Malt Whiskies Research Articles

Comparative analysis of the aromatic profile of single malt whiskies from different regions of Scotland using GC-MS, GC-O-MS and sensory evaluation

Single malt whiskies are popular around the world. The 37 esters, 10 alcohols, 10 phenols, 8 aldehydes, 8 acids, 6 alkanes, 4 ketones and 3 heterocycles were detected in the single malt whiskies extracted from different origins in Scotland by HS-SPME (headspace solid-phase microextraction) and LLE (liquid-liquid extraction) and identified by GC-MS (gas chromatography-mass spectrometry). QDA (quantitative descriptive analysis) combined with multivariate statistics were used to investigate the effects of the differential aroma-active compounds on the sensory aroma characteristics. O-cresol, ethyl 2-methylbutyrate, 5-methylfurfural and propionic acid might influence the flavor of single malt whiskies of different origins in Scotland. The 54 key whisky aroma compounds were analyzed, with isoamyl acetate having the highest OAV (odour activity value) of all whisky samples. In addition, the aromas of volatile compounds were analyzed using OSME (odor-specific magnitude estimation) and OAV. Based on these facts, the researchers developed a flavour wheel with 10 aroma profiles. This paper evaluates Scotch single malt whisky from a Chinese perspective, which helps the development of the Chinese whisky market.

Do geographical appellations provide useful quality signals? The case of Scotch single malt whiskies

Do geographical appellations provide useful quality signals? The case of Scotch single malt whiskies

Using Carbon Isotopes to Fight the Rise in Fraudulent Whisky

ABSTRACTA major threat to the Scotch whisky industry is the sale of counterfeit single malt whiskies with purported distillation years in the 19th and early- to mid-20th centuries. However, these are often much more recent spirits, distilled in the latter part of the 20th or first part of the 21st centuries. These sales impinge upon the reputation of auction houses, retailers, brand owners and distillers. The atmospheric testing of nuclear weapons in the 1950s and early 1960s has enabled a precise calibration curve to be created, however, there are several reasons why this may not be appropriate for establishing the year of whisky distillation. We have created a 14C calibration curve derived from known-age, single malt whiskies for the period 1950–2015 that enables whisky distilled during the period from 1955 onwards to have the distillation year determined to within 1–3 years for certain periods. However, because of the shape of the curve, two possible age ranges are often possible. The correct range can often be determined from a further plot of δ13C values against distillation year, which shows a trend of decreasing values through time. Several examples are given of the determination of both genuine and fake products.

Should You Invest in an Old Bottle of Whisky or in a Bottle of Old Whisky? A Hedonic Analysis of Vintage Single Malt Scotch Whisky Prices

AbstractThis article examines the main determinants of differences in ask prices set by investors for single malt whiskies from Islay in Scotland using an original dataset collected from a web trading platform specializing in whisky investment. We find strong evidence that the vintage age (the number of years between the distillation date and the data collection date) positively affects investor asking prices. More precisely, given that the characteristics of whisky, unlike wine, do not change over time once bottled, we disentangle the vintage age effect by subdividing the vintage age into whisky age (the time spent in the cask) and bottle age (the time spent in the bottle). Our results show that whisky age has a more pronounced impact (8.9% per year on average) than bottle age (6.7%). Other findings include the significant influence of distillery reputation, with a moderating effect for independent bottling (i.e., not in-house by the distiller itself) and a positive impact for cask strength whiskies compared to diluted ones. (JEL Classifications: G11, L15, Q11)

A novel approach to assess the quality and authenticity of Scotch Whisky based on gas chromatography coupled to high resolution mass spectrometry

Whisky is one of the most popular spirit drinks in the world. Unfortunately, this highly valued commodity is vulnerable to fraud. To detect fraudulent practices and document quality parameters, a number of laboratory tests based on various principles including chromatography and spectroscopy have been developed. In most cases, the analytical methods are based on targeted screening strategies. Non-targeted screening (metabolomics fingerprinting) of (semi)volatile substances was used in our study. Following the pre-concentration of these compounds, either by solid phase microextraction (SPME) or by ethyl acetate extraction, gas chromatography (GC) coupled to tandem mass spectrometry (Q-TOF mass analyser) was employed. Unsupervised principal component analysis (PCA) and supervised partial least squares discriminant analysis (PLS–DA) were used for evaluation of data obtained by analysis of a unique set of 171 authentic whisky samples provided by the Scotch Whisky Research Institute. Very good separation of malt whiskies according to the type of cask in which they were matured (bourbon versus bourbon and wine) was achieved, and significant ´markers' for bourbon and wine cask maturation, such as N-(3-methylbutyl) acetamide and 5-oxooxolane-2-carboxylic acid, were identified. Subsequently, the unique sample set was used to construct a statistical model for distinguishing malt and blended whiskies. In the final phase, 20 fake samples were analysed and the data processed in the same way. Some differences could be observed in the (semi)volatile profiles of authentic and fake samples. Employing the statistical model developed by PLS-DA for this purpose, marker compounds that positively distinguish fake samples were identified.

A gradient of mercury concentrations in Scottish single malt whiskies.

Mercury (Hg) concentrations were measured in 26 Scottish single malt whiskies, and all found to be very low (<10ngL(-1)), posing no threat to human health through reasonable levels of consumption. However, a significant south-to-north declining gradient in Hg concentrations was observed reflecting that reported for atmospheric deposition. We speculate that this gradient could be due to a combination of contemporary deposition and the legacy of industrial mercury emissions and deposition over the last 200years affecting concentrations in local waters used in whisky production. As UK atmospheric emissions of mercury have declined by 90% since the 1970s, we suggest that whisky being produced today should have even lower Hg concentrations when consumed in 10- to 15-years time. This reduction may be compromised by the remobilisation of contaminants stored in catchment soils being transferred to source waters, but is very unlikely to raise the negligible health risk due to Hg from Scottish single malt whisky consumption.

Quantification of Bromophenols in Islay Whiskies

Two single malt whiskies from the Scottish island Islay, i.e., Laphroiag and Lagavulin, are characterized by an iodine-like flavor associated with marine environments. In this study we investigated if this flavor impression could be due to bromophenols which are character impact compounds of marine fish and shrimps. In this study we developed a method suited for the determination of dibromo- and tribromophenols in whisky. Aliquots were O-acetylated, and quantification was carried out with gas chromatography with electron-capture negative ion mass spectrometry (GC/ECNI-MS). Both Islay whiskies contained more than 400 ng/L bromophenols with 2,6-dibromophenol being the most relevant homologue (>300 ng/L, respectively). These concentrations are at least 1 order of magnitude higher than the taste threshold of 2,6-dibromophenol in water. A third Islay whisky, Bowmore, contained ∼100 ng/L bromophenols while seventeen other whiskies from other regions in Scotland as well as from the USA, Ireland, and Germany contained at least 1 order of magnitude less than the two whiskies with the marine taste. Accordingly, bromophenols may contribute to the marine flavor and taste of Laphroaig and Lagavulin.

Inhibition of recombinant GluN1/GluN2A and GluN1/GluN2B N-methyl-D-aspartate receptors by single malt whiskies

NMDARs (N-methyl-D-aspartate receptors) are considered to be a target for the inhibitory actions of ethanol. While profound inhibition of both native and recombinant NMDARs can be observed following the application of high concentrations of ethanol the levels of inhibition seen with lower concentrations of ethanol are more modest. Here, we report the effects of inhibiting NMDAR-mediated responses with ethanol concentrations that are experienced during the social consumption of alcohol comparing levels of inhibition seen with 'pure' ethanol with those produced by ethanol contained in three popular single malt whiskies.

Maturation of Whisky Changes Ethanol Elimination Kinetics and Neural Effects by Increasing Nonvolatile Congeners

The maturation of distilled spirits is known to change constituent congeners to improve the qualities of smell and taste. However, it has been largely unknown how maturation modifies the pharmacokinetics or neuropharmacological effects of ethanol. We used single malt whiskies to investigate the effects of spirit maturation on ethanol metabolism and drunkenness. Mice were injected with 5-year (5-y) or 20-year (20-y) aged single malt whisky with a concentration of 20% (w/v) ethanol at a dose of 3 g/kg. The concentrations of ethanol and its metabolites in the blood and the duration of loss of righting reflex (LORR) were compared between the 2 whisky groups. In addition, the effects of nonvolatile congeners in whisky on the biomedical reactivities of ethanol were investigated by administering a nonvolatile fraction added to a 20% ethanol solution, whose fraction was prepared by evaporating 16-y whisky. Liver alcohol dehydrogenase (ADH) activity was measured with whisky as the substrate or in the presence of nonvolatile congeners with ethanol as the substrate. The rate of ethanol elimination (mmol/kg/h) was smaller in the 20-y whisky group than in the 5-y group (p<0.01 by Fisher's protected least significant difference), which resulted in lower concentrations of blood acetaldehyde and acetate in the former group than in the latter group (p<0.01 by ANOVA). Nonvolatile congeners added to the ethanol solution also depressed the rate of ethanol elimination in mice. In vitro studies demonstrated that liver ADH activity measured with whisky as the substrate was decreased as a function of the age of the whisky, and that the activity measured with ethanol as the substrate was strongly inhibited by nonvolatile congeners. The duration of LORR was longer in the 20-y group than in the 5-y group (p<0.01). Nonvolatile congeners also prolonged the duration of ethanol-induced LORR, when administered together with ethanol. Maturation of whisky delayed ethanol metabolism to lower the level of blood acetaldehyde and acetate with increasing inhibition of liver ADH activity by nonvolatile congeners. It also prolonged drunkenness by enhancing the neurodepressive effects of ethanol, due to increases in the amount of nonvolatile congeners. These biomedical effects of whisky maturation may reduce aversive reactions and cytotoxicity due to acetaldehyde, and may also limit overdrinking with the larger neurodepression.

貯蔵に伴う蒸留酒のマクロなクラスターサイズの変化

We defined the macroscopic cluster size of liquor in order to discuss quantitative changes in solution structure with storage. We determined the size of three kinds of clusters in malt whiskies. First, NMR spectra were measured for aqueous ethanol solutions, and the population fractions defied by eq.(3)were calculated from the changes in the proton chemical shifts with increases in ethanol concentrations. Next, IR spectra were taken for the gases evaporated from the whiskies and aqueous ethanol solutions. Comparisons between the band areas from the whisky and those from the aqueous ethanol solution made it possible to obtain the ratios of the water and of the ethanol molecules evaporated from the two solutions. Finally, the population fractions for aqueous ethanol solutions were converted into those for the whiskies by these ratios according to eq.(12), and the sizes of the three clusters were calculated for each whisky. The results differ from previous ones: specifically, as the period of storage becomes longer, the size of the water clusters increases while that of the ethanol clusters decreases and that of the water-ethanol clusters is almost constant.

Complementary therapies: relief from judgement by numbers?

T Dunning. Complementary therapies: considerations for diabetes care. Pages 118– 125 Florence Brown*, * North Glasgow Hospitals University NHS Trust, Glasgow, Scotland There can be no doubt that complementary therapies (CTs) are here to stay and shouldn't be ignored simply because of a lack of evidence base. Trisha Dunning's comprehensive overview of CTs raises some interesting points. I wonder how many health care professionals enquire about CT use and, if the patient admits use, how judgemental our reaction might be? I remember a few years ago a recently diagnosed (type 1) teenager told me proudly that his diabetes had improved since he had started taking some large blue capsules sent over from Pakistan by a concerned family who wanted to help. Conflict ensued as the consultant physician recommended that he stop the capsules but the family wanted to attribute his improved glycaemic control to their intervention. We, of course, attributed improvement to the evidence-based insulin therapy and dietary recommendations. The nature of diabetes care is that the diabetic patient is judged by numbers: weight, BMI, HbA1c, lipid levels, blood pressure etc. No matter how empowered the patient, it must feel like there are some ‘numbers’ over which there is little sense of control. The use of CTs, therefore, could be seen as an act of self-empowerment. In seeking out a CT the patient has ownership, exerts control and monitors outcomes more likely to relate to psychological and spiritual as well as physical well-being. By virtue of the choice then, it is likely that beliefs about the efficacy of the treatment are held—a powerful tool in itself. Trisha Dunning's distinction that CTs are centred on health rather than disease is cause for reflection. This highlights the dilemma that health care professionals face in attempting to facilitate the achievement of ever tighter targets with an approach that acknowledges the patient as more than a collection of organs! As a well known American ‘professor of empowerment’ said, when trying out a selection of malt whiskies: ‘More research is needed’. As CT use amongst people with diabetes increases then the requirement for more sophisticated research will surely emerge.

Obituary

Obituary

Identification of green note compounds in malt whisky using multidimensional gas chromatography

AbstractWe studied green note compounds in malt whisky using multidimensional GC–MS–olfactometry (MDGC–MS–O). Two aldehydes and three alcohols were shown to contribute to the green note: E,Z‐2,6‐nonenal and E‐2‐nonenal, and 1‐octen‐3‐ol, 4‐hepten‐1‐ol and nonan‐2‐ol, respectively. Malt whiskies with high green note scores organoleptically contained more of the aldehydes and nonan‐2‐ol than those with low scores. This is the first time that E,Z‐2,6‐nonadienal, 1‐octen‐3‐ol, and 4‐hepten‐1‐ol have been identified in malt whisky. These compounds are related to lipid oxidation and degradation, and formation may be due to the action of lipoxygenase. In addition, MDGC–MS–O was effective in examining small amounts of compounds in malt whisky, which contains many volatiles, since this method enables the volatiles in a complicated matrix to be highly resolved without the influence of large amounts of volatiles. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Investigations into the Use of Copper and Other Metals as Indicators for the Authenticity of Scotch Whiskies

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.

Stereospecificity of 10-Hydroxystearic Acid and Formation of 10-Ketostearic Acid by Lactic Acid Bacteria

We studied the variation in enantiomeric excess of 10-hydroxystearic acid (10-HSA) produced by several strains of lactic acid bacteria from oleic acid. Using 1H-nuclear magnetic resonance and chiral-phase HPLC to reveal the microorganisms involved and the mechanisms of the formation, we found that most strains produced nearly optically pure (R)-10-HSA. Among them, one strain of Lactobacillus hilgardii, isolated from a distillery in Scotland, produced 10-HSA with lower enantiomeric excess, and furthermore, the strain produced a large amount of 10-ketostearic acid along with the 10-HSA. In this strain, 10-ketostearic acid was found to be generated from 10-HSA supplied to the cells. Also, the enantiomeric excess of γ-dodecalactone, formed from 10-ketostearic acid by distiller's yeasts, was found to be within the range of −17 to 32%; these findings were consistent with the distribution of the enantiomers in malt whiskies. From these results, two conceivable pathways for the formation of lactones during the production of malt whisky were proposed: from 10-ketostearic acid with the involvement of distiller's yeast and from nondistiller's yeast with 10-HSA as an intermediate.

Estimation of the Distribution of Enantiomers of γ-Decalactone and γ-Dodecalactone in Malt Whisky

Lactic acid bacteria generate precursors of γ-lactones, which contribute to sweet and fatty flavour, from unsaturated fatty acids. In this study the distribution of enantiomers of γ-decalactone and γ-dodecalactone in malt whiskies were studied using multi-dimensional GC in an effort to elucidate the mechanism of formation of these lactones. The enantiomeric excess of these lactones was within the range of −10 to 30%. Furthermore, racemic methyl-10-hydroxystearate was synthesized and optically resolved by chiral-phase HPLC. The chirality of γ-dodecalactone produced was dependent on the chirality of the hydroxy fatty acid or its methyl ester supplied as the substrate, based on the results of a series of experiments in which the acid or the ester was supplied to distiller's yeast.

Detection or γ-Lactones in Malt Whisky

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.

Progressive increase in minimum proton exchange rate with maturation of liquor

Proton exchange rate measurement was carried out by 17O-NMR spectroscopy using mother liquors of malt (aged for 0 to 15 years) and grain (aged for 0 to 8 years) whiskies, and of shochu (aged for 1 to 21 years) and awamori(aged for 0 to 10 years) of Japanese traditional spirituous liquor, and commercially available whiskies (aged for 5 to 21 years) and brandies (aged for 5 to 45 years). Through the examination of proton exchange rate based on 17O-NMR half width - pH curve plots, it has been found that the minimum proton exchange rate increases as the period of maturation of liquor becomes longer.

Commentary: A spirited attempt

Scotch malt whisky has been the subject of another study from Canada earlier this year. Lapointe and Legendre from the University of Montreal used cluster analysis to group the 109 distilleries in Scotland that produce single malt whiskies.1 Ambitious as that study was, it did not do full justice to the topic as many of these distilleries bottle at several ages and strengths. Jackson estimates that over 400 different bottlings of Scotch malt whisky exist at any time.2 Cognac is also available from many producers and in different grades —for example, three star, ive star, VSOP, XO, Napoleon, and vintage. So this paper, by Campbell et al, in considering just two malt whiskies and two cognacs, hardly constitutes even a pilot study of this subject. The malt whiskies chosen for the study were Gleniddich and Springbank. Gleniddich, from Dufftown, is the world's best …

Agglomeration of ethyl esters in model spirit solutions and malt whiskies

AbstractMedium‐ and long‐chain ethyl esters were found to have a limited solubility when model spirits and malt distillates were diluted to 230 ml ethanol per litre for sensory analysis. At concentrations above this critical level the concentration of esters in solution remained constant, with the excess esters forming agglomerates. The saturated nature of the solution reduced the volatility of other esters, with a proportion of these compounds being partitioned into the agglomerate. The distribution was dependent on the mole fraction of each ester and its activity coefficient. Dissolution of wood extractives caused a number of changes in the solubility parameters of organic compounds; activity coefficients were increased and both the concentration and activity at which agglomeration occurred were decreased. This resulted in lower solution concentrations with increased concentrations in agglomerates. The reductions in free solution concentration could result in lower headspace concentrations, and thus have a direct effect on the flavour of the matured spirit.