Editor’s Note: This is the second in a nine part series chronicling the life of James Crow, an extremely important figure in the history of American whiskey. A chemist originally from Scotland, he is credited by some as having invented the sour mash process. Watch this time slot on Thursdays (11am Pacific Time) for the other articles.
State Of Production Knowledge, Practices And Equipment In Crow’s Time
Outside the classrooms of Edinburgh University, Scotland’s whisky trade was a world leader in grain distilling technologies and manufacturing since the late 1780s. From the 1600s, the Dutch were world leaders in distillation equipment and processes, developing the vodka industry in East Europe (1580s), the French brandy in the Charente (1600s), rum in Brazil (1620s) and in the West Indies (1630s).
Flemish refugees escaping the Low Countries lay the groundwork for London gin production from the 1590s. Dutch technology and ideas not only played instrumental roles in the British malt spirits, but their influence also shaped the Scotch whisky industry with personnel and training. Distillers such as Robert Haig of the Scotch whisky dynasty studied in the Netherlands before distilling gin on his Throsk farm in the 1640s. The Dutch exported distillers, such as Henricus Van Wyngaerden who was recruited by the Honourable Society of Improvers of Agriculture in Scotland to advance Scottish grain distilling in the 1740s.
By 1822, Scotland had 111 licensed distilleries and ten rectifiers; plus, a thriving illicit trade that saw 20,297 excise prosecutions and 4,867 convictions of illegal stills the same year. Pure malt and mixed grain spirits were slowly transitioning into cask maturation and beginning to resemble the character of modern Scotch malt whisky. Local Scotch pot still whisky monopolized over ninety per cent of home spirits consumption, about two and a half million proof gallons; the Government estimated with illicit Highland production the volumes more than double. The year Crow left Scotland, the Excise Act of May 1823 reduced domestic duty by a third and set-up regulatory frameworks for the genesis of the modern Scotch industry.
Scotch industry practices of the time provide valuable insights into Crow’s level of product knowledge and how he applied his expertise to American whiskey manufacture. Unlike America, British Government regulations carefully monitored every aspect of production to ensure full compliance to maximize excise revenue. From grain to cask Government inspectors and distillers thoroughly documented each manufacturing stage to prevent deception and account for mishaps. Such scrutiny gave Crow prescriptive details on all aspects of the manufacture of whiskey. While variations in grain, scale and process occurred by region and distillery, it is possible to summarize how the Scotch industry broadly operated to observe some of the ideas and disciplines Crow brought to his American endeavors.
Distilling season: The colder Scottish climate meant a more extended distilling season of over three hundred days, compared to the US’s shorter season of about two hundred days. Both countries incurred disruptions due to breakdowns, cleaning, repairs and accidents, along with contaminated washes and fouled distillation runs robbing them of maximum output to the distillery’s annual capacity. One of the significant variables Crow needed to accommodate was Kentucky’s hot and humid climate which could detrimentally affect malting, fermentation, distillation and maturation outside the colder winter months.
Grain: With most Scottish distilleries, it was common practice to mash grains with malted barley, usually 25% to 50% of the mash with raw barley or bere, sometimes oats and rye. The 1770 Malt Tax, not repealed until May 1851, made an all-malted barley mash prohibitive for many distilleries. The importation of cheaper American corn was used by the large Lowland distillers who also mashed local grains with mixtures of peas, turnips and other saccharine rich vegetables.
The most notable differentiation between America and Scotland was the cultivation of bere and peat fuel for malting. The bulk of the barley used in the Highlands was the six-row local bere landrace, although, in Western Scotland, oats dominated mash bills. Wheat was too expensive for distilling. The Common two-row barley and Scottish bere divide was most evident between Lowland and Highland distillers due to different tax levies, as well as access to raw materials such as Lowland mined coal and imported English grain.
Many Highland distillers and maltsters could not afford coal fuel, and Scotland’s landscape heavily deforestation into pastureland meant a scarcity of wood; instead, they use dried peat moss. The acrid smoke used in malt kilning from decomposing vegetal matter impregnated Highland and island whiskies with a distinctive peet-reek phenolic nose and creosote-like flavour.
America’s Atlantic states mashed rye and corn dominant grain bills, while in the Western states corn dominated grain bills, with malted barley or rye representing less than twenty per cent of the mash.
Malting & grinding: Commercial maltsters and large brewers in Britain prospered with the mass production of beer in the 17th century. Skilled beer maltsters developed sophisticated malting specifications for different styles of beers, from pale ales to London’s popular dark porter, transferring their malting proficiencies to the whiskey industry.
The invention of steam power to drive traditional English and French millstones represented new efficiencies compared to conventional waterwheels, wind or livestock to grind meal. When Crow arrived in Kentucky, he found the same rustic watermills and grindstone technology; it would be a half-century before the modernization of milling with steel rollers lowered costs and improved grist specifications and meal quality.
Mashing & wort: Scottish distillers followed the brewer’s practice of filtering or sparging the mash to capture the dissolved sugars in a liquid called wort. Instead of boiling the wort before fermentation, distillers allowed the amylase enzymes to continue to convert starch into sugar into the fermentation producing a lower gravity with a slightly higher alcoholic content. This process resulted in a weaker wash with a higher specific gravity that made a cleaner, better tasting and stronger wash better suited for distilling.
Strong washes of high gravity shared similarities to distilling-on-the-grain, a consequence of America’s mixed grain mash bills that was due to their higher concentration of suspended particles and grain oils. Early Kentucky distilleries attempted unsuccessfully to filter the mash through corn cobs and oat husks to extract a wash, as weaker washes also reduced scalding during distillation.
The higher levels in grain oils in American mashes, notably corn, also produced more fusel alcohols and congeners during distillation impacting on the whiskey’s palatability and unpleasant physiological effects for the drinker.
Yeast & fermentation: In Britain, brewer’s required yeast apprentices to train for five years to attain proper schooling in the care and propagation of yeast strains for maintenance of flavour and alcoholic yield. When distilling shifted from a cottage industry into a commercial enterprise, yeasting skills pivoted to accommodate worts that maximized alcoholic strength with cleaner ferments.
When Lowlands distilling rapidly expanded from the 1780s, they needed large volumes of yeast. London breweries served this demand shipping puncheons of compressed London porter yeast daily to meet the substantial requirements of these new large distilleries that were rapidly distilling a crude spirit for export to English rectifiers. The yeast often arrived in a state of putrefaction, making high gravity wort a slightly more heat-tolerant strain yielding a slightly stronger alcoholic wash.
In the Highlands, the smaller distillers obtained yeast from one of Scotland’s 250 ale breweries and called ‘sweet Scotch yeast’. If unable to access brewer’s yeast a distiller used household baking yeasts or cultured batches by boiling a slurry of malt meal to inoculate a bootstrap strain; this rustic method exacerbated the risk of contamination.
In Kentucky, Crow’s diligent study of sour mash fermentation led to the improved management, recycling and control of the distillery’s strain of Saccharomyces cerevisiae.
Distillation equipment and running the still: Scotland’s 1786 Wash Act charged the distiller an annual fee per cubic gallon on the stills’ capacity, not on the yearly production. This regulation compelled large Lowland distillers to invent rapid distillation techniques using shallow stills to constantly circumnavigate the law by increasing the number and frequency of charges per day. Studying in Edinburgh, Crow would have been aware of the developments in shallow still fabrications and educated in the traditional pot still principles universally practised on Highland and small scale Lowland distilleries.
In the Highlands, most stills were heated by dried peat with distiller manually working the still slowly, enabling the distiller to cut the middle runs more judiciously. Scottish coppersmiths procured affordable supplies of English and Welsh rolled copper, with most stills and worms tin-plated for longevity.
1822 was the penultimate year before the 1823 Excise Act abolished the gallon capacity license fee, replacing it with the volume of spirits distilled. It also presaged the arrival of experimental apparatuses engineering continuous distillation, capable of generating much higher volumes at a much higher proof, what the trade called ‘silent’ spirit. In 1826, John Stein built his first continuous still at the Kirkliston distillery, while in Dublin at the Dock distillery, Aeneas Coffey’s prototype continuous column stills were evaluated by the Board of Excise.
American distilling designs and materials took a different trajectory, due to the rapid adoption of steam boilers, the varying grain recipes and the economic appeal of patented wooden still fabrications purpose-built for distilling on the grain. Until America established a copper refining industry in the 1830s, the Government’s 25% tariff on import English copper meant this valuable metal was used sparingly. In the 1830s, Britain started adopting patent continuous column stills, and in America, the patent wooden charge stills came into vogue, known in Kentucky as bourbon steam stills.
Proof and casks: By the 1820s, in Scotland, there was little interest in cask maturation, although some spirit dealers and distillers acknowledged the principles of aging in cask wood for a richer, complex and mellower character, notably for brandy and rum imports. The vast bulk of Scotch whisky was consumed within a few weeks or months from production.
As exports developed in England, more discerning and wealthier customers preferred wood-aged whisky that aligned with their sensory expectations established by brandy and rum. The inflection point for cask matured whisky was the growing surplus of sherry butts. Sherry imports surged five-fold from the late 1820s to the 1870s. It proved a boon for the whisky industry with an equivalent of 1.5 million used butts to recooper into more hogsheads or refill the butts with whisky spirit.
With sherry Britain’s most popular wine, it delivered the vinous flavor bridge between French brandy and Scotch malt spirit. While imported hogsheads of rum and brandy preceded sherry (and port) for storing whisky spirit, it was the flavor of sherried wood and the later innovation of lighter flavoured blended Scotch that would transform Scotch whisky from a provincial beverage into an international commodity. British law in 1822, set the standard proof range for Scotch whisky at 1 to 10 Over Hydrometer Proof (57 – 63% ABV).
Scotch and American whiskey production variances
Crow encountered in America a different set of challenges in the manufacture of whiskey – a case of Old World whisky substantially different to New World whiskey. Surprisingly, both were contemporaries of each other. America’s first commercial distillery was established in Salem, Massachusetts by Emmanuel Downing in 1648 making rye whiskey. Scotland’s first whisky enterprise was by Duncan Forbes at the small Ferintosh distillery, near Dingwell in 1680, distilling bere (barley).
Other than the challenges in the raw materials, Crow had to adapt to more extreme climate and temperature variances in America. Of these production variables, Crow needed to accommodate five salient differences between new and old world whisky making.
Fermenting and distilling on the grain: Scottish, Irish and English distilleries extracted wort from their barley-based mash, a sugar-rich liquor, that was free of grain matter before British distillers added yeast to ferment. After the fermentation, the beer or wash was despatched to the low wines wash still for the first distillation.
American mixed grain mashes were fermented and distilled on the grain; the liquor was very challenging to separate from the slurry of mashed grain. This was because boiling water with hot backset broke down the corn’s cell walls by gelatinizing the starch granules to produce a thick mash. Adding rye’s stickiness due to gummy beta-glucans further heightened the risk of scalding during distillation when using direct fire copper pot stills.
From the early 19th century, American distilleries shifted to steam heating and triple chambered wooden stills to help mitigate these problems and also alleviate the high cost of imported copper components. Copper also interacts with undesirable sulphur compounds, removing them as copper sulphate. Whiskey made on wooden stills was inferior to copper.
Crow did not embrace the wooden patent steam still inventions in America, due to its second-rate distillate. He instructed all copper traditional pot stills and worms, guaranteeing a more wholesome and palatable spirit; how he ran the stills was crucial to avoid scalding and prevent an empyreumatic taste.
Acidity: The term pH and its scale measuring the acidity to the alkalinity of liquids was unknown until the early 20th century. While old Dutch, English and Scottish distillers did not know the concentration of hydrogen ions caused pH values, these distillers were aware of the benefits of unboiled beer and the need to ensure a small degree of acidity before distilling.
In 1743, Henricus Van Wyngaerden of Edinburgh, recruited to counsel estate distillers in Scotland, instructed, ‘Put the barm (yeast) & lees (residual pot ale from the singling run) into the still along with the liquor, but if the lees be thick, put likewise in water, or rather feints (residuum if the doubling run), to make thinner.’
Another method to adjust the pH involved rubbing the still interior with alkaline soap or animal fat which further served to reduce scalding, corrosion and also prevented the wash from foaming and reduced the risk of choking the worm.
In America, distillers called acidification of the liquor before fermentation sour mash. By 1830s, a variety of sour mash methods were in everyday use throughout Tennessee and many parts of Kentucky. The sour mashing method immigrated west with east coast rye distillers, who borrowed this technique from rum distillers. Notably, the Jamaican rum distilleries used dunder or spent distiller’s lees, to propagate yeast inoculations between batches and control micro-bacterial infections when fermenting molasses wash to make cane spirit rum.
Sediment and scalding: Scotland abandoned distilling on the grain before 1800 as it proved inefficient and caused suspended grain residue to adhere to the interior wall during the heating of the still. The scalded particles were a constant problem infusing the spirit with an offensive burnt taste. Rummagers chains inside the still prevented sticking, as well as the slow running of the still avoided the burnt flavors.
In 1794, America’s invention of the steam heated wooden charge stills permitted a thicker and stickier slurry of corn and rye mash beer to be distilled avoiding burning the spirit. By the 1820s, British and North American distilling technologies diverged to accommodate different grains, fermentation methods and distillation technologies.
Fusel oils: The term fusel did not enter the English lexicon until the middle of the 19th century; it originated from the ‘bad oils’ reported by German potato distillers. The Scots called this natural by-product of distillation catalyzed during fermentation ‘essential’ or ‘grain oils.’
Corn, in particular, contains large amounts of oil released during fermentation. To minimize these grain oils, American distillers skimmed some of the corn oil rising after fermentation, or when it surfaced as fusel oil in the low wines receiver or cistern before the second distillation. Pot still designs could reduce the volume of fusel oil and fusel aldehydes in the finished spirit as longer still necks and the angle of the lyne arm resulted in more reflux. The typical flat-topped early 19th century American still heads had little or no reflux sending fusel rich vapor through a short pipe into the condensing worm to fall as spirit into the receiver.
In large volumes, fusel oils are noxious and unwholesome; however, in small amounts, they are essential for degrading and transforming into a range of complex whiskey flavors during barrel maturation. Oxidization and charcoal filtration in charred barrels also plays indispensable roles in producing the desirable characteristics that make straight American whiskeys palatable.
Charred casks: The grain flavor compounds mashed in American whiskey are well-suited to charred, new white oak containers, whereas barley, a more delicate, malt flavoured grain benefits from second or third use casks.
In the 19th century, the carbonized membrane inside a charred barrel played a critical role in filtering out residual fusel congeners and added complex caramelized oak flavors and rich hues to the whiskey. At the same time, slow oxidization catalyzed esters and other compounds into more complex and pleasing flavors.
Charring also helped compensate for shorter periods of stave seasoning by vulcanizing any residual green tree sap notes trapped in the surface wood fibers. Britain, in the 17th century, saw a trend for slightly charred casks in the manufacture of a darker style French brandy.
By the late-17th century the pale, or the toasted cask style became more fashionable. It is unlikely Crow had any working knowledge of British coopering other than for the storage and transport of British spirits and beer.
In part 3 next week we take a detailed look at Crow’s time in America.
Chris Middleton is from the whisky industry and writes about whiskey too. After an international career in the whiskey industry he has an insider’s perspective on the history, production, product innovation and cultural marketing of whisky from manufacturing countries of Scotland, Ireland, to North America, and his home in Australia....