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Human experience with barley has been well established for several millennia and barley research has been fundamental to our understanding of raw materials for malting, brewing and distilling. Distillers have long been indebted to malting, brewing and distilling researchers for information on barley (and malt) relevant to their operations. Originally distilling barley research was focussed on the parameters defining barley quality and plant performance, but it has developed to further our understanding of the properties and genetics of barley and malt. Through the years, several strategic milestones can be identified showing a progression of related research themes, culminating in our current state of knowledge of barley. These include the development of the fermentability method, together with the biochemistry and enzymology underlying starch and cell wall hydrolysis, which resulted in a greater understanding of processing properties and subsequent improvements in performance. Ethyl carbamate is a barley-derived carcinogen present in a range of potable spirits, which has been a concern for distillers; the identification of the genetic marker for the barley precursor epiheterodendrin laid the foundations for the application of modern (non-GMO) genetics to developing improved barley varieties, which will benefit the whole supply chain. Together these approaches underline the mutual interdependence of applied research and genetic approaches in achieving substantial advances in our knowledge. Copyright © 2015 The Institute of Brewing & Distilling

J. Inst. Brew. 117(2), 156–165, 2011 Three cases of Mackinlay’s Rare Highland Malt whisky were excavated from the ice under Sir Ernest Shackleton’s 1907 expedition base camp hut at Cape Royds in Antarctica in January 2010. The majority of the bottles were in a pristine state of preservation and three were returned to Scotland in January 2011 for the first sensory and organoleptic analysis of a Scotch malt whisky distilled in the late 1890s. Sensory analysis and the higher alcohol and maturation congener profiles describe a lightly peated malt whisky matured in American white oak sherry or wine casks. Analysis of process related compounds together with combined gas chromatography (GC) mass spectrometry and GC-olfactometry analysis of fermentation related congeners show a distinctly ‘modern’ style of malt whisky. While Scotch malt whisky at the end of the 19th century was generally regarded as heavily peated and harsh in character, Charles Mackinlay & Co. Distillers were producing a malt whisky with an altogether more subtle character at their Glen Mhor distillery near Inverness. The sensory and chemical analysis of this unique whisky artefact significantly changes our understanding of the quality and character of Scotch malt whisky produced by our distilling forefathers.

The authenticity of a specific brand of Scotch whisky may be confirmed by comparing analytical data for suspect samples with reference to analytical ranges for the genuine brand. Wider generic authenticity issues exist when a product purports to be Scotch whisky when it has not been produced in Scotland in accordance with the legal definition of Scotch whisky. When such cases reach litigation, courts may ask chemists to analyse suspect products and draw conclusions on authenticity. This paper presents analytical profiles generated from a survey of Malt, Grain and Blended Scotch whiskies and compares the results with whiskies of other origins and examples of a diverse range of suspect products purporting to be Scotch whisky. The concentrations and ratios of concentrations of the major volatile compounds (or congeners), particularly methanol, n-propanol, isobutanol and 2- and 3-methyl butanol, were found to be important factors in the authenticity decision-making process. In addition, the absence of known Scotch whisky congeners, the presence of compounds known to be absent from genuine whisky and abnormal maturation congener profiles all contributed to the decision process. From this review of genuine analytical profiles, an experimental protocol for determining the authenticity of Scotch whisky is proposed.

Traditionally, distilling companies in Scotland have employed a very limited number of yeast strains in the production of alcohol for Scotch whiskies. Recent changes such as the decline in availability of brewers' yeast as a secondary yeast strain and the availability of yeast in different formats (e.g., dried and cream yeast as alternatives to compressed yeast) have promoted interest in alternative Scotch whisky distilling yeasts. In previous work, we investigated different strains of yeasts, specifically Brazilian yeasts which had been isolated from and used in fuel alcohol distilleries. One of the Brazilian yeasts (CAT 1) showed a comparable fermentation performance and superior stress tolerance compared with a standard commercial Scotch whisky distilling yeast (M Type). The Brazilian CAT 1 yeast isolate was further assessed in laboratory scale fermentations and subsequent new make spirit was subjected to sensory analyses. The spirits produced using the Brazilian strain had acceptable flavour profiles and exhibited no sensory characteristics that were atypical of Scotch whisky new make spirit. This study highlights the potential of exploiting yeast biodiversity in traditional Scotch whisky distillery fermentation processes.

J. Inst. Brew. 115(2), 128–133, 2009 Hull-less (or husk-less) barley is possibly one of the most impor-tant developments in barley in recent years. This study looked at the potential of hull-less barley for use by the Scotch whisky industry. By modifying the malting conditions for hull-less bar-ley, it was possible to provide good alcohol yield as well as sig-nificant improvements in processing characteristics. The bio-chemistry controlling the germination of hull-less barley was consistent with established knowledge about ‘normal’ hulled barley except that care is needed to ensure the consistency of feedstock, particularly since hull-less barley may be prone to embryo damage during harvesting in the field. Our results indi-cated that the new batches of hull-less barley studied, produced malt that gave much improved mash filtration rates in compari-son with previous batches of material. These experiments demonstrated that by changing the malting conditions, to give a much shorter steeping cycle (8 h), it is possible to reduce water usage substantially in the malting industry, since only one ‘wet’ cycle was used, and also reduce germination times since opti-mum alcohol yield was achieved on day 4 germination rather than day 5 for conventional husked barley. This could save costs in terms of water, energy and time for the malting industry. The study also confirmed the potential of hull-less barley for provid-ing significant benefits for Scotch whisky distillers, both in terms of higher alcohol yields, and increased throughput, by showing that it is possible to overcome some of the filtration issues that have been previously associated with hull-less barley. This study indicated that the new material was better suited than previous batches to both malt and grain distilling, both in terms of enzyme development and potential distillery performance, and further showed that viscosity problems associated with grain distillery co-products can be significantly reduced when using hull-less barley malt in the grain distillery. These would be sub-stantial potential benefits for the Scotch whisky distilling indus-try.

It is not known if peats derived from different areas of Scotland have distinctive chemical constituents that could impact on malt whisky in discernible organoleptic ways. Fourier transform-infrared (FT-IR) spectroscopy was used as a high throughput screening method to investigate discrimination of a large number of peat samples from six different geographical origins around Scotland. The data were analysed statistically (using principal component-discriminant function analysis) and the results showed a difference between peat samples from different geographical origins. Therefore, we have shown that FT-IR spectroscopy provides a quick and simple method for differentiating peat types.

Sensory panels are used widely in the Scotch Whisky industry in a range of applications. Sensory data can play a key role in monitoring product quality or advancing flavour understanding. Therefore, the quality of this data must be high. Standard procedures for sensory evaluation outline requirements for experimental design, selection and training of panellists, and sensory room design. However, there are certain aspects of sample preparation and handling, specific to the assessment of whisky, which are not covered by these standards. This paper describes a programme of research aimed at examining these factors and their potential impact on sample condition. The results of this study have been collated, to produce guidelines for the preparation and handling of sensory samples in the Scotch Whisky industry. Following these guidelines should aid in the optimisation of sensory data quality.

Limit dextrinase, is an important enzyme in the hydrolysis of starch from cereals to fermentable sugars. Work is described which demonstrates the importance of this enzyme in the production of Scotch whisky. The study considers the occurrence, survival and action of limit dextrinase (total and free) during fermentation in malt and grain distilleries. The results of both laboratory and distillery studies revealed that limit dextrinase can survive the conditions encountered during mashing and is not only present in the fermenter but its activity can increase during fermentation. This observation has important implications for the production of Scotch whisky, since the fermentation substrate (wash) is not boiled, the enzyme is therefore available to degrade dextrins into fermentable sugars, and can potentially increase the yield of alcohol.

Application of high performance anion chromatography (HPAEC) to distillers worts was able to resolve a series of individual fractions (A, B, C, D, E and F) which eluted between α(1-4) linear dextrins (DP4-7) and which were ubiquitous in worts. Their positions in the chromatogram and their behaviour suggested that they might be α(1-6) branched dextrins. Two of these fractions (C and D) were purified and shown to be α(1-6) branched dextrins by treatment with an α(1-6) debranching enzyme (pullulanase). Further characterisation by HPAEC and Matrix Assisted Desorption Ionisation/Time of Flight (MALDI-TOF) mass spectrometry revealed that the unknown fractions, C and D, were α(1-6) branched dextrins consisting of 6 and 7 glucose units respectively. Possible structures were suggested for these two fractions and it was shown that they were comprised of maltosyl and maltotriosyl branches attached by α(1-6) links to maltotriose, maltotetraose and maltopentaose. The behaviour of these dextrins was studied in the context of the Scotch whisky process under both laboratory and production conditions and they were found to be important substrates for the debranching enzyme, limit dextrinase, during fermentation. The study of these dextrins provided a useful tool for monitoring the effects of enzymes (α-, β-amylase and limit dextrinase) in the Scotch malt whisky production process.

Sensory profiling of Scotch whiskies, important for research and product analysis, requires training of assessors including the identification of important whisky aroma characters. Seventeen compounds were selected as potential reference standards for common whisky sensory characteristics. Nineteen assessors determined detection and recognition thresholds for each reference standard dissolved in 3 year old grain whisky at 23% (v/v) ethanol using both ascending dilution series and Latin square presentations. With the former, order effects and errors of habituation and anticipation were apparent. However, the Latin square presentation was satisfactory for threshold measurements in whisky, yielding good correlations and reproducibility, and enabling outliers to be reassessed independently. Slopes obtained from plotting probit against concentration for detection and recognition data, psychometric functions of aroma perception, varied between reference compounds and 90% recognition concentrations were obtained for each aroma standard. Sixteen of the compounds assessed were suitable for use as reference flavour standards for training of whisky assessors.

The growth of representative strains of lactobacilli in a laboratory scale distillery fermentation has been examined. Some strains were particularly deliterious to the fermentation and were responsible for reducing the final pH, increasing the final gravity and reducing the alcohol concentration in fermented wash. The effects of varying degrees of infection by one deliterious strain and one innocuous strain were studied in more detail. Spirit yield depended on strain and inoculum size. In all cases the concentration of lactic acid was increased and the balance of other organic acids was disturbed by the presence of the bacteria.

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.

The isolation and identification of the substances which contribute to the aroma and flavour of Scotch whisky have been attempted by means of distillation and gas chromatography. Selection of a butanediol succinate column from a number of widely used gas chromatography separating columns, in conjunction with temperature programming, resulted in excellent peak resolution for the essential oil portion.