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Whisky (whiskey) is one of the most popular spirit-based drinks made from malted or saccharified grains, which should mature for at least three years in wooden barrels. High popularity of products usually cause a potential risk of an adulteration. Regarding to that fact the authenticity assessment is one of the key elements of food product marketing. Authenticity of whisky is based on the comparison of composition of this alcohol with other spirit drinks. This paper summarizes all information about the comparison of whisky and other alcoholic beverages, the identification of type of whisky or the assessment of its quality and finally the authentication of whisky. The work also presents the various analytical techniques for analyzing whisky such as: gas and liquid chromatography with different types of detectors (FID, AED, UV–vis), electronic nose, atomic absorption spectroscopy and mass spectrometry. In some cases the application of chemometric methods there are also described, namely: PCA, DFA, LDA, ANOVA, SIMCA, PNN, k-NN, CA, and preparation techniques such SPME or SPE.
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CHEMICAL COMPOSITION ANALYSIS AND AUTHENTICATION OF
WHISKY
Paulina Wiśniewska*, Tomasz Dymerski, Waldemar Wardencki, Jacek Namieśnik
* p.m.wisniewska@gmail.com
Department of Analytical Chemistry
The Chemical Faculty
Gdansk University of Technology
11/12 Narutowicza St.
80-233 Gdansk, Poland
This article has been accepted for publication and undergone full peer review but has not
been through the copyediting, typesetting, pagination and proofreading process, which
may lead to differences between this version and the Version of Record. Please cite this
article as doi: 10.1002/jsfa.6960
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ABSTRACT
Whisky (whiskey) is one of the most popular spirit-based drinks made from malted or
saccharified grains, which should mature for at least three years in wooden barrels. High
popularity of products usually cause a potential risk of an adulteration. Regarding to that fact
the authenticity assessment is one of the key elements of food product marketing.
Authenticity of whisky is based on the comparison of composition of this alcohol with other
spirit drinks. This paper summarizes all information about the comparison of whisky and
other alcoholic beverages, the identification of type of whisky or the assessment of its quality
and finally the authentication of whisky. The work also presents the various analytical
techniques for analyzing whisky such as: gas and liquid chromatography with different types
of detectors (FID, AED, UV-Vis), electronic nose, atomic absorption spectroscopy and mass
spectrometry. In some cases the application of chemometric methods there are also described,
namely: PCA, DFA, LDA, ANOVA, SIMCA, PNN, k-NN, CA, and preparation techniques
such SPME or SPE.
Keywords: whisky, authentication, chromatography, food analysis, e-nose
INTRODUCTION
Whisky (whiskey) is one of the most popular spirit-based drinks. Depending on the region,
whisky is defined differently. According to the European definition of whisky, it is a spirit
drink produced via distillation of mash made from malted grains or from grains which have
been saccharified by the diastase of the malt contained therein. Distillation is conducted at
less than 94.8 % vol. in order to retain an aroma and taste derived from the raw materials
used. Whisky should mature for at least three years in wooden barrels of a capacity not
exceeding 700 liters. The final distillate retains its color, aroma and taste derived from the
production process. Only water and plain caramel (for coloring) can be added to the distillate;
no other colorings and flavorings can be added. Scottish whisky is the most popular whisky
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type. It is produced entirely from malted barley via double distillation in large copper pot
stills. The volatile phenolic compounds, inter alia, cresol and guaiacol that form in roasted
barley are responsible for the specific taste of whisky. Whisky originating from the northern
part of the USA is made from the mixture of corn, rye, wheat, barley and other grains. It is
aged in oak barrels for at least two years 1-4.
Allegedly, whisky originated in Ireland where local monks were already producing distilled
alcohol known in Latin as aqua vitae (translated to Gaelic as uisge beatha) in the 7th century.
It was a mixture obtained via distillation of fermented fruits, and used for medicinal purposes
only. In the 17th century, the shortened name uiskie started to be used, while in 1715, the
name was changed to whiskie. The present-day name “whisky” was established in 1736. In
the 9th century, the Irish monks and their medicinal alcohol reached Scotland. Information
about the water of life made from barley appeared in the mid-16th century. At the turn of the
18th century, the British Parliament taxed the production of whisky, which resulted in a
decrease of legal production and, obviously, an increase in illegal production of this spirit.
These circumstances stimulated the development of diverse whisky types produced by small
camouflaged distilleries, and the use of traditional recipes passed on through the Scottish
clans. As a result of this natural diversification, three types of whisky exist presently, i.e.
blended whisky, grain whisky and malt whisky. Blended whisky, produced via mixing of
grain whisky and single malt whisky, is represented by the brands such as, Johnny Walker
and Ballantine's. Grain whisky is made from the mash consisting of different grains, mostly
of barley, wheat and corn. It is produced via continuous distillation in a column still.
Actually, the only difference between grain whisky and vodka is that the former has to be
aged for three years in an oak barrel. Grain whisky made from one type of grain, so-called
single grain whisky, is also produced. In this case, either malted or unmalted barley can be
used. Malt whisky is made from malted barley. Its distillation takes place in copper pot stills,
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followed by maturation in oak barrels usually for over 8 years. Malted whiskies can be
divided into two groups, i.e. single malt whisky (malted whisky originating from one
distillery) and vatted malt whisky (a blend of single malt whiskies originating from different
distilleries) 5.
This article presents the methods for analyzing whisky composition which also enable its
authentication. The chemical composition analysis can be conducted be means of, inter alia,
chromatography and spectrometry as well as other techniques. The application of the
aforementioned methods enable authentication, the determination of exact composition, and
quality evaluation of whisky. Thanks to these procedures, it is possible to remove falsified
products from the market, and to select a whisky which will fulfill expectations.
ANALYSIS OF WHISKY COMPOSITION
Each spirit has a characteristic aromatic profile, which influences the processes of
fermentation, distillation and storage as well as the selection of an appropriate raw material.
The compounds responsible for the aroma are, e.g. fusel alcohols, fatty acids and esters.
Spirits are a diverse group therefore in order to determine individual qualities of a given
alcoholic beverage, it is necessary to determine its composition. Studies on the exact
composition of whisky are mainly performed by using gas chromatography. Such research
allows for finding characteristic compounds and defining aroma profiles, which can then be
used for defining the quality and authenticity of the tested whisky. Fitzgerald et al. 6
analyzed Scotch and Irish whiskies by means of gas chromatography coupled with a mass
spectrometer (GC-MS). Samples were prepared by solid-phase microextraction (SPME).
Solid-phase microextraction (SPME) is based on the sorption of small amounts of samples
onto a thin cylindrical layer of stationary phase coating the glass or quartz fiber. The fiber is
placed inside the rust-free tube that is located in the syringe needle. Such set-up enables the
mass exchange during the enrichment and release of the adsorbed compounds, and prevents
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clogging. The extraction can be conducted by immersing the fiber directly in the liquid (DI –
SPME) or by placing it in the head space above the liquid or solid sample (HS – SPME) 7, 8.
The applicability of three fiber types was tested, namely, PDMS-DVB, CAR-PDMS and PA,
the latter being the most suitable for the procedure. Seventeen compounds were selected for
the analysis, including fusel alcohols, acetates and esters; however, the concentration levels
of six of them turned out to be below their detection limits in all samples. Despite this
situation, the applied technique was useful for quantitative analysis of the selected
compounds in whisky samples 6. This research allowed for defining a useful method, which
can then be used for analyzing compounds characteristic of whisky. Poisson and Schieberle 8
analyzed the composition of American Bourbon by applying High Resolution Gas
Chromatography – Olfactometry (HRGC-O). This technique allowed the detection of 23
active aroma substances. Based on the review of previously published data, it turned out that
13 of these compounds were never detected before, i.e. ethyl (S)-2-methylbutanoate, (E)-2-
heptenal, (E,E)-2,4-nonadienal, (E)-2-decenal, (E,E)-2,4-decadienal, 2-isopropyl-3-
methoxypyrazine, ethyl phenylacetate,
4-methylacetophenone, α-damascone, 2-phenylethyl propanoate, 3-hydroxy-4,5-dimethyl-
2(5H)-furanone, trans-ethyl cinnamate, and (Z)-6-dodeceno-γ-lactone. Thanks to the use of
olfactometry, it was possible to assign concrete aromas to the identified compounds 9. The
next article by Poisson and Schieberle 10 was a continuation of previous research and
included the quantitative analysis of 31 compounds selected from among the substances
which had already been detected via two-dimensional high resolution gas chromatography
coupled with a mass spectrometer (TD-HRGC-MS). The results obtained were used to
formulate the aroma characteristic for American Bourbon by mixing 26 compounds at
specified concentrations with the solution of water and ethanol 10. An aroma profile of this
kind can be used to differentiate American Bourbon from other kinds of whisky.
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Multidimensional gas chromatography coupled with mass spectrometry and olfactometry
(MDGC-MS-O) was used by Wanikawa et al. 11 to identify green note compounds in malt
whisky. These compounds are characteristic of some kinds of whisky, which means that they
can be helpful in the assessment of the authenticity of tested products. The applied technique
allowed the detection of two aldehydes (i.e. E-2-nonenal and E,Z-2,6-nonadienal) and three
alcohols (1-octen-3-ol, 4-hepten-1-ol, nonan-2-ol) which are responsible for the green note
aroma. It was demonstrated that the green note whisky contains more aldehydes and nonan-2-
ol compared to other whisky types 11. Besides the attempts of identifying the exact
composition of the volatile fraction in whisky, the investigations of chosen groups of
compounds and single compounds were conducted. It is noted that some groups of
compounds have greater influence on the aroma of whisky. Esters are an example of such a
group. Camp et al. 12 used two-dimensional gas chromatography coupled with the mass
spectrometer (GC-GC-MS) in order to analyze ethyl esters in
whisky 12. These compounds mainly form during the fermentation and aging processes.
Esters are characterized by intense aroma and the low value of odor detection threshold.
Depending on the concentration of esters, they may have a positive or negative effect on the
aroma of an alcoholic beverage. For example, ethyl acetate at high concentrations gives
solvent-like or vinegar note to the final product, while at low concentrations, it softens the
sharp aroma of other beverages 13. Because of that it is of utmost importance to quantitatively
analyze this group of compounds. In order to preconcentrate the analyzed compounds in
samples, solid phase extraction was used (SPE) 12.
Haloanisoles were another group of compounds studied by Campillo et al. 14. These
compounds form in whisky aging in oak barrels. Their monitoring may enable an assessment
of the ageing process and, as a result, verification of the authenticity of the age of whisky.
The study results demonstrated that solid-phase microextraction coupled with gas
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chromatography and atomic emission detection (SPME-GC-AED) is a perfect system for
monitoring the contents of 12 selected haloanisoles 14. A class of phenols is among the
compounds investigated in whisky. This is connected with their different contents in
individual types of whisky. Twelve substances belonging to phenols were analyzed in the
samples of whisky originating from Scotland (15), Ireland (1), USA (4), Canada (1), Japan
(5), Spain (1), Argentina (1), New Zealand (2) and India (1) by using GC-MS. As a result,
2,4-dimethylphenol was detected in the volatile fraction of whisky for the first time. The
main difference between the samples from specific countries was in the concentration of o-,
m- and p-cresol. The highest concentration of these compounds was determined in whisky
from Scotland. Moreover, the samples of Scottish, Canadian and Bourbon whisky were
compared. The highest concentration of phenols was found in Scottish whisky, while the
lowest one, in Canadian whisky. On the other hand, the highest concentration of eugenol was
observed in Bourbon whisky 15. It is concluded from this article that an analysis of the
presence of selected phenols and their total amount can be used for distinguishing whisky
according to its geographical origin. Apart from selected groups, also individual compounds
are analyzed with the presence being characteristic of selected spirits. Among the analyzed
single compounds were γ-lactone 16, ethyl carbamate 17, 18 and methanol 19. Lactones are well-
known organic compounds which display diverse biological effects, e.g. anticancer, antiviral,
antibacterial and anti-inflammatory activities, etc. Lactones have also been recognized as the
components of taste and aroma in alcoholic beverages, mainly in whisky, wine and cognac.
The characteristic odor of the famous Japanese sake results from the presence of sotolon 20. γ-
lactones are responsible, to a large extent, for the aroma of whisky. Wanikawa et al. 16
conducted a study whose aim was to identify the compounds responsible for “sweet” and
“fatty” aromas in malt whisky from Scotland. The analysis was performed by using GC-MS
and GC-O. It has been determined that γ-decalactone and γ-dodecalactone are responsible for
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“sweet” and “fatty” aromas, respectively 16. Ethyl carbamate is another compound which
should be analyzed in alcoholic beverages. This is needed due to its influence on the quality
of the product. Ethyl carbamate (EC) is a natural compound that occurs in fermented foods
and alcoholic beverages such as, bread, yoghurt, soy sauce, wine, beer, and particularly in
spirits made from stone fruits and stone-fruit pomace (e.g. cherry, plum, mirabelle plum and
apricots). Research has demonstrated that ethyl carbamate has a carcinogenic effect in
laboratory animals. The International Agency for Research on Cancer has classified EC as
possibly carcinogenic to humans 21, 22. Ethyl carbamate was analyzed in alcoholic beverages,
inter alia, in whisky by means of gas chromatography coupled with tandem mass
spectrometry (GC/MS-MS). The technique was tested for its suitability to determine low
concentrations of EC. Five samples of whisky were analyzed; the detected level of ethyl
carbamate varied from 60 to 330 ppb 17. EC was also analyzed in Scottish whisky by using
GC-MS. Five types of blended whisky, including two deluxe and two malt whiskies, were
investigated. A total of 229 samples were processed. The mean concentrations of ethyl
carbamate in specific whisky types were similar, except for deluxe whisky which had higher
EC content 18. Methanol is similar in this respect. This is also a toxic compound, which must
be monitored due to its influence on the quality of whisky. The presence of methanol was
investigated by means of an electronic nose 19. The electronic nose is an analytical device
used for the fast detection and identification of odorant mixtures; its mode of operation
mimics the human sense of smell. The electronic nose employs specific chemical sensors
which generate a characteristic aroma profile, a so-called fingerprint, in response to being
exposed to the investigated gaseous mixture. The identification of mixture components is
based on the comparison with reference profiles 23. Wongchoosuk et al. 19 used the electronic
nose equipped with carbon nanotubes (CNT) to investigate the samples of whisky tainted
with different amounts of methanol. Principal component analysis (PCA) was used to analyze
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the obtained data. The principal component analysis (PCA) is based on transformation of the
original variables to new variables. The PCA provides a rotation of the coordinate system to
maximize the variance of the all the coordinates. The PCA is mainly used to model, compress
and visualize data 24. The applied method allowed the graphical identification of methanol-
free whisky and whisky containing methanol at four different methanol concentrations.
Distinguishing among specific methanol concentrations in the samples was also possible
thanks to the application of PCA 19. Besides the concentrations of organic compounds, the
contents of zinc, lead and copper ions was also determined. The presence of inorganic
compounds is tested in connection with the quality of whisky as they can also influence its
aroma. Anodic stripping voltammetry (ASV) and atomic absorption spectrometry (AAS)
were employed in this study. In the case of whisky samples, ASV turned out to be a more
suitable method because it allowed the detection of all analyzed ions in all samples 25.
A COMPARISON BETWEEN WHISKY AND OTHER ALCOHOLIC BEVERAGES
Being one of the most popular alcoholic beverages, whisky is often compared with other
known spirits in relation to chemical composition. Such studies aim at establishing whether
different types of spirits can be identified by means of analytical techniques. For example,
Cardeal and Marriott 26 describe how cachaça, whisky, rum, vodka, gin, tequila and selected
liqueurs were identified by using two-dimensional gas chromatography. The specification of
compounds present in the sample matrix was prepared for cachaça and rum only. Whisky and
other spirits were compared based on the obtained chromatograms. In comparison to other
spirit-based beverages, whisky and vodka had the poorest chromatographic profiles.
Compounds belonging to alcohols, aldehydes, ketones, terpenes, aromatic compounds, esters
and acids were detected in the samples of whisky. The chromatogram representing whisky is
very poor in comparison to other obtained chromatograms 26. The electronic nose was also
used to compare different alcoholic beverages 27. There are electronic noses which combine
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the features of fast gas chromatography with the properties of an electronic nose. One
analysis conducted with such device supplies concurrent information about the sample
composition and the profiles of volatile fractions. Thanks to this, complete information about
the similarity between the given sample and reference sample is obtained. The electronic nose
coupled with fast gas chromatography was used to distinguish among vodka, tequila, whisky,
beer and wine. The statistical analysis was performed by using principal component (PCA)
and discriminant function analysis (DFA). Discriminant function analysis is used for
determining which variables allow for the best division of a given group of cases on naturally
occurring groups. Discriminant function analysis is used for classification of samples to
previously defined groups 28. The DFA method gave better results because it allowed for
distinguishing the types of alcoholic beverages, including four whisky brands 27. Apart from
comparing alcohols in relation to entire matrices, research was also conducted as regards the
comparison of the content of only some groups of compounds. Ng et al. 29 analyzed selected
acids and phenols (a total of 19 compounds) in whisky and cognac samples by means of GC-
MS. Moreover, five compounds, i.e. vanillin, syringaldehyde, coniferaldehyde, gallic acid
and vanillic acid were determined in samples of spirits of different age. In the case of Scotch
whisky, the chosen samples were 12, 17 and 30 years old. The other sampled whiskies were 6
and 12 years old. In general, the samples of oldest whiskies contained the highest
concentrations of the analyzed compounds. However, in the case of Scotch whisky, one
sample of 17-yr old spirit has lower concentration of coniferaldehyde than that measured in
the sample of 12-yr old spirit. This indicates that the relationship between the age of whisky
and the content of phenolic compounds is not a simple one 29.
IDENTIFICATION OF WHISKY WITH REGARD TO ITS TYPE, QUALITY, BRAND
AND ORIGIN
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Due to the high diversity of alcoholic products, the assessment of whisky with regard to its
brand, quality and origin is necessary. The study conducted by Lehtonen et al. 30 by means of
GC-FID and UV-Vis can serve as an example here. The obtained data were analyzed by PCA
method. The investigations were conducted twice by using different UV-Vis techniques. At
first, HPLC with UV-Vis detection was applied; the absorbance was measured in the
wavelength range from 220 to 520 nm. The concentrations of propanol, isobutanol, 2-methyl-
1-butanol and 3-methyl-1-butanol were determined by means of GC-FID. The samples of
whisky originating from Canada (2), Finland (3), Ireland (1) and Scotland (8) were analyzed.
Besides whisky, the samples of rum and brandy were also investigated. The results of UV-
Vis measurements did not supply sufficient information to distinguish among the whisky
samples with regard to the country of their origin. The second set of measurements
encompassed the absorbance determinations at a wavelength of 380, 440 and 500 nm made
with a spectrophotometer, and the concentration measurements of the aforementioned
compounds and methanol. The samples of whisky from Canada (2), Ireland (10) and Scotland
(15) were analyzed. As in the previous case, the UV-Vis analysis alone was not sufficient to
distinguish among the processed samples. This has become possible thanks to the application
of PCA to the results of GC-FID analysis 30. Gas chromatography combined with numerous
chemometric analyses is used for the analysis of whisky according to its geographical origin.
Three types of whisky, i.e. Scottish, Irish and Bourbon were distinguished by means of GC-
MS and different statistical methods. González-Arjona et al. 31 stated that the best results
were achieved with kNN, PDA, MLP and PNN methods. The kNN algorithm belongs to the
group of algorithms, in which the description of the classifier's target function is not
performed during the classifier's training, but at the stage of assigning an object to the
specific classes. The underlying principle of the classifier's operation is that the object
belonging to a specific class has in its close proximity other objects belonging to the same
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class. Classification in performed by comparing the fitted object to all objects stored in the
training set and then choosing from among the key defined k objects that are most alike 32, 33.
Artificial neural network involving multilayer perceptrons (MLP) is a multilayer one-
directional neural network. They are the most frequently used kind of ANN. An artificial
neural network mimics a biological neural network, which collects and transfers signals to the
central nervous system, processes the data, and makes specific decisions depending on the
identified objects. The basic elements of artificial neural networks are artificial neurons 33, 34.
Probabilistic neural networks (PNN) are a kind of artificial neural networks capable of
independent learning. When a new teaching standard, which may introduce additional
information of very important nature, becomes available, it is not necessary to start the
learning process from the beginning. It is possible to introduce such a new standard directly
into the network in the form of another radial neuron. This feature is very significant as it
allows the continuous operation of a PNN without any breaks for a long learning process 32,
33. The same whisky types were analyzed by González-Arjona et al. 35 by means of GC-MS.
The data were processed by PCA and CA methods. Cluster analysis is a method, which
allows for grouping elements described by more than one feature into relatively homogenous
classes. The most important part of CA is the formation of clusters, that is, the sets of objects
where the similarity between any two objects from the same set is higher than that between
any other object from the same set and any object not belonging to the set. The clusters do
not overlap, i.e. none of the objects can belong to more than one class. The clusters are
separated by a precisely determined distance, which can be defined in a number of ways 33, 36.
The contents of 1-propanol, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-
butanol were determined in the samples of 12 Irish whiskies, 20 Bourbons, and 26 single malt
Scottish whiskies. Thanks to the combined use of GC-MS technique and PCA method, it was
possible to distinguish among all the analyzed samples. Irish whiskies were the most compact
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group in the PCA graph which demonstrates that the four compounds selected for the analysis
are enough to distinguish Irish whisky from other whisky 35. Apart from verifying, whether it
is possible to define the county, from which whisky originates, tests were performed aimed at
verification as to whether it is possible to determine the region of origin of a given whisky.
Mignani et al. 37 analyzed 18 samples of Scotch whisky, which included 15 samples of single
malt whisky (10 samples from the uplands, and six samples from the islands) and three
samples of blended whisky. Each analyzed whisky was of different brand identity. The
samples were investigated by means of optical spectroscopy, while the obtained data were
analyzed by PCA and LDA methods. Linear Discriminant Analysis (LDA) is a statistical
method, which allows division into border areas by means of linear functions and works well
in data analysis. This is one of the data classification methods. Such methods are aimed at
determining class allocation of other tested objects described by the same or similar chemical
structural features 33, 38. The applied methodology allowed distinguishing among various
whisky types, i.e. blended whisky was distinguished from single malt whisky. However, it
was problematic to divide the samples based on the region of their origin. In the case of
whiskies originating from the uplands and islands, one sample in each region poorly fitted to
the model 37. In order to determine the region of sample origin and sample type, Adam et al.
39 attempted to use atomic absorption spectroscopy (AAS). Thirty-five samples of whisky
were analyzed; the samples differed with regard to distillery, the region of origin, whisky
type and vintage. The contents of copper, zinc, lead, nickel, iron, calcium, magnesium and
sodium were determined in the samples. The obtained data were statistically analyzed by
means of CA. It was demonstrated that the origin of whisky cannot be identified based on the
contents of the aforementioned compounds. However, malt whisky had much higher
concentration of copper than blended Scotch and pure grain whisky. This finding shows that
a simple analysis of copper content may allow distinguishing malt whisky from other whisky
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types 39. Various kinds of whisky and brandy were compared based on the ratio
of 2-methylbutanol to 3-methylbutanol by using the GC-FID technique. The analyzed whisky
samples included blended whisky (14), malt whisky (14), Bourbon (2), Canadian whisky (2)
and whisky originating from Denmark (3). The highest and the lowest content of both
analyzed compounds was determined in Bourbon and Danish whisky, respectively. The ratio
of 2-methylbutanol to 3-methylbutanol ranged from 0.32 to 0.44. Only two samples had
ratios of 0.32 and 0.33, while the ratio values for the remaining samples were greater than
0.36. This allowed distinguishing whisky from brandy because the ratio values in brandy
ranged from 0.19 to 0.33 40. Apart from testing the origin and kind of whisky, tests were
performed to distinguish between whiskies of the same kind produced by various brands.
Three well-known whisky brands, i.e. Black Label, Ballantine's and West Highlands were
analyzed by means of GC-MS, including sample preparation by SPME technique. The
microextraction technique was optimized with regard to the fiber type; CAR/PDMS fiber has
been selected from among the five evaluated fibers. The compounds detected in whisky
samples belonged to monoterpenes, higher alcohols, esters, fatty acids, carbonyl compounds
and phenols. Differences detected between specific whisky brands were mainly of
quantitative nature. In all analyzed samples ethyl esters were the most numerous group of
compounds. In the case of higher alcohols, it was observed that the concentration of 3-
methyl-1-butanol in Black Label whisky was definitely higher than that in other whisky
brands. The concentration of carbonyl compounds showed a similar pattern. The lowest
concentration of terpenes was determined in Ballantine's whisky. By using the sum of the
areas under the peaks attributable to specific compounds, it was possible to distinguish
among specific whisky brands 41. Apart from the aforementioned research, it was also
checked as to whether it was possible to distinguish between whiskies of different quality.
Such tests would be helpful in verifying the authenticity of high-quality whisky, which is
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often counterfeited with poorer-quality whiskies. In order to distinguish among Scottish
whiskies of different quality, a sensory evaluation and various statistical methods (PCA,
ANOVA and PLS regression) were employed by Lee et al. 42. Analysis of variance
(ANOVA) is a parametric tool that allows for comparing more than two groups, which had
been categorized based on one variable (one-way ANOVA). The underlying idea is to
compare the variance of dependent variables within the groups that had been created, based
on the values of independent variables 33, 43. The partial least squares method (PLS) combines
features of principal component analysis and multiple regression. First, a set of latent
variables is distinguished, which explain as much covariance as possible between
independent and dependent variables. Next, at the regression phase, values of dependent
variables are predicted using independent variable decomposition 44. The samples of blended
whisky were divided in the following categories: deluxe (11), standard (22), multiple retailer
(4), and West Highland (3). PLS regression turned out to be the best method for data analysis
because it correctly grouped all types of whisky, except for the West Highland type. The
dominant aroma of Deluxe whisky was described as fruity, buttery, malty and nutty, and also
vanilla, floral, pungent, sweet and smooth. The aroma of retailer whisky was evaluated as
solventy, soapy, rancid, grassy, mouldy, pungent, grainy, oily and spicy. The dominant
organoleptic qualities of standard whisky were characterized as oily, sulfury, rancid, grainy,
smooth, soapy, vanilla, solvent and sweet. West Highlands whisky was described as woody,
smoky, spicy, medicinal and sulphurs, mouldy, pungent, soapy and malty notes 42. Similar
research aimed at distinguishing among blended whiskies of different quality was conducted
by Lee et al. 45. The whisky samples were analyzed by using SPME-HRGC-MS, while the
obtained data were processed with the same statistical methods as before, i.e. PCA, ANOVA
and PLS regression. A total of 38 compounds was analyzed. Deluxe whisky was identified
based on the contents of ethyl hexanoate, ethyl heptanoate, ethyl acetate, ethyl nonanoate,
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ethyl decanoate, isoamyl decanoate and isoamyl hexanoate. The content of acetate esters
(dodecyl and phenylethyl esters, and 3-methylbutyl acetate) was used to identify standard
whisky. In the case of retailer whisky, ethyl hexadecanoate, ethyl octadecanoate, ethyl
tetradecanoate and propyl decanoate were the markers. West Highlands whisky was
identified by the presence of furfural, isobutyl octanoate and ethyl benzoate 45.
AUTHENTICATION OF SCOTCH WHISKY
Scotch whisky the most highly valued of spirits that is preferentially chosen by consumers. It
is produced almost exclusively in Scotland from malted barley or barley; Scotch whisky is
aged in wooden barrels for three years. The most popular scotch brands are Johnie Walker,
Teacher’s, The Famous Grouse, Chivas Regal, Laphroaig, The Balvenie and Ballantine’s.
The name “Scotch whisky” is a geographical indication assigned to Scotland; the term is
protected by international law. Genuine Scotch whisky has to be produced in Scotland
therefore the authentication of this spirit is of utmost importance. Scotch is the most
frequently falsified whisky thusScotch numerous studies on the methods of its authentication
have been published. Parker et al. 46 used gas chromatography-combustion-isotope ratio mass
spectrometry (GC-C-IRMS) to authenticate whisky. Eight samples of popular Scottish
whisky and two samples of other whisky types were compared. The carbon isotopic ratios
were analyzed for selected congeners, i.e. acetaldehyde, ethyl acetate, n-propanol, isobutanol
and amyl alcohol. The plotted graphs allowed distinguishing among the analyzed samples,
and finding the samples of falsified spirits 46. Scotch whisky was also authenticated by means
of GC-MS and HPLC 47, 48. It became apparent that the analysis of higher alcohols is the most
important part of such authentication procedures. Higher alcohols are the most representative
group attributable to whisky, particularly n-propanol, isobutanol and amyl alcohol 47. In the
second article 48, a number of qualities had been defined which scotch whisky should posses.
These qualities include, inter alia, the alcohol content not lower than 40%; methanol content
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lower than 25 g / 100 l; the sum of the contents of n-propanol and isobutanol at least 97 g/100
l; the ratio (sum of 2-methylbutanol and 3-methylbutanol)/ 2-methylbutanol not lower than
1.9 and not higher than 3.5; and the ratio of 3-methylbutanol to 2-methylbutanol not lower
than 2.2 and not higher than 3.5. All the aforementioned properties allow the authentication
of Scottish whisky 48. MacKenzie and Aylott 49 decided to check whether the UV-Vis
technique can be used to authenticate whisky produced in Scotland. To this end, 35 samples
were analyzed of which 20 were suspected to be Scottish whisky and the remaining 15
samples to be other whisky types. In order to confirm the UV-Vis results, gas
chromatography was also used as it has been previously assessed as suitable for the
authentication of Scottish whisky. According to chromatographic analysis, only eight samples
were classified as Scotch whisky and one sample was considered suspicious. Based on the
UV-Vis analysis, seven samples were classified as Scotch whisky (agreement with GC
analysis), one as falsified (disagreement with GC), and one sample as suspicious (different
sample than the one pointed to by GC) 49. Ashok et al. and Backhaus et al. undertook the task
of assessing whether near-infrared spectroscopy (NIRS) is suitable for analyzing Scotch
whisky 50, 51. Different brands of Scottish whisky were analyzed with regard to taste, age and
barrels in which they had been aged. The data obtained were processed by PCA and PLS
regression. The spectroscopic spectrum of whisky mainly represents ethanol due to the high
content of this compound in the sample. Besides ethanol, whisky contains other alcohols,
esters, aldehydes and organic acids, called congeners. The presence of these compounds
allows the identification of the brand, age and quality of a given sample. However, it is only
possible based on the comparative analysis of fluorescence background of the spectra. This
technique combined with chemometric analysis enables the fast evaluation of whisky quality.
The samples differing with regard to brand, age and barrel type can be properly grouped by
using NIRS and PCA 50. The falsified Scotch whisky was also detected by employing mid-
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infrared spectrometry. A total of 17 samples analyzed which included falsified and genuine
Scotch whisky. The study concerned the ethanol concentration and colorants used. The
obtained data were statistically analyzed by PCA and PLS regression. Seven samples were
classified as falsified because their ethanol content was below the required standard value of
40%. One sample was on the borderline of statistical significance therefore it had been
temporarily classified as genuine. The next stage of the study dealt with testing for the
presence of commercially available colorants among which only one is authorized. Based on
the obtained results, eight samples were classified as genuine Scotch whisky, while the rest of
the samples were recognized as falsified. A comparative analysis of both data sets
demonstrated that only seven samples fulfilled both requirements and thus could be
considered genuine Scotch whisky 52. As previously mentioned, only whisky produced in
Scotland can be called Scotch whisky. Meier-Augenstein et al. 53 undertook the task of
evaluating the applicability of High Temperature Conversion-Isotope Ratio Mass
Spectrometry (TC/EA-IRMS) technique for determining the origin of whisky. To that end,
the samples of water used in the whisky production and genuine whisky from all Scottish
distilleries as well as samples of falsified Scotch, the latter supplied by the Scottish Whisky
Research Institute (SWRI), were analyzed. TC/EA-IRMS allowed for distinguishing between
the falsified and genuine whisky which suggests that the applied analytical technique can be
used for confirming the authenticity of geographical origin in whisky samples 53. Garcia et al.
54 analyzed 80 samples of whisky, namely, 50 samples of authentic brands of Scottish whisky
and 30 samples of falsified Scotch by using Fourier transform ion cyclotron resonance mass
spectrometry (FT-ICR MS). The obtained data were statistically analyzed by the PCA
method. At first, a comparative analysis of authentic whisky brands was performed to
determine whether it is possible to distinguish among them. Two brands, i.e. Buchanan’s and
J&B were found to be easily identifiable. Red Label, Black Label and White Horse were
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located closely together and even slightly overlapping in the graph which can cause problems
with a very precise identification of these brands. The second part of the analysis, described
in the same article, dealt with distinguishing between the authentic and falsified whisky
samples. The application of the FT-ICR MS technique and the PCA method demonstrated
that all authentic whiskies were grouped together in the graph, while the falsified whiskies
were farther away from them. These findings prove that the applied technique is also suitable
for the authentication of Scottish whisky 54. Yet another method capillary electrophoresis was
evaluated as a possible technique for the authentication of Scottish whisky; LC-MS/MS was
employed as a comparative technique in this study. A total of 32 samples was analyzed which
included 10 reference samples, 21 samples of possibly falsified spirits, and one sample of
whisky purchased in the local supermarket. The samples were of different vintage. The
contents of syringaldehyde, vanillin, sinapaldehyde and coniferaldehyde were determined.
For all samples classified as falsified, syringaldehyde, sinapaldehyde and coniferaldehyde
were present at concentrations below the detection limit, while vanillin concentration was
lower than in the samples of authentic whisky 55. The samples of genuine Scottish (11
samples) and American (2 samples) whisky were compared to the falsified Brazilian whisky
(2 samples) by means of electrospray ionization mass spectrometry (EI-MS). The obtained
data were analyzed by discriminant partial least square (D-PLS) regression. The analysis
demonstrated that the used technique allowed for distinguishing among Sottish, American
and Brazilian whiskies. However, a distinction between Scotch blended whisky and Scotch
single malt whisky was questionable 56.
SUMMARY
Whisky, being one of the most popular alcoholic beverages, is researched very often. Such
investigations are conducted as a result of high diversity and widespread production of this
spirit. Scotch whisky is widely appreciated by consumers. Due to this popularity, Scotch is
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the most frequently sold and analyzed whisky type. The aim of the conducted investigations
is to determine the chemical composition of this alcoholic beverage. Besides gaining
knowledge, such research allows for comparing whisky with other popular spirits. This, in
turn, allows determining the specific qualities of whisky for which it is preferentially chosen
by consumers. Due to significant diversity of brands, resulting from the type and quality of
raw materials, production location and production type, scientists often compare certain types
of whisky. The conducted studies also aim at relative quality comparisons and the
determination of features that are characteristic for a given product. Moreover, whisky is
analyzed in order to authenticate it. Because many whisky brands of different quality are
present on the market the occurrence of falsified products, made from substandard raw
materials or by cheaper methods, is frequent. Another issue is aging of whisky. Older whisky
has its own distinctly different taste which translates into different, usually higher price.
Therefore the confirmation of whisky age is of utmost importance. Among the whisky types,
Scotch whisky is falsified most often. Different types of gas chromatography are
preferentially employed to analyze whisky. The more advanced analysis is conducted by
means of two-dimensional gas chromatography, while one-dimensional gas chromatography
is used in the other analysis types. Mass spectrometry, FID and AED are mostly chosen as
detectors. The sample preparation is usually performed by using SPME technique, with
different commercially available fibers. The obtained data are statistically processed by PCA,
PLS regression, ANOVA and DFA methods. Besides chromatographic analysis, other
techniques are also used such as, liquid chromatography, spectroscopy, electronic nose, and
spectrometry. The presently applied methods allowed a relatively good determination of
whisky composition as well as distinguishing whisky from other spirits and falsified whisky.
Thanks to the development of analytical techniques, the acquisition of other interesting
information about spirit-based beverages has become possible. Despite the fact that whisky
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types have been so far researched in detail, the development of chromatographic techniques
coupled with detectors may allow for even more detailed determination of whisky
composition, while the application of analytical devices such as the electronic nose and the
electronic tongue will enable rapid identification of these spirits. Information about markers
characteristic for raw materials and geographic localities of produced whisky are still lacking.
Based on the information reviewed in this paper, the methods described above have proved to
be suitable for analyzing whisky. However, there are still undiscovered areas related to spirit-
based beverages which, when properly researched, would improve the quality of the
produced goods.
Table 1. Examples of analysis of whisky
"Acknowledgments
The authors acknowledge the financial support for this study by the Grant No.
2012/05/B/ST4/01984 from National Science Centre of Poland."
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Table 1. Examples of analysis of whisky
Sample Object of study Apparatus Lit.
American bourbon detection of 23 active aroma substances HRGC-O 9
American bourbon quantitative analysis of 31 compounds TD-HRGC-MS 10
Malt whisky identify green note compounds in malt whisky MDGC-MS-O 11
Scotch and Irish
whisky
quantitative analysis of the selected compounds GC-MS, SPME 6
Scotch whisky analysis of ethyl esters GC-GC-MS, SPE 12
Whisky bought in
local market in
Spain
monitoring the contents of 12 selected haloanizoles SPME-GC-AED 14
Whisky from 9
countries
analysis of phenols GC-MS 15
Malt whisky from
Scotland
analysis of γ-decalaktone and γ-dodecalactone GC-MS, GC-O 16
whisky analysis of ethyl carbamate GC/MS-MS 17
Scotch whisky analysis of ethyl carbamate GC-MS 18
whisky analysis of methanol e-nose 19
whisky analysis of zinc, lead and copper ions ASV, AAS 25
whisky comparison of cachaça, whisky, rum, vodka, gin, GCxGC-TOFMS 26
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tequila and selected liqueurs
Scotch whisky comparison of whisky and cognac GC-MS 29
whisky distinguishing the types of alcoholic beverages e-nose 27
Whisky from
Canada, Finland,
Ireland, Scotland
distinguish among the whisky samples with regard
to the country of their origin
GC-FID, UV-Vis 30
Scotch and Irish
whisky and bourbon
distinguish among Scotch and Irish whisky and
bourbon
GC-MS 31,
34
blended and malt
whisky, bourbon,
Canadian and
Danish whisky
comparison of whisky and brandy GC-FID 40
Scotch whisky distinguishing among various whisky types, i.e.
blended from single malt
optical
spectroscopy
37
Scotch whisky distinguish among Scottish whiskies of different
quality
sensory
evaluation
42
Scotch whisky distinguishing among blended whiskies of different
quality
SPME-HRGC-
MS
45
Black Label,
Ballantine's and
West Highlands
distinguish among specific whisky brands GC-MS, SPME 41
Scotch whisky samples differing with regard to brand, age and
barrel type
NIRS 50
Blended, malt and
grain whisky
determine the region of sample origin and sample
type
AAS 39
Scotch whisky distinguishing among the analyzed samples, and
finding the samples of falsified spirits
GC-C-IRMS 46
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Scotch whisky authentication of Scottish whisky GC-MS 47,
48
Scotch whisky authentication of Scottish whisky UV-Vis 49
Scotch whisky detection of falsified scotch whisky mid-infrared
spectrometry
52
Scotch whisky determining the origin of whisky TC/EA-IRMS 53
Scotch whisky authentication of Scottish whisky FT-ICR MS 54
Scotch whisky authentication of Scottish whisky Capillary
electrophoresis
55
Scotch, American
and falsified
Brazilian whisky
distinguishing among Sottish, American and
Brazilian whiskies.
EI-MS 56
... Aiming at the best for consumers, methodologies to control the production process and the final quality of beverages may cover different techniques and instrumentation. Methods for analyzing honey (Arvanitoyannis et al. 2005), milk (Souza et al. 2011;Macedo Dos Santos and Pereira-Filho 2013;Santos et al. 2013), juices (Ehling and Cole 2011;Obón et al. 2011), teas (Budínová et al. 1998;Deng and Yang 2013), wines (Bevin et al. 2006;Egorov et al. 2017;Ferreira et al. 2020), beers (Lachenmeier 2007), spirits (Nordon et al. 2005;Lachenmeier et al. 2008;Garcia et al. 2013;Wiśniewska et al. 2015) and other distilled beverages (Santos et al. 2019) are often reported in the literature aiming to determine analyte concentration or physicochemical properties. ...
... Among alcoholic beverages, it is well-known that whisky is the most often adulterated due to its worldwide popularity. Whisky is a distilled beverage from malted grains that are aged in wooden barrels (Wiśniewska et al. 2015). Due to their broad trade and consumption, whiskies are common hotspots of adulteration of different types (Hardy 1992;MacKenzie and Aylott 2004), such as simple dilution with cheaper alcoholic drink or water (Rezende et al. 2016). ...
Article
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Adulteration of alcoholic beverages is a worldwide concern for authorities, mainly due to risks to human health. This report describes the use of portable analytical platforms combined with chemometrics to trace the authenticity profile of whisky. Rapid analysis by miniaturized methodologies based on separation and colorimetric reactions as well as pH and conductivity measurements is proposed as a strategy for forensic screening at the point of need. Anionic profiles of whisky were obtained using a microchip electrophoresis system with integrated contactless conductivity detection. The indirect detection of caramel and the determination of alcohol content were performed by colorimetric reactions on paper-based analytical devices, which were explored in single microzones and foldable devices, respectively. These methodologies were successfully applied to a total of 50 whisky samples, 45 of which were adulterated and 5 authentic. A correlation study involving these markers and their analytical response through different techniques was then performed. A chemometric tool employing all these parameters was able to distinguish more than 90% of adulterated samples from authentic ones, demonstrating that the proposed methodology is effective for mapping whisky samples. These portable methods have great potential for use at the site of apprehension, due to the low consumption of samples and speed of analysis.
... In general, the samples subjected to longer ageing times present the highest concentrations of these compounds (Bortoletto & Alcarde, 2013;Canas, 2017). All the same, the relationship between ageing time and phenolic compound content is not a simple one (Wiśniewska et al., 2015). The content of these biomolecules in the nal product is affected by several factors, like the wood's region of origin, age and species as well as the heat treatment applied to the wooden barrel production. ...
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The ageing of alcoholic beverages is a common practice in order to increase their quality due to the release of wood extractable compounds from the barrels used. However, this process is slow and can take several years. This research focussed on optimising the use of Quercus alba chips and ultrasound in the accelerated ageing process of sugar cane spirit using the response surface methodology. The effect of temperature and ultrasound was analysed using a two-level factorial design type 2 ² . Subsequently, the accelerated ageing process was optimised using response surface methodology. Temperature and time of exposure to ultrasound energy were the selected independent variables. As a response variable, the total polyphenol index (TPI) was selected. In addition, the CIELab method was used to determine the colour characteristics (L*, a*, b*) of the aged samples. Roasting had a negative effect on the TPI, while the oak chips that were untoasted and treated with ultrasound obtained the highest TPI yield (80.5–81.5 mg GAEeq/L). The TPI values obtained through the use of the accelerated ageing method suggest that it is more efficient than the traditional ageing process, as it leads to a decrease in the maturation period of sugar cane spirit. Regarding the colour properties, a higher intensity of colour was found in the samples where the accelerated ageing method was applied. The temperature and sonication time of 48.9°C and 18.8 min were the optimal parameters to obtain a TPI value (85 GAE eq ./L) comparable to the Brandy Solera Reserve (12–18 months for the traditional method) for sugar cane spirit using the accelerated method. The findings of this research can contribute towards the development of new ageing processes of distillates, mainly in terms of decreasing ageing times.
... Literature reports clearly suggest that numerous cases of food adulteration have been reported, including the use of substances that pose a threat to the health and life of consumers. Examples of such activities can be given as follows: mixing melamine and wheat gluten to increase the protein content [2], determine aroma profiles, which can then be used to define the quality and authenticity of the tested whisky [56]. Especially the analysis of esters, which have the greatest impact on the aroma of the alcohol, enables an assessment of the aging process and, as a result, the verification of the authenticity of the age of whisky [57,58]. ...
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Citation: Gajek, M.; Pawlaczyk, A.; Maćkiewicz, E.; Albińska, J.; Wysocki, P.; Jóźwik, K.; Szynkowska-Jóźwik, M.I. Assessment of the Authenticity of Whisky Samples Based on the Multi-Elemental and Multivariate Analysis. Foods 2022, 11, 2810.
... A possible explanation for HP1810 (18 years), HP1210 (12 years), and FG12 (12 years) presenting the highest total concentration of volatile composition can be correlated with the aging of these whiskeys. It is well-documented that the ageing process of beverages in oak casks contributes to the enrichment of the volatile fingerprint, since several phenomena occur such as the extraction of wood components, the evaporation of beverage VOCs, the oxidation of compounds in the beverage, and the reaction between the wood and beverage components [34][35][36][37][38][39]. Regarding the distribution of the chemical families, alcohols (on average 45.6% of total volatilomic fingerprint), esters (30.6%), and acids (18.5%) were the predominant chemical families identified in the whiskeys investigated (Figure 4b). ...
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The volatilomic fingerprint of nine different whiskeys was established using a rapid and sensitive analytical approach based on dispersive liquid–liquid microextraction (DLLμE) followed by gas chromatography mass spectrometry detection (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The influence of the extractor solvent on the extraction efficiency of volatile compounds (VOCs) was evaluated by DLLμE/GC-MS. The highest amounts of VOCs were obtained using 5 mL of sample, dichloromethane as the extractor solvent, and acetone as the disperser solvent. The proposed method showed no matrix effect, good linearity (R2 ≥ 0.993) in the assessed concentration range, recovery (ranging from 70 to 99%, precision (RSD ≤ 15%) and sensitivity (low limits of detection and quantification). A total of 37 VOCs belonging to different biosynthetic pathways including alcohols, esters, acids, carbonyl compounds, furanic compounds and volatile phenols were identified and quantified using DLLμE/GC-MS and DLLμE/GC-FID, respectively. Alcohols (3-methylbutan-1-ol, propan-1-ol), esters (ethyl decanoate, ethyl octanoate, ethyl hexanoate), and acids (decanoic acid, octanoic acid, hexanoic acid) were the most abundant chemical families. The multivariate statistical analysis allowed for the discrimination of whiskeys based on their volatilomic fingerprint, namely octanoic acid, 2-furfural, ethyl octanoate, ethyl hexanoate, acetic acid, ethyl dodecanoate, butan-1-ol, and ethyl decanoate.
... It finds application in the analysis of VOCs present in alcoholic beverages [22], but there are no reports of analytical methods involving the application of GC-BID for the analysis of these compounds for our types of samples. In addition, the BID (Nondestructive detector) can be coupled to existing chromatographic and spectroscopic techniques, which have been used for analyses of authenticity and certification of whisky origin, through different statistical and chemometric analyses [23]. ...
Article
To maintain quality control in the production of distilled beverages, it is necessary to perform several types of chromatographic analysis, where gas chromatography (GC) coupled with mass spectrometry (GC/MS) and flame ionization detector (GC-FID) have been used as traditional analysis techniques for volatile organic compounds. More recently the dielectric barrier discharge ionization detector (BID) has been coupled to GC (GC-BID) which is more sensitive than the FID and the thermal conductivity detector (TCD) for analyzing various volatile compounds. This study aims to develop a new method for determining higher alcohols, n-butanol, and ethyl acetate in cachaça and whisky samples using headspace solid-phase microextraction (HS-SPME) followed by GC-BID. The HS-SPME method was optimization with multivariate analysis. The analytical results were provided by the weighted linear Square (WLS) method for linearity correction, internal standard addition (ISA) as a calibration method for matrix effect correction, reproducibility, recovery and accuracy. The best conditions for extraction of the compounds by HS-SPME were obtained for 50 • C, 20 min and without addition of NaCl. The WLS regression allowed to obtaining satisfactory correlation coefficients (0.9632 to 0.9992). The matrix effect (ME) was verified for n-propanol, isobutanol and isoamyl in both matrices. The recovery values of the cachaça matrix ranged from 81.24 to 106.94 %, except for isoamyl alcohol, and ranged from 82.06 to 106.25 % for the whisky matrix, except for n-butane. The precision ranged from 0.66 to 7.38 % and 0.62 to 6.77 % for the cachaça and whisky samples, respectively. Limit of detection (LOD) values ranged from 0.26 to 0.51 mg L-1 , while limit of quantification (LOQ) values ranged from 0.78 to 1.55 mg L-1. The validation process and statistical methods were successfully applied to quality assurance of the analysis of cachaça and whiskey samples, where n-propanol, ethyl acetate, isobutanol and isoamyl were detected for all samples within the maximum content for higher alcohols and ethyl acetate, except n-butanol. The method can be satisfactorily applied to quantify higher alcohols and esters in samples of alcoholic beverages.
... Com os resultados apresentados, pode-se inferir que, a despeito de interações moleculares que se seguem à extração -e que são indispensáveis para caracterizar o envelhecimento -as proporções relativas entre os componentes fenólicos analisados, conforme extraídos da madeira, permanecem representativas de sua identidade vegetal, independente do tempo total de armazenamento. Assim, corroborando trabalhos prévios (WIŚNIEWSKA et al., 2014, MAIA et al., 2020 os resultados apontam a viabilidade de se certificar as diversas madeiras brasileiras empregadas no envelhecimento de cachaças. ...
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O armazenamento em recipientes de madeira integra o processo de produção de bebidas destiladas, caracterizando a etapa de maturação ou envelhecimento. A cachaça – legalmente definida como bebida destilada da cana-de-açúcar produzida em território brasileiro - é armazenada em barris de diversas madeiras nativas, assim como em barris de carvalho europeu e americano (Quercus). Dada a diversidade de madeiras empregadas, é importante dispor de parâmetros químicos que permitam atestar a identidade de cada madeira, cujos componentes extraídos são reconhecidamente bioativos. No entanto, a legislação brasileira define o envelhecimento tão somente mediante parâmetros físicos afetos à geometria dos recipientes e ao tempo de armazenamento. Nesse trabalho, analisando uísques e cachaças envelhecidas em carvalho, demonstra-se que, a despeito da diversidade de origens, a identidade do carvalho fica bem caracterizada nos perfis cromatográficos, com predominância consistente dos ácidos elágico e gálico e do siringaldeído. Conclui-se que é possível atestar o emprego do carvalho no envelhecimento de bebidas destiladas, independente da diversidade de tratamentos a que a madeira possa ter sido submetida. E aponta-se a possibilidade/relevância de se estender a metodologia (HPLC-UV) para fins de caracterização das madeiras brasileiras nativas empregadas no envelhecimento da cachaça. Trata-se de um avanço importante para fins de certificação da identidade da cachaça e valorização da flora nativa brasileira.
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The market value of distilled beverage relies on its quality with a major contribution of distinctive and fascinating aromas. The aroma of distilled beverage is built on the basis of chemical components and can be modified through a series of physical and chemical processes such as aging. Revealing the hidden knowledge behind the evolution of numerous chemical components during these physicochemical processes in distilled beverages is not only significant but also challenging due to its complex system. In this review, the trends in the changes of associated aroma compounds over aging are proposed on the basis of understanding the relationship between chemical components and aroma profiles of numerous typical distilled beverages. The different aging systems, both classical platforms from Eastern countries (pottery jars) to Western countries (wood barrels), and modern platforms such as artificial aging technologies are outlined and compared with their respective applications. Optimizing aging processes is a challenging but imperative step, which warrants further fundamental knowledge from targeting aging-related molecules to the exploration of multitude physicochemical reaction mechanisms that occur during this process, such as the formation of potent odorant compounds in specific containers and environments, as well as mass transfer processes between solid and liquid interfaces. Understanding these maturation mechanisms of distilled beverages expressed by chemosensory signature holds promise for major improvements in future aging technologies that can efficiently yield stable and high-quality products.
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The study of consumer attitudes is particularly important for products related to tradition. Pálinka is Hungary's national beverage; the homemade distillate is primarily legally different from pálinka and it cannot be marketed. The main goal of the research is to analyse the role of the three attitude components (cognitive, affective and conative), consumer ethnocentrism and drinking motives in shaping the consumer attitude towards the Hungarian pálinka and the homemade distillate and a popular, but not Hungarian beverage, whisky. Data were collected by questionnaires using a quota sampling method, resulting in a sample of 626 respondents. In this paper we demonstrate the importance of the affective component using structural equation modelling, and the way consumer ethnocentrism influences the favorable consumer attitude to homemade distillate through emotions. The study has revealed the opposite effect of consumer ethnocentrism in the case of whisky, and the lack of effect in the case of pálinka. The social alcohol drinking motivation also shapes the favorable consumer attitudes towards the homemade distillate and whisky. The consumer preference is also supported by using the Multiattribute Attitude Model and the conjoint-analysis. The scientific value of the study lies in using different methods for understanding the factors that can shape the consumer attitude towards national beverages. Improving the consumer attitude towards pálinka requires a comprehensive marketing strategy covering all three attitudinal components, and from a consumer ethnocentrism perspective, the positioning of pálinka as a national drink needs to be strengthened by the producers. The study has ignored the role of brand, tradition, packaging and nostalgia. Future research can examine the role of these factors in consumer attitude towards national alcoholic beverages. By inserting the conceptual model of this study into the Theory of Planned Behaviour model, the effects of the subjective norms and perceived behavioral control can also be analysed.
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A total of 170 samples of whisky from 11 countries were analysed in terms of their elemental profiles. The levels of 31 elements were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS): Ag, Al, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Sn, Sr, Te, Tl, U, and V, Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) Ca, Fe, K, Mg, P, S, Ti, and Zn and Cold Vapor-Atomic Absorption (CV-AAS): Hg techniques in those alcoholic samples. A comparative analysis of elemental profiles was made on the basis of the content of chosen elements with regard to selected parameters: country of origin, type of whisky (single malt and blended) and age of products. One of the elements which clearly distinguishes single malt and blended types of whisky is copper. Single malt Scotch whisky had a uniform concentration of copper, which is significantly higher for all malt whisky samples when compared with the blended type. Analysis of samples from the USA (n = 26) and Ireland (n = 15) clearly revealed that the objects represented by the same product but originating from independent bottles (e.g., JB, JDG, BUS brands) show common elemental profiles. On the other hand, comparative analysis of Scotch whisky with respect to aging time revealed that the longer the alcohol was aged, (i.e., the longer it stayed in the barrel), the higher the content of Cu and Mn that was recorded.
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The paper presents a new approach to the computer aided diagnostic systems for the needs of quantitative EMG. The approach is based on the analysis of wavelet scalograms of the motor unit action potentials calculated on the basis of Symlet 4. The scalograms provide the vector consisting of 6 features describing the state of a muscle that can be reduced to 2 with use of Linear Discriminant Analysis. In consequence, the healthy, miogenic and neurogenic cases can be successfully classified with use of the linear methods.
Chapter
Scotch whisky is the best-selling spirit drink in the world, with Scotch, North American, and other whiskies taking 17 %, 12 %, and 6 %, respectively, of the market in 1993 ([International Drinks Bulletin, 1994]). Whiskies are distilled alcoholic beverages, prepared from cereals fermented with yeast and normally matured in oak barrels. There are many possible ways of producing whiskies, within the limitations set by the materials and processes available, and details vary depending on custom and regulation in producing countries. The products now available are those that have evolved under local circumstances, and subsequently have been stabilized by legislation. The European Union (EU) definition of whisky ([EEC, 1989]) is fairly broad, and defines the starting material (any cereals), starch degrading enzymes, fermentation, distillation at > 94.8 % v/v (so that the flavor is derived from the materials used), maturation in wooden casks of less than 700 1 for at least 3 years, and offered for sale at a minimum 40 %v/v.
Chapter
Spirit drinks are food products and represent a major outlet for the agricultural industry all over the world. This outlet is largely the result of the flavour quality and reputation these products have acquired on the world market over hundreds of years; various national and international legal decrees, standards, and specifications lay down rules on the definition, description, and presentation of the different categories of spirit drinks [1-4] which can be separated in two main categories, distilled spirits and liqueurs. Distilled spirits have alcoholic strengths between 30 and 50% v/v and are produced by distillation from fermented agricultural products containing carbohydrates; their flavour is not only characterised by aroma compounds originating from the raw material and the alcoholic fermentation, but also from distillation, storage, and ageing. Liqueurs are spirits with a minimum ethanol content of 15% v/v and a sugar content of 100 g L-1; they are produced by flavouring ethanol of agricultural origin, distillates of agricultural origin, or one or more spirit drinks with natural plant materials such as herbs, fruits, fruit juice, cream, chocolate, steam-distilled essential oils, distilled spirit drinks, or natural or artificial flavouring extracts.
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The fatty and sweet flavours in malt whisky were studied by GC-olfactometry and GC-mass spectrometry. These compounds were identified as β-methyl-γ-octalactones, γ-nonalactone, γ-decalactone and γ-dodecalactone. Although β-methyl-γ-octalactones were present in matured malt whiskies and considerable amounts of γ-nonalactone were present in all, the content of γ-decalactone and that of γ-dodecalactone varied in both matured and non-matured malt whiskies. A high correlation was observed between the scores of descriptive analysis and the γ-decalactone and γ-dodecalactone content. The malt whiskies containing certain amounts of both γ-decalactone and γ-dodecalactone had sweet and fatty flavours, and thus it is evident that these lactones contribute to the quality. Both of these lactones are thought to be important for the flavour of malt whisky.
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Trace element analyses were conducted on 35 Scotch Whiskies to investigate if the trace element fingerprint is characteristic for different kinds of Scotch Whiskies. The element concentrations of the eight elements investigated varied considerably; for zinc and iron three orders of magnitude (0.02 to 20 mg Zn L−1 and 0.02 to 28 mg Fe L−1), while nickel and magnesium varied within two orders of magnitude (0.002 to 0.6 mg Ni L−1 and 0.02 to 4 mg Mg L−1). Small variations were detected for calcium, sodium and copper (0.5 to 4 mg Ca L−1, 2 to 24 mg Na L−1, 0.1 to 1.7 mg Cu L−1), while lead, with one exception was usually below 0.005 mg L−1. Using Cluster analysis no characteristic metal fingerprints were identified for the different geographical regions. However, when a second set of samples (42 malt and 8 blend whiskies) were analysed for copper, the copper concentration could be used as a criterion to distinguish Blended or Grain Scotch from Malt Whisky. The Malt Whiskies had a copper concentration between 385 and 480 ng mL−1 (95% confidence limit) while the copper concentration of the blended whiskies was between 143 and 242 ng L−1. Since the difference was highly significant (p < 0.0001), it is suggested that a simple copper analysis could be used as one test to distinguish between a Blended and Malt Scotch Whisky.
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Gas chromatographic methods are described for the determination of naturally occurring ethyl carbamate in distilled spirits at levels as low as 5 ppb. Bottled products, such as whisky, gin and brandy, are extracted in the presence of n-propyl carbamate as internal standard and analysed by capillary column gas chromatography with either nitrogen specific or mass spectrometric detection. A shorter extraction procedure is satisfactory when the more sensitive and selective mass spectrometric detection is used. Direct sample injection without extraction may be used for higher alcoholic strength cask and new-make samples. Analysis of 181 blended Scotch whisky samples indicated ethyl carbamate concentrations ranging from 20 to 75 ppb. Concentrations in 48 malt whiskies ranged from 15–100 ppb. Ethyl carbamate was not detected in gin, vodka and rectified neutral alcohol. All concentrations in bottled product fell below the Canadian limit of 150 ppb in distilled spirits.
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