MODULE: DISTILLING UNIT: 11: PRODUCTION OF SPIRITS ...

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MODULE: DISTILLING UNIT: 11: PRODUCTION OF SPIRITS ...

MODULE: DISTILLINGUNIT: 11: PRODUCTION OF SPIRITSABSTRACT: This unit deals with the processes involved in theproduction of whisky, in parts of the world other than Scotland. Theproduction of gin and vodka from neutral spirit are described togetherwith the processes for the production of rum and brandy.LEARNING OUTCOMES: On completion and comprehension of thisunit you will be able to:1. Identify the differences in the production processes for whiskyproduction in Scotland, Ireland, America and Canada.2. Differentiate between the production processes used to convertneutral spirit into gin and vodka.3. Compare the distillation and maturation techniques employed inrum and brandy production with those used for manufacture ofother spirits.PREREQUISITE UNDERSTANDING: Detailed knowledge of theprocesses involved in Scotch whisky production. It is important thatthis unit is tackled only after you have studied Units 1 to 6.


Unit 11: Production of spiritsUNIT 11PRODUCTION OF SPIRITSCONTENT11.111.1.111.1.211.1.3Irish WhiskiesIntroductionHistoryProductionPage444511.211.2.111.2.211.2.311.2.411.2.5American WhiskiesBackgroundMash Bill and MashingFermentationDistillationMaturation77910101211.311.3.111.3.2Canadian WhiskyBackgroundProcess13131311.411.4.111.4.211.4.3GinBackgroundProcessBotanicals1414151611.5Vodka17© 2001 The International Centre for Brewing and Distilling 2


Unit 11: Production of spirits11.5.111.5.2BackgroundProduction171811.611.6.111.6.2RumGeneralProduction19191911.711.7.111.7.2BrandyGeneralProduction of Cognac and Armagnac21212111.8Summary of Key Points2411.9Self Assessment Questions2511.10Self Assessment Answers26© 2001 The International Centre for Brewing and Distilling 3


Unit 11: Production of spiritsToday there are three distilleries in Ireland. Bushmills in CountyAntrim in the north, Midleton near Cork in the south (both of thesedistilleries are now part of the French drinks group Pernod Ricard)and the Cooley Distillery in County Louth near the border, which wasre-opened in 1989. Between them these three distilleries produceover 60 brands.Irish whiskey is often described as being distinctive because of tripledistillation and the fact that it is unpeated. Neither of these claims iswholly true. Certainly in the 1880’s, at the time of Barnard’spublication, he reported that quite a few distilleries employed doubledistillation and today the Cooley Distillery continues this tradition.Peat was used in the mid nineteenth century for malt kilning but aslighter whiskies gained popularity so closed kilns were adopted suchthat hot air, and not smoke, dried the malt. So the use of peated maltdid die out for a substantial period but it has now been re-introducedat the Cooley Distillery, which is marketing a brand positionedalongside the heavy Islay malts.KEYPOINT: While Irish whiskies are generally characterised bytriple distillation and unpeated malt, there are exceptions toboth of these distinctive features.11.1.3 Production.It is a feature of Irish whiskey that only barley grown in Ireland isused.The preparation of Irish all malt wort and its fermentation are identicalto the processes used in Scottish malt distilleries.Wort preparation for pot still whiskey employs a mixed grist of maltand unmalted barley (up to 60%). The unmalted barley is either wetmilled or hammer milled and given an infusion mash into mash tuns,which are generally larger than those found in Scotland because theymatch the greater capacity of the Irish stills.Wort for grain spirit is produced from a mash of about 90% maizeand 10% malt (although use of enzymes is allowed in Ireland theyare only used in neutral spirit production). The maize is hammermilled, slurried, and then cooked at 150°C in a continuous flowingsteam jet cooker. After cooking it is blended with malt in a continuousplug flow system before entering fermenter. This system is used to© 2001 The International Centre for Brewing and Distilling 5


Unit 11: Production of spiritsmeans that the casks stand on their ends. These warehouses reducelabour requirements but make it more troublesome to removeindividual casks.Blending in Ireland is not such a complex exercise as in Scotland (infact the Irish distillers prefer to use the term “vatting”) because of thelimited sources of supply but the distilling of different types of spirit inthe same distillery gives rise to a wide range of products. Thus wehave single malts, blends of malt and grain whiskies, single pot stillwhiskies and blends of pot still and grain whiskies.11.2 American Whiskies.11.2.1 Background.The first bourbon was probably made when Scots/Irish settlersmoved west from Virginia into the new frontier area of Kentuckyattracted by offers of land, and even the possibility of illegallyavoiding spirit taxes. Although Kentucky was a fertile area, rye wasnot grown and the main crop was corn. The settlers produced cropsbeyond subsistence levels and converted the excess into alcohol,adapting their recipes to incorporate corn. The local market for spiritwas soon saturated so they had to look further afield and shipping toNew Orleans became the established route. Shipping required casksand second hand barrels would have been the initial choice withpurging by fire to remove undesirable flavours. The casks werestamped with their point of origin, Bourbon County, and the whiskeywas referred to as bourbon.Whiskey lore tells us that Rev Elijah Craig, a Baptist minister devisedthe first grain formula and used the first charred barrels. Anotherimportant figure was Dr James Crow from Edinburgh, who introduceda scientific approach to bourbon production, and refined the sourmash process. He too is associated with the pioneering of charredcasks.The establishment of commercial distilleries did not lag much behindScotland. The first distillery is alleged to have started in Lexington in1776 and of the current distilleries Maker’s Mark and Labrot andGraham claim dates of 1805 and 1812, respectively. The use ofcasks for maturation is first recorded in 1818 while in Scotland thefirst reference is in “The Diary of a Highland Lady” written byElizabeth Grant in 1822.The general definition of whiskey set by the US Bureau of Alcohol,Tobacco and Firearms is “a spirit aged in wood, obtained from a© 2001 The International Centre for Brewing and Distilling 7


Unit 11: Production of spiritsfermented mash of grain”. Although any grain can be used maize(corn), rye, and malted barley are the main constituents with wheatplaying a less prominent role.Bourbon, rye and wheat whiskies must contain at least 51% ofmaize, rye or wheat respectively and be aged for at least two years innew charred oak casks at a strength below 62.5% abv. Corn whiskeymust contain not less than 80% corn (maize) and be matured in newor used oak casks but the new casks must not be charred. Enzymesare not prohibited though no distilleries acknowledge their use.Addition of colouring material is not allowed.There are two main production areas, Kentucky (with 10 distilleries)and the neighbouring state of Tennessee. Tennessee whiskey canbe considered a sub-species of bourbon and is produced by twolarge distilleries (Jack Daniels and George Dickel – though the DickelDistillery has been out of production for a few years).The thirteen year period of Prohibition (1920 – 33) decimated thedistilling industry in the USA; during the Second World War distilleryoutput was switched to the manufacture of industrial alcohol, andonly after that did the industry get back on its feet and begin to takeits present shape.The distinctive aspects of the bourbon process are:1. Use of limestone water, high in calcium ions2. Mix of three cereals in the mash bill3. Use of backset or sour mash4. Mash vessel with heating and cooling which allows a mashtemperature programme to follow the declining gelatinisationtemperatures of the unmalted cereals and then the adjustment oftemperature for the addition of malt5. Use of distillery owned yeast strains6. Continuous distillation7. Maturation in new charred oak casksThere are of course several variations on this theme but the onlysignificant exception is at the Labrot and Graham Distillery where potstills are used in a batch process. Interestingly the continuous stillsused in bourbon production are not normally operated round theclock and are started up each morning, with most distilleriesoperating a two shift system on a five day week. Contrastingly inScotland the batch pot stills tend to be operated round the clockapart from weekends.© 2001 The International Centre for Brewing and Distilling 8


Unit 11: Production of spiritsAlthough in America whiskey is usually spelled with an “e”, there aresome exceptions - such as Maker’s Mark in Kentucky and GeorgeDickel in Tennessee, which use the Scottish spelling for their brands.11.2.2 Mash Bill and Mashing.The mash bill for a typical bourbon whiskey would be 70% maize,18% rye and 12% malt. Wheat can be substituted for rye and is saidto give a softer flavour- Maker’s Mark is a wheated bourbon with 16%wheat in the mash bill. A Tennessee distillery would use more maizethan one in Kentucky, say 80%, with the other components at 10%each.A rye whiskey would be produced from say 51% rye, 39% maize and10% malt.KEYPOINT: Bourbon must contain 51% of maize and be aged forat least two years in new charred oak casks at a strength below62.5% abv.Hammer mills are usually employed because of the high proportionof hard unmalted cereals. The unmalted cereals must be cooked togelatinise the starch and this is usually carried out at atmosphericpressure in a batch cooking vessel. The batch cooker would typicallybe a cylindrical vessel with cooling coils positioned around a centralheavy duty stirrer. The general practice is to mash the maize firstwith a small quantity of malt, which lowers the viscosity and preventsthe formation of doughballs. The temperature is then raised from say60°C to 100°C by means of direct steam injection. After a stand ofabout one hour the mash is cooled to about 75°C and the rye isadded. There then follows another short hold and then thetemperature is reduced to about 65°C for the addition of malt.A widespread technique is that of backsetting; this is the re-use ofthe spent wash from the still as mashing liquor. The spent wash iscentrifuged to reduce solids and maintained at high temperature toensure sterility. This technique offers energy savings and effluentreduction but its main effect is to lower the pH in the mash to say 4.5.As much as 25% of mashing liquor can come from backsetting, atechnique which is also known as “sour mash”.There is no separation of wort from grain solids so a mash or lautertun is not required.© 2001 The International Centre for Brewing and Distilling 9


Unit 11: Production of spirits11.2.3 Fermentation.Most distilleries maintain their own yeast strain, unlike Scottishdistilleries who buy their yeasts from a very limited number ofsuppliers. A recent development in the USA is that a few distillerieshave licensed manufactures to supply the distillery strain in driedform.KEYPOINT: Most American distilleries maintain their own yeaststrains.Yeast is propagated in a grain based medium, usually a mix of maltand rye. Most distilleries incorporate a “souring “ of the mediumeither by use of backset or by dosing with lactic acid bacteria(L.delbrueckii); this brings about a pH reduction to about 3.8. Themedium is sterilised to kill the bacteria before the yeast is added andgrowth takes place in sterile conditions. The vessel used for growth isknown as a “dona tub”. There will be several stages of propagationbefore the yeast is held in an attemperated vessel to await pitching.The logic is that as the yeast is going to ferment an acid sour mash, itshould be grown and acclimatised in similar conditions.Fermenting vessels are frequently open wooden tubs, though somedistilleries have converted to enclosed stainless steel fermenters.Fermentations are quite slow, in excess of 72 hours, and aretemperature controlled in the more modern distilleries.11.2.4 Distillation.Continuous distillation using a single column is the common processin the USA. The exception is the Labrot and Graham Distillery inKentucky which has copper pot stills arranged to give a tripledistillation. In contrast to the procedure in Scotland with pot stills thewash contains a high level of solids with both grain and yeast debris.KEYPOINT: American whiskies are almost exclusively produced bycontinuous distillation in a single column followed by a furtherdistillation in a doubler.© 2001 The International Centre for Brewing and Distilling 10


Unit 11: Production of spiritsIn the more common process, the wash, containing cereal solids andyeast, is pumped into the upper section of the beer still column aboutsix trays from the top with steam being introduced at the bottom. Thisproduces a slightly rectified spirit of low wines in the region of 55%abv, which is subsequently subjected to a second distillation in a“doubler”. A doubler is a large kettle (typically 8ft in diameter andabout 8ft high with a refux pot on the top rather similar in shape to analembic still), where the liquid is maintained at a fixed level andheated via a steam coil, giving a distillate of about 70% abv. Thespirit must be collected at below 80% abv (if it is collected atconcentrations higher than this it has to be called “light”whisky). Thisdistillate contains a higher level of congeners than new make spirit ina Scottish malt distillery.A distillation flow chart is shown in Figure 1.Figure 1. Bourbon whiskey distillation system.In some distilleries the doubler is replaced by the so-called“thumper”. Thumpers resemble doublers but their function is differentas they do not perform a secondary distillation. The vapour from thecontinuous still is not condensed and is simply bubbled through asmall depth of water.© 2001 The International Centre for Brewing and Distilling 11


Unit 11: Production of spirits11.2.5 Maturation.Tennessee whiskey undergoes a unique step before being filled intocask being mellowed by passage through maple charcoal filters inwhat is known as the Lincoln County Process. Papers are inexistence showing that it was in use as early as 1815 in Kentucky,but why it caught on in Tennessee and not Kentucky remains apuzzle.The charcoal is prepared at the distillery from 4ft slats of locallygrown hard sugar maple. A rick is built and set alight for about fourhours. It is quenched with water and the charcoal ground to an evenconsistency with pieces about the size of marbles.The filter tanks are about 12 feet high and 6 feet in diameter and arepacked with maple charcoal. The spirit is dripped onto the top of thebed from a fixed sparge arrangement and takes 4 - 5 days topercolate through. An individual tank will be operated for about 7weeks before the charcoal has to be replaced.This process mellows the spirit before the maturation begins.The freshly charred oak cask is a unique feature of the bourbonmaturation process. The depth of charring in the cask determines thecolour of the whiskey and there are four grades of charring. Theheaviest char (Grade 4) is known as “alligator skin” because of itstexture. 25 – 30% of the colour is extracted in the first six months.With most bourbon spending about 4 years in cask, the colourchanges from colourless to light yellow, to deep yellow then toamber. The charring also releases vanillin which gives bourbon itsdistinctive vanilla notes.The strength of spirit at maturation varies between distilleries but atleast two use a strength of 55% abv, which of course is expensiveboth in terms of casks and space in warehouse.Warehousing is carried out at significantly different temperatures tothose in Scotland and some modern warehouses are heated in thewinter. Average temperatures in a Kentucky warehouse can be in therange 18 – 23°C compared to about 10°C in Scotland. Thematuration process is accelerated by the higher temperatures and inthe much drier climate in Kentucky and Tennessee alcohol levelsgenerally increase during warehousing as greater quantities of waterare lost by evaporation. A bourbon cask will generally increase instrength by 5% abv over about 6 years. Volume losses are as highas 10% in the first year and 3 –5 % per annum thereafter.© 2001 The International Centre for Brewing and Distilling 12


Unit 11: Production of spiritsOne technique used by a number of distilleries is to introducetemperature cycles to warehouses during the winter months. Forexample, when the temperature falls to say 15°C heat is turned onthrough steam pipes and the temperature raised and held forperhaps a week at 25°C. Then the heat is turned off and thewarehouse windows opened to reduce the temperature again. Suchcycles would be carried out 3 – 6 times during the winter moving thespirit into and out of the oak thereby accelerating the maturationprocess.Some distillers move casks routinely between the top and bottomhalves of the warehouse because of the high temperatures attainedin the top of the houses during summer.11.3 Canadian Whisky.11.3.1 Background.After the Second World War modern distilleries shot up in Canada,but following this boom there have been many closures so that todayonly ten distilleries remain. The distilleries are widely spread fromAlberta in the west to Nova Scotia in the east.Canadian whisky is usually assumed to be rye whisky but this ismisleading, for with the exception of one distillery in Alberta,Canadian whisky is made from a higher proportion of maize than rye.11.3.2 Process.The process for wash production broadly follows that described forAmerican whiskies, but some distilleries have replaced malt andsimply add commercial enzymes. Backset is employed and yeast issubjected to lactic souring.Most distilleries use continuous stills.Maturation tends to be carried out in bourbon casks and it mustexceed three years in casks, which are no larger than 681 litres (150gallons).Two types of whisky are produced; the lighter bodied grain whiskiesare blended with heavier bodied flavouring whiskies. The flavouringwhisky recipes are well guarded secrets and distillation of them iscarried out to retain a relatively high level of congeners.© 2001 The International Centre for Brewing and Distilling 13


Unit 11: Production of spiritsUnusually Canadian whiskies may contain up to 9.09% of flavouringadditives which may include wines and sherries, rum, bourbon andmalt whisky. The level employed is well below this defined limit.KEYPOINT: Canadian whisky can be flavoured with wines,sherry, rum, bourbon and malt whisky.11.4 Gin.11.4.1 Background.Gin is a spirit made from fermented grain or molasses, withbotanicals (herbs and spices rich in essential oils) added to giveflavour and complexity.It was invented in the early seventeenth century in Holland where itwas used as a medicine, containing juniper for the kidneys andcoriander for the stomach.Gin arrived in England as a consequence of the seventeenth centuryWars of the Netherlands when English soldiers took a liking to Dutchgin or Genever (genever is the Dutch word for juniper). By 1743 theannual consumption of gin in Britain was 70 million litres amongst apopulation of only six million. It had become the drink of the poor andexcessive drinking of gin produced serious social problems(Hogarth’s famous etching “Gin Lane” depicts such a scene). The ginof this time was sweetened with sugar and was known as “Old Tom”.By the industrial revolution of the 1830’s smart gin palaces hadbecome popular, the addition of sugar went out of fashion andLondon Dry Gin was created. Distilling companies were establishedwhose names remain associated with the drink today – Gordon,Tanqueray, Booth - and a change in drinking habits followed with ginbecoming popular as a base for mixed drinks.European Union regulations for gin require it to be “produced solelyby redistilling ethyl alcohol of agricultural origin, with an initialstrength of 96% abv, in stills traditionally used for gin in the presenceof juniper and other natural botanicals such that the juniper taste ispredominant”. It must be at least 37.5% abv.© 2001 The International Centre for Brewing and Distilling 14


Unit 11: Production of spirits11.4.2 Process.The starting point for gin is neutral spirit. This is made from grain(usually wheat or maize) or molasses, though the former is preferredfor quality reasons.KEYPOINT: Neutral spirit made from grain or molasses is thealcohol source for gin.There are three methods of producing gin from neutral spirit.1. Distillation of neutral spirit with botanicals2. Compounding a strongly flavoured distillate with neutral spirit3. Addition of flavour essences to neutral spiritHigh quality gin is produced by the first method and the cheapestversions are made with essences.For the quality process neutral spirit, which is produced at a strengthof about 96% abv is reduced to about 60% abv and redistilled with amix of botanicals in a copper pot still with lye pipe and condenser.The botanicals are either added directly into the spirit or suspendedin it in a cotton bag or wire-mesh container. Distillation takes placeslowly and a full cycle may last as long as 8 hours. The first runningscoming from the condenser are collected separately as heads untilstrength measurement and nosing indicate the required quality. Thelength of the middle cut is defined for each brand and once apredetermined strength has been reached the distillate is collectedas tails. Heads are returned to a subsequent charge but the tails aredistilled separately simply to recover alcohol. The main productstream collected will be at a strength of about 85% abv and isreduced before bottling to the range 37.5 - 47.3% abv. There is nomaturation process with gin so it can be drunk a week or so after thegrain is fed into the mash house.The compounding process requires a gin concentrate. Theconcentrate is made by adding a much greater quantity of botanicalsthan normal to the pot still and then simply blending the concentratewith neutral spirit.The third production method uses gin essences, which are preparedby blending essential oils and other extracts from botanicals. A highlyconcentrated essence can flavour neutral spirit at a dosage rate of as© 2001 The International Centre for Brewing and Distilling 15


Unit 11: Production of spiritslittle as 0.01% (such a gin must be called “compounded” ratherthan”distilled”).Dutch gin is made in a different way to British and American gin. Amash containing 30% malt and 70% unmalted cereal is fermentedand distilled with low rectification. Botanicals are then added for afurther distillation but the resultant spirit has high congener levels aswell as the botanical flavours.11.4.3 Botanicals.While gins contain a wide selection of botanicals, the essential one isjuniper with coriander and angelica next in importance.Juniper berries, from Juniperis communis, are grown for ginproduction in Central Europe. The best area is Tuscany but SouthernGermany, Hungary and Yugoslavia also produce quality crops. Theberries, which are smooth skinned and deep blue in colour, are driedand classified for gin on the basis of appearance and their extractedessential oil. The key components of the oil are pinene, myrcene,sabinene, limonene and muurolene.The second major botanical is the fruit of the herbaceous annualcoriander, Coriandrum sativum, which is cultivated in Russia andEastern Europe. The dried seeds possess a perfumed but slightlycloying odour. The main component is linalool.The dried root of angelica, Archangelica officinalis, provides a thirdimportant ingredient. This is produced in Germany and the driedroots acquire a must-like odour due to the predominance of highboiling lactones.KEYPOINT: Juniper, coriander and angelica root are the keybotanicals in gin flavouring.© 2001 The International Centre for Brewing and Distilling 16


Unit 11: Production of spiritsOther botanicals used in gin production are shown in Table 1.Liquorice rootCinnamon barkOrange peelLemon peelCassia barkCardamom seedsOrris rootCaraway seedsCallamus rootGlycyrrhiza spp.Cinnamomum zeylanicumCitrus sinensis and aurantiumCitrus lemonCinnamomum cassiaElettaria cardamomumIris pallidaCorum carviAcorus calamusTable 1. The Secondary Botanicals of Gin11.5 Vodka.11.5.1 Background.Vodka has a long history in Eastern Europe, with both Russia andPoland claiming to have invented the drink. The name stems fromthe Russian word “voda” meaning water or “woda” in Polish. The firstdocumented production of vodka dates back to the ninth century.During the Middle Ages the distilled liquor was used mainly formedicinal purposes. The mid fifteenth century saw the appearance ofpot stills in Russia and by the next century production had grown tosuch an extent that taxation was introduced. Vodka became thenational drink of Russia, Poland and Finland.The aristocracy was allowed to distill their own vodka on their estatesand many of the flavoured vodka recipes date back to these families.Cheaper vodka was made by commercial distilleries, which wereoften government owned (production became a state monopoly inRussia in 1894). After the Russian revolution a number of vodkamakers emigrated, taking their recipes with them. One of these wasPierre Smirnoff, who tried to revive his brand in Paris somewhatunsuccessfully. Then he moved to the USA and sold his recipe to anentrepreneur who opened a vodka distillery in Connecticut. By the1950’s vodka’s popularity was on the rise and it has continued togrow in world markets to the extent that it is now produced in a greatmany countries.Although there are many vodkas flavoured with ingredients like fruits,and even coffee and peppers, it is the clear neutral spirit with no© 2001 The International Centre for Brewing and Distilling 17


Unit 11: Production of spiritsdiscernible flavour, which is drunk with mixers, that has led thegrowth in demand.Vodka is defined in the European union as a “spirits drink producedby either rectifing ethyl alcohol of agricultural origin or filtering itthrough activated charcoal so that the organoleptic characteristics ofthe raw materials are selectively reduced”.11.5.2 Production.Vodka is prepared from neutral spirit which generally is derived fromgrain or molasses, like the neutral spirit used for gin. There was ahistory of making vodka from potatoes in Eastern Europe, but whilepotatoes, may still be used to a small extent, they are considered tobe an inferior source of starch for spirit production.The key processing step in converting neutral spirit into vodka ischarcoal filtration. The filtration, the purpose of which is to removeany remaining flavour compounds, is achieved by passing dilutedspirit (usually in the range 55 – 77% abv) through a series of eight totwelve cylindrical filter tanks giving a dwell time of about eight hours.One of the filters will be repacked with fresh activated charcoal eachday so the beds are constantly being replenished. A cheaper but lesseffective batch process simply steeps the spirit in tanks containingcharcoal.KEYPOINT: Charcoal filtration is an essential step in producingquality vodka, which has a clean and odourless character.The charcoal can vary between coarse granules (up to 15 mm) andpowdered types depending on whether the filtration is in continuouscolumns or batch tanks.Analytically a vodka of acceptable quality shows only traces ofpropanol and ethyl acetate, with all other congeners undetectable.After filtration the spirit requires further dilution before bottling. Thequality of water used here, and prior to filtration, is important as it isessential that it is clean and odourless. Most water used isdemineralised though this is largely to avoid the appearance of a filmof salts around the bottle or glass, which may appear as the alcoholevaporates.There is no maturation required, so like gin the period betweenprocessing cereals and drinking can be very short.© 2001 The International Centre for Brewing and Distilling 18


Unit 11: Production of spirits11.6 Rum.11.6.1 General.The raw material for rum is sugar cane products. Rum can be a lightneutral spirit produced by continuous distillation or it can be a heavilyflavoured dark product produced in a pot still. Many rums are a blendof the two types.Rum production is largely centred in the Caribbean islands, wheresugar cane is the major crop. Bacardi rum, which originated in Cuba,is the biggest selling brand of all the spirits.11.6.2 Production.The feedstock for rum production is either sugar cane juice ormolasses.Cane juice is obtained by pressing or crushing the cane, but it hastwo disadvantages. Firstly it has a relatively low sugar content andcan only produce a fermented liquid of 6 – 8% abv. Secondly it isvery susceptible to spontaneous fermentation caused by the heavycontamination of yeasts and bacteria which it bears. The latterproblem means that it can only be used during the harvesting periodand the distillery must be close to the cane mill.Molasses exists in a number of forms, and it is the so-called“blackstrap” molasses which is the type used for rum. In theproduction of cane sugar the juice is heated, filtered, treated withlime to remove fibres and sludge, and then concentrated byevaporation. Crystallisation then occurs and the sugar crystals areseparated by centrifugation; the cycle is repeated twice and theresidue is blackstrap molasses. It is essentially a waste material fromsucrose production and is a viscous, brown liquid, which contains 45– 60% fermentable sugars by weight.For heavily flavoured rums spontaneous fermentation can be usedthough, as might be expected, the results are somewhatunpredictable. However the bacterial contamination is responsible forsome of the important congeners and this has to be taken intoaccount when employing controlled fermentation conditions. For suchfermentations a pure strain of Saccharomyces cerevisiae needs to besupplemented with a pure culture of Clostridium saccharobutyricum.In light rum fermentations only yeast is used and antibiotics aresometimes added to eliminate bacterial contamination.© 2001 The International Centre for Brewing and Distilling 19


Unit 11: Production of spiritsThe distillation of heavy rum is a batch operation and in its simplestform uses a single pot still, with the first distillate being collected andthen returned for a second distillation. Cuts are taken to controlcongener levels.Alternatively there may be two, or three, pot stills interconnected toavoid having to transfer distillate back into a single still. Theefficiency of the pot still in removing congeners can be improved byincluding five or six bubble cap trays between the pot and the vapourpipe and including a condenser above the trays to provide reflux.This arrangement is shown in Figure 2.Figure 2. Pot still with bubble cap tray system.The continuous distillation used for light rums is usually a two columnsystem, with a stripper and rectifier. If a very light and less flavoured© 2001 The International Centre for Brewing and Distilling 20


Unit 11: Production of spiritsrum is required then an extractive distillation column and a rectifiercan be added in a process which begins to resemble that for neutralspirit.KEYPOINT: Heavy rums are distilled in pot stills; light rums aredistilled in two column continuous stills.Combinations of batch and continuous plants are also used.Rum is matured in either new oak or bourbon casks. Light rumsrequire little aging and may be acceptable after a few weeks; indeeda few of the modern light rums are not matured at all. The heavyrums on the other hand may be matured for five years or so. Ofcourse the temperature in the tropics means that the maturationprocess is accelerated.11.7 Brandy.11.7.1 General.Brandy is produced from grapes and, although French brandies arethose which are most sought after, brandies are produced in manyother wine growing countries. French brandy falls into three classes;cognac, armagnac and eau de vie. Cognac and armagnac aredefined by their areas of production; cognac comes from theCharente and Charente Maritime in the centre of which lies the townof Cognac and armagnac from certain parts of Gers near the town ofCondom.Eau de vie is quite different. It is made from fruits such as pears(Poire William), raspberries (framboise), cherries (kirsch) and plums(slivovitz) etc. It is lightly distilled for maximum flavour and agingusually takes place in glass or pottery so there is no colour pick up.11.7.2 Production of Cognac and Armagnac.Grapes (the varieties are specified) are fermented immediately afterharvest and as soon as wine is available the distillation is carried out.For cognac only direct fired pot stills are used and these are small(less than 3000 litres). The wine is distilled until the vapour contains© 2001 The International Centre for Brewing and Distilling 21


Unit 11: Production of spiritsnegligible quantities of alcohol which may take 8 hours. The maindistillate called “brouillis” will contain 24 – 32% abv. A tails fraction iscollected and returned to the pot still with the next batch of wine. Thedistillates from three batches are combined and then distilled for asecond time.This second distillation is longer taking maybe 14 hours and thedistillate from it is split into three sections, heads, tails and the middlecut which would be in the range of 58 – 60% abv.The new spirit is racked into new wood for a period of 8 – 12 monthsand then transferred to an older cask. The casks of 275 – 350 litresare made from oak from the nearby forests of Limousin or Troncais.Cognac is usually at its best after 15 to 20 years in the wood. It isblended before bottling and the strength is reduced in a number ofsteps.Armagnac differs in style from cognac, a result of differences inclimate, distillation and wood. Armagnac may be made either in potstills, like cognac, or in a special continuous still, as shown in Figure3, with 5 to 15 trays built into a wide neck. The wine is distilled to givea relatively low spirit strength of about 53% abv with quite highcongener levels.KEYPOINT: Cognac and armagnac are distilled in small (less than3000 litres) direct fired pot stills. Armagnac can also be madecontinuously in a pot still fitted with trays.Armagnac is matured in “black oak” or Gascon casks, which addmore flavour than the white Limousin oak. It matures much quickerthan cognac and at eight years is considered well aged.© 2001 The International Centre for Brewing and Distilling 22


Unit 11: Production of spiritsFigure 3. A Continuous Armagnac StillA: head of wine; B: cooler; C: wine heater; D: head condenser; E: winearrival; F: column; G: boilers; H: head column coil; I: swan neck; J: coil; K:drawing and recycling of tailings; L: alcohol meter holder; M: furnace.© 2001 The International Centre for Brewing and Distilling 23


Unit 11: Production of spirits11.8 SUMMARY OF KEY POINTS1. While Irish whiskies are generally characterised by tripledistillation and unpeated malt, there are exceptions to both ofthese distinctive features.2. Irish pot still whiskey is made from a mash of malt and unmaltedbarley.3. Bourbon must contain 51% of maize and be aged for at leasttwo years in new charred oak casks at a strength below 62.5%abv.4. Most American distilleries maintain their own yeast strains.5. American whiskies are almost exclusively produced bycontinuous distillation in a single column followed by a furtherdistillation in a doubler.6. Canadian whisky can be flavoured with wines, sherry, rum,bourbon and malt whisky.7. Neutral spirit made from grain or molasses is the alcohol sourcefor gin.8. Juniper, coriander and angelica root are the key botanicals ingin flavouring.9. Charcoal filtration is an essential step in producing qualityvodka, which has a clean and odourless character.10. Heavy rums are distilled in pot stills; light rums are distilled intwo column continuous stills.11. Cognac and armagnac are distilled in small (less than 3000litres) direct fired pot stills. Armagnac can also be madecontinuously in a pot still fitted with trays.© 2001 The International Centre for Brewing and Distilling 24


Unit 11: Production of spirits11.9 SELF ASSESSMENT QUESTIONSWell I expect you could do with a drink after all that! What will it be awhisky, a whiskey, a bourbon, a gin, a vodka, a rum, or a brandy?But just before you pour it out why don’t you prove you have earnedit by answering a few questions on the pages you have just read.1. What are the main process parameters which characterise Irishpot still whiskey?2. What is sour mash?3. What is a doubler?4. What is the type of spirit used in the production of gin and fromwhich starch sources is it usually derived?5. What are the two most important botanicals used to flavour gin?List a further four which may be used.6. What is the shortest time that can elapse between cooking wheatto make neutral spirit and drinking the vodka produced from it?7. Why would a rum distillery be close to a sugar cane factory?8. What are the differences in the distillation and maturation ofcognac and armagnac?© 2001 The International Centre for Brewing and Distilling 25


Unit 11: Production of spirits11.10 SELF ASSESSMENT ANSWERSNow let’s see if you have earned that drink!1. What are the main process parameters which characterise Irishpot still whiskey?The mash is a mixed grist of malt and unmalted barley, with theunmalted proportion as high as 60%. The malt is usually unpeatedand the wash is usually subjected to triple distillation.2. What is sour mash?Sour mash, or backsetting, is the re-use of spent wash in the mashmix. The spent wash is centrifuged to remove solids and maintainedat a temperature high enough to guarantee sterility before use. Itlowers the pH of the wort and offers energy and effluent savings.3. What is a doubler?A doubler is a distillation kettle, like a pot still, which is runcontinuously with a fixed level of liquid heated by steam coils. It isused as a secondary distillation following the primary column stilldistillation in many American distilleries, raising the alcohol level fromabout 55% to 70% abv.4. What is the type of spirit used in the production of gin and fromwhich starch sources is it usually derived?Neutral spirit made from wheat, maize, rye or molasses5. What are the two most important botanicals used to flavour gin?List a further four which may be used.Juniper berries and coriander seeds are the two most importantbotanicals in gin production. Others are angelica, liquorice,cinnamon, orange and lemon peel, cassia, cardamom, orris,caraway, and callamus.6. What is the shortest time that can elapse between cooking wheatto make neutral spirit and drinking the vodka produced from it?The shortest time would be about six and a half days. Cooking,mashing and fermenting say 5 days; distilling and filtration say 12hours; reduction and bottling say one day.© 2001 The International Centre for Brewing and Distilling 26


Unit 11: Production of spirits7. Why would a rum distillery be close to a sugar cane factory?A rum distillery would be close to a cane sugar factory because thecane juice cannot be stored for any length of time as it is susceptibleto spontaneous fermentation.8. What are the differences in the distillation and maturation ofcognac and armagnac?Cognac is distilled twice to give spirit of 58 – 60% abv. Armagnaccan be distilled continuously in a pot still fitted with trays. A loweralcohol level of about 53% abv is produced with higher congenerlevels. Good cognac is matured in Limousin oak and transferred froma new cask to an old one after 8 – 12 months. Cognac is at its bestafter 15 to 20 years. Armagnac is well aged after 8 years in Gasconoak casks.© 2001 The International Centre for Brewing and Distilling 27

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