During the 17th and 18th century the main cereals grown in Scotland were barley, oats and rye. It is likely that all of them were used to produce distilled spirits (and whisky), although barley was probably favoured for its better enzyme activity. Additionally oats had too much husk for efficient mashing and rye tended to produce excess yeast growth. Mixed fermentations were probably often used, after all distilling was merely a way to preserve excess crop. Martin Martin in 1702 describes the practice on the Isle of Lewis: "The corn grown here is barley, oats and rye... Natives brew several sorts of liquors; as common Uisquebaugh, another called Trestarig, id est Aqua Vitae, three times distilled, which is strong and hot; a third sort is four times distilled Uisquebaugh-baul; id est Uisquebaugh...The Trestarig and Uisquebaugh-baul are made of oats". The oats were likely to produce a wash lower in alcohol and higher in congeners, so the process of three or four distillations makes sense. Multiple distillations were most likely used to produce palatable spirit by narrower cuts and multiple distillation, not so much to reach high alcohol strengths.
|Chevallier barley was recently revived in Norwich by Dr Chris Ridout|
|The price of maize and grain whisky (Weir 1995)|
The pot-still malt whisky distillers were more traditional, even superstitious in their grain purchases compared to brewers and grain distillers. They used mostly local barley throughout the 19th century, although during the periods of bad harvests and/or higher whisky demands, as during the 1890's whisky boom, they were forced to use some foreign barley, mostly from Denmark, the Baltic and Morocco. There were other significant reasons pot distillers used local barley: They were trying to ban the grain distillers from marketing grain spirits as whisky or Scotch and proposed that only whisky made from Scottish grain could be called Scotch. The local farmers also bought much of the draff (waste product of the first distillation, great cattle feed) from the distilleries, so both benefited from direct sales to each other without any mediators. One likely explanation for the local sourcing of barley is the traditional and frankly sometimes superstitious approach on any improvement or change of the process or the product.
In the 1920s the prices of cereals varied widely and grain whisky was made from various ingredients based on the world market. Barley from California and Canada (small 6-row), maize from US and Argentina, oats from Scotland and Canada, even Brazilian manioc were used. The column grain distillers used the cheapest available raw materials, for example the maize bought from USA was usually grade 3, while the US domestic distillers used grade 1-2 maize.
During the WW II, Danish Kenia was grown widely for its better yields, however it was not good for malting and after WW II Pioneer (Kenia x Austrian Tshermarks) and Proctor (Plumage-Archer x Kenia) dominated until 1960 with a acreage up to 70%, although DCL seems to have preferred Zephyr. Due to rapid growth in whisky production in the 1950s, more English and foreign barley was used. If six-row barley was used, the smaller grains were sold to the distillers (more enzymes) and the plumper grain (more yield) to the brewers. Golden Promise and Maris Otter were introduced in 1965. Golden Promise became the barley of choice for distillers for its yield and enzyme activity until 1980s and Maris Otter was the brewers' malt, allegedly for its flavour. In the 1980s German Triumph and its many hybrids (Corgi, Natasha, Optic, Prisma, Camarge) surpassed the Golden Promise for their better yield and some winter varieties were introduced in Southern Scotland (Melanie, Halcyon, Regina). After that many different varieties have been developed and the suitable varieties for distilling and brewing are declared annually by Institute of Brewing and Distilling.
|Improvement of spirit yield (Russell, 2003)|
Recently old varieties have been revived, mostly due to growing craft beer movement, but also by some malt distilleries. Bere barley was used in whisky production in Highland Park until 1926 and has since been used mainly for bere bannocks, but also for malt whisky. Bere was 6-row barley variety originating probably from northern Scandinavia with long stem and rapid growth (therefore also called 90-day-barley). Michel Couvreur revived the bere whisky in 1985 when he used bere from Orkney to distill whisky at Edradour. Since then at least Arran, Springbank and Bruichladdich have released bere whisky.
Sadly, there are no scientific comparisons between the flavour of different barley varieties. The early malting varieties were proportionally higher in protein and fat but lower in carbohydrates. Steeping times were much longer, probably because lack of knowledge and to some extent because of dormancy-prone barley varieties. The germination times were longer and the temperatures in floor maltings were more uneven than in modern maltings. These differences most likely made the wort more prone to infections of wild yeast and lactobacilli, along with mostly longer fermentations and lower starting gravity. The consistency was probably more viscous due to greater proprtion of betaglucans to alpha-amylases. So the wort was likely to have more husks, dead yeast, autolysis products, lactobacilli, oils, diacetyl, esters (from acids and alcohols) and thicker in consistency causing easier burning in the wash still. The result was likely to be oilier, more sulphury and fruity spirit with more higher alcohols (fusels) and more furfural (from the husks, providing nutty aroma), assuming that the other factors were kept constant. It is unlikely that there are considerable differences within the modern barley varieties in terms of distilling, since the spesifications for malting barley are quite strict. However, there is proof that the change of barley variety also changes the lactobacilli flora in the distillery, which might have at least some effect to the spirit if long fermentation times are used. The practice of malting (floor malting/industrial malting) has probably greater effect on flavour than the barley variety.
|Maize mill at Dumbarton (I.Hume)|
Agu RC et al. Production of grain whisky and ethanol from wheat, maize and other cereals. J Inst Brew 2006;112;4;314-323
Beal, AD & Mottram DS. Compounds contributing to the characteristic aroma of malted barley. J Agric Food Chem 1994;42;2880-4
Biernacka P & Wardencki W. Volatiole composition of raw spirits of different botanical origin. J Inst Brew 2012;118;393-400
Beaven, ES. Barley. Duckworth 1947
Bringhurst TA. Barley research in realtion to Scotch whisky production. J Inst Brew 2015;1;1-18
Brookes, P. Barley Breeding and development in the UK, an historical perspective. Brew Hist 2005;121;25-39
Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Campbell I (ed). Proceedings of the Third Aviemore Conference on Malting, Brewing and Distilling. Intitute of brewing, 1990.
Collins TS et al. Profiling of nonvolatiles in whiskeys. Food Chem 2014;163;186-196
Cramer ACJ et al. Analysis of volatile compounds from various types of barley cultivars. J Agric Food Chem 2005;53;7526-31
Dong L et al. Characterization of volatile aroma compounds in different brewing barley cultivars. Sci Food Agr 2014
Gous PW et al. Drought-proofing
Hoff S et al. Influence of barley varieties on wort quality and performance. J Agric Food Chem 2013;61;1968-76
Lloyd, WJW. Adjuncts. Centenary review. J Inst Brew 1986;92;336-345
Mallett, J. Malt. Brewer's Publications 2014.
Martin, M. A description of the Western Isles. 1702
Martin, P & Chang, X. Bere whisky- rediscovering the spirit of an old barley. Brew Dist Int 2008/4;6;41-43
Mather, RT & Willkie, RT. Distillers' grain manual. Seagram, 1942
Piggott JR et al (ed). The science and technology of whiskies. Longman 1989
Priest, FG & Campbell I (ed). Current developments in brewing and distilling. Aviemore conference 1982.
Robson, F. Cameronbridge, a distilling giant. Brewer Int 2001;1;4;16-19
Russell I (ed). Whisky, technology, production and marketing. Academic Press 2003
Weir, RB. History of the Distillers Company 1877-1939. Oxford 1995.