibility and low cost, but it has been found that the phenolic composition in peat
gives a smoky flavor to the whiskey [2]. There is wide range of smoky flavors that the peat
gives the whiskey, due to the wide variety of peats grown and their chemical interaction
with the whiskey solution.
The malt mix created is now ready to go on to the next step, mashing. The malt is
finely grinded and mixed with hot water. The aim is to turn as much of the grain’s starch
into as much sugar as possible in order to get the highest yield of alcohol within the batch.
By grinding the malt, the smaller grains have more surface area contact with the water,
which would help break down the grain’s sugars and chemicals [2]. The sugary mixture is
referred to as wort.
Fermentation
Fermentation is the biological process in which sugars such as glucose, fructose, and
sucrose are converted into ethanol and carbon dioxide [4]. The previously made wort is
mixed with yeast and allowed to ferment. The yeast feeds on the sugar in the wort solution
to create ethanol [2]. The fermentation process can take up to three days to complete.
There is no exact time in which the whiskey fermentation is ready because of the
varying factors that contribute to the whiskey composition. A way to know when the
fermentation is complete is using a hydrometer. A hydrometer measures the density of a
liquid relative to the density of the water [4]. The distiller then takes a sample of the
fermented whisky solution and measures it using a hydrometer. A reading is taken once a
day for three days and if the reading stays the same, it is a sign that the fermentation is
completed [3].
Distillation
The distillation process is a fairly simple process that is one of the key factors in the
resulting flavor of the whisky. A simple distillation process in a chemical laboratory is
shown in Figure 1, which shows the fundamentals of the distillation process. During
distillation, the fermented mixture is heated to separate the varying fraction components of
the mixture based on their volatilities. As the
solution is being boiled, the steam mixture
travels up the column. The fractioning column is
usually packed with marbles, ceramic pieces, or
copper mesh so that the vapors can condense back
down though the surface of the material. The higher
Figure 1: Simple Distillation Process in a
laboratory setting
volatile compounds travel out of the column and
into a condenser where it is cooled down back into a
Wikipedia
liquid state and collected. The less volatile components travel up the column and
recondense in the column and flow back to the boiler and the process keeps occurring.
When the temperature reaches the less volatile compound’s boiling point, the low volatile
compound travels through the column and into the condenser like the higher volatile
compounds.
The distillation process in whisky creation gives three different factions: foreshot,
spirit fraction, and the feints. The foreshot contains the highly volatility compounds; the
spirit fraction is the solution that will be matured into the final whisky product and the
feints contains the low volatility products [3]. The foreshot and the feints are removed
during distillation. Since the foreshot and the feints contain some alcohol in them, they are
sometimes recycled and redistilled a second time. The number of times the solution
mixture is distilled depends on the type of whisky being produced. The American whiskey
is usually only distilled once, leaving more of the flavor compounds remaining in the
whisky [3]. Scotch whisky is distilled twice and the Irish whisky is distilled three times [3].
Irish whisky producers distill their whiskey three times to market their whisky’s purity. No
matter how many times the solution is distilled, the distiller’s job is to collect the distillate
spirit at the right time. If it is collected too early, the low boiling compositions make the
whisky unfit to drink because the flavor compositions are undeveloped; if collected too
late, the high boiling sulfurous compositions would make the whisky unfit to enjoy [3].
When the whisky is distilled for the correct period of time, it has fruity and flowerysmelling esters and low concentration of feints [4]. After distillation, the whisky solution is
colorless [3].
Maturation
The distilled spirit is then poured into barrels to mature. The casks are made of
American white oak, which have previously been used to make bourbon. They have been
previously used because American white oak has a high concentration of vanillin, which
gives a vanilla flavor [2]. When the cask is first used to make bourbon, the bourbon absorbs
most of the vanillin, which gives bourbon its distinct vanilla flavor [2]. The American white
oak barrels are then charred on the inside and then reused to make the whisky giving a
more subtle and light discrete vanilla essences. The casks are made no greater than 700
liters [2]. The size limitation is established to create more contact surface area between the
whisky and the wood cask.
There are many different chemical reactions during the maturation of the whisky in
the barrels that change the favor of the whisky. The casks are charred on the inside before
the spirit solution is poured into it. When the inside is toasted, there is an added layer of
active carbon that removes unwanted pungent sulfurous compounds [2]. The charring also
increased the production of whisky lactones, which introduce fruity flavors and aromas like
coconut [2]. The charred barrel also gives the whisky its golden brown color. The
melanoidins, from the break down of cellulose in the cask, is the specific compound that
gives the gilded color [2]. During the maturation process there is some whisky that
evaporates from the barrel. This is comically referred to as the “angel’s share” [2].
There are governing laws that govern how long the whisky is left to mature. In the
United Kingdom, the Scotch Whisky Act states that whisky must be matured for at least
three years in Scotland for it to be considered Scotch Whisky [2]. This law governs in the
United Kingdom, Scotland, and Wales. The whisky from Scotland is matured for at least
three years because the weather is cold and damp, which affects the maturation because
the ethanol concentration goes down [2]. On the contrary, during the maturation process
in the United Sates, the ethanol concentration in the casks goes up because of the warmer
and dry climate. When maturing a whisky, it is important to find the essential balance
between the spirit character and the maturation [2]. This is why most whiskies are
matured for more than three years. Whisky maturation usually ranges from any where
between eight to twenty one years.
Once the whisky is matured, it is blended and diluted before it is bottled. A Master
Blender is a person that is able to detect hundreds of flavor compositions simply by their
nose alone and is in charge of mixing whiskies together to form the perfected blended
whisky [2]. Most whisky sold commercially is blended whisky, which is why a skilled
master blender is necessary to create consistency between the final whiskies. Single cask
whisky, spirit from a single barrel, is very rare to find. Depending on the whisky, whiskies
from different casks or distilleries are blended to create a unique flavor. It is upon the
whisky maker’s and Master Blender’s preferences on what mixtures of whisky are blended
to create unique aromas and flavors. The average concentration of alcohol content in a cask
before dilution is about sixty percent alcohol by volume, whereas the final product that is
sold by the bottle, is only about forty percent [1]. Therefore, the whisky product in the cask
also needs to be diluted to create the final whisky product.
Scientific Inquiry
Over the last decades, food scientists and chemical engineers have been studying
different whisky variations to analyze the chemical compounds that make a whiskey
unique. Unfortunately, a simple method to determine a correlation between sensory
characteristics and chemical composition of the whisky has not been found [5]. This is
because the flavors of whisky consists of a massive number of carbonyl compounds,
alcohols, carboxylic acids and the esters, nitrogen- and sulfur-containing compounds,
phenolic compounds, terpenes, and oxygen-containing heterocyclic compounds [5].
Researchers at the University of California Davis have managed to distinguish separate
whiskies from different countries, such as a scotch whisky from an American whisky [1].
The researchers use high performance liquid chromatography and high-resolution mass
spectrometry to separate different components in a whisky solution and tell scientists
some facts about their compositions, such as molecular weight and about their structures
[1]. It is harder to distinguish between whiskies of certain regions, such as different regions
of Scotland, due to the similarity in the whisky making process and the types of grains used.
The German Research Center for Food Chemistry used gas chromatography and aroma
extract dilution process to identify more than forty aroma compounds that contribute to
the whisky’s fruity, smoky, and vanilla like odor profiles [6]. Despite the tedious and timeconsuming process of analyzing various whisky compositions, scientists and researchers
are continuing to find new compositions not previously detected in whisky.
Conclusion
The process of manufacturing whisky has existed for centuries, but modern
scientific instrumentation, researchers, scientists, and whisky aficionados have tried to
understand the under-laying scientific fundamentals behind crafting whisky.
Comprehending the chemical compounds created in the multiple reactions when making
whisky has led to variations in the processes and brought forward layers of complexity
behind the uniqueness of the hundreds, if not thousands of different whiskies.
Works Cited
[1] F. Diep. (2013, September 9). Chemical Analysis Finds A Whiskey's Unique Fingerprint
[Online]. Available: http://www.popsci.com/
[2] V. Gill, “A whisky tour,” Royal Society of Chemistry, vol. 5, no. 12, pp. 40-44, Dec. 2008.
[3] B. Halford, “Whiskey – It takes complex chemistry and lots of water to wee dram of this
ancient spirit,” Chemical & Engineering News, vol. 83, no. 20, pp. 38-38, May 2005.
[4] Anonymous. (2012, January 24). How to Make Whiskey – Step by Step [Online].
Available: http://howtomakewhiskeyhq.com/
[5] H. Maarse, “Distilled Beverages,” in Volatile Compounds in Foods and Beverages. New
York: Marcel Dekker, Inc., 1991, ch. 17, pp. 574-574.
[6] Anonymous, “What’s in a whiff of whiskey?,” Chemical & Engineering News, vol. 86, no.
30, pp. 50-50, Jul. 2008.