Introduction

The Process in general

Whiskey is made by:

• Crushing grains (barley, corn, rye, wheat) to create the grist (almost always inc. malted barley - steeped in water to trigger germination).
• Adding grist to warm/hot/boiling water and mixing (3 or 4 separate washes) to create the mash (mashing extracts soluble sugars from the grain).
• Liquid (wort) is drained off (not the boiling one - that starts the next round) and transferred to washbacks. Grain residue is used for animal feed.
• Adding yeast for fermentation. Yeast converts sugars in the wort into alcohol.
• Fermented wort ('wash' or 'distiller's beer') is boiled in a still (distillation). Alcohol is driven off, as vapour, leaving water. Vapour is collected and cooled back into a liquid spirit. 2nd distillation separte undrinkable alcohol (foreshots and feints) from the drinkable.
• Aging the resulting spirit in wooden barrels.

Barley is important to distilling due to its high levels of starch. Malted barley has the enzymes essential to convert starch into fermentable sugars during mashing. 1968 saw introduction to Scotland of 'Golden Promise' variety of barley. Now mainly superseeded by other varieties such as 'Optic' since the 1990s.

Fermentation also produces congeners - acids, aldehydes, esters, higher alcohols. Small in quantity but affect taste and quality of the spirit.

Need good water supply. Largest volume of water is used in the condensers. Cold water passes through and cools the spirit vapours, water temperature then rises therefore guidelines cover temperature and flow rate for water returning to the watercourse. Water first used to steep the grain then mash. Water in these 2 steps is 'process water'.

Calcium affects rate of fermentation (action of yeast) and therefore the flavours created during that stage. Soft water - low calcium - enables yeast to make a strong start. Calcium lowers the pH, increases water hardness and yeast flocculation and might reduce magnesium, making the flavour less sour.

During distillation the proportion of alcohol to water changes in the stills. Alcoholic strength is reduced for ageing by diluting with water (=reduction water) to stand strength of 63.5 in Scotland and 55-60 in Kentuky. Water content influences which flavour compounds are extracted from the oak cask. Higher filling-strength extracts more alcohol soluble compounds and a lower strenth extracts more water soluble compounds.

Deionised/neutral water is used to reduce strength of mature spirit. Untreated water may risk change in levels of calcium and precipitate white crystals which creates white haze on the bottle.

Taller, slimmer stills encourage more reflux, as temperatures are cooler at the top and lighter flavours continue onto the condenser. (Reflux = richer flavours have a higher boiling point, condense from vapour back into liquid before leaving the still, so are redistilled again.)

Rate of evaporation from the cask is important.

• Scotland - average rate is 2% per annum (water and alcohol) so decreasing strength of alcohol.
• Warmer climate, eg: Kentuky, rate is 3-5%. Barrels on upper floors get warmer and lose more water than alcohol so alcoholic strength rises during ageing.
• This affects the alcohol or water soluble compounds being extracted from the cask - the stronger the spirit the more alcohol soluble compunds are extracted.
• Higher alcohol strength can slow down oxidation (changes from exposure to air). Changes encourage development of floral and fruit notes in flavour. Humidity encourages oxidation.

Triple distillation, used in Ireland, gives lighter, more fruity, floral and spicy character to whiskey.

Single Grain Whisky is often used in blended whisky to tone down the wilder flavours of Single Malt and Pot Still spice.

Malting

Accounts for 2/3 of the cost of production. Malting breaks down the starch in barley through steeping, germination and kilning.

Steeping:

• Barley is soaked in large containers (steeps) to start germination.
• 2 or 3 separate batches of water are used (24-36 hours), with O2 pumped into the steeps between each batch = 'air-rests' and 'wet time'. More O2 increases rate water is absorbed.
• May or may not contribute to the final flavour.

Germination:

• Grains are spread across large, stone or concrete malting floors.
• For consistent germination the barley is turned / aerated using shovel, plough or rotivator.
• Takes 5-9 days depending on temp.
• Stops when the rootlets are about 3/4 the grains length = green malt

Kilning:

• Grain spread across a perforated floor at uniform depth to be dried by heat rising from below.
• At this stage the malt can be peated with smoke from burning peat. Peating levels measures as parts per mill. Light peat is c. 2 -10 ppm and heavy peat is 50-60 ppm.
• Floor maltings take up to 12 days with a lower yeild than commercial maltings (c.7 days).
• Need to monitor conditions continuously to maintain consistency. Eg: moisture in peat can vary so might add wet peat to create smoke or dry peat to create heat.
• Kilning stops growth within the grain that would otherwise consume the starch inside - starch is needed to form alcohol.
• At commercial maltings burning fuel to creat direct heat has been replaced by indirect heating - air heated by being conducted through pipes which are heated by a water boiler.

Casks and Ageing

While maturing in a cask reactions between the liquid and the wood create flavours eg: vanilla from oak. Britain has a tradional of sherry trade with Spain. The ex sherry casts were used for whiskey. In 1960s Macallan experimented with different sherry casks and favoured butts that contained dry oloroso sherry, for maturation of approx. 2 years. Imparts sultana, apricot and orange flavour. 1980s realised the sherry was less influencial than the wood itself and Macallan changed to constructing own barrels using Quercus robur oak from NW Spain.

Some feel sherry casks have too strong an influcence on the whiskey during first fill. Second-fill casks are more favoured for balance. By third fill will no longer be described as a sherry cask.

American oak (vanilla, cream and coconut flavours) are now used having contained sherry or bourbon. Bourbon barrels thought to round out a malt without masking the house quaility. Glenmorangie age their principle product in bourbon barrels for 10 years. They use Quercus alba oak from the Ozarks, Missouri, USA. They air dry the wood, not kiln dried. Are used to mature Jack Daniel's for one vintage before being sent to Scotland.

In Scotland must mature for minimum 3 years and in Kentucky it's 2 years.

Scotland has two types ageing warehouse:

• Dunnage - Traditional. Low level, stone or brick building thick walls,slate roof, earth floor. Stable temps. Casks usually stacked 3 high so little difference between temps at top and bottom. Usual capacity is about several hundred casks.
• Racked - Popular in USA, Canada, Japan, Ireland. Multi-storey system of steel racks, holding up to 20,000 casks. Tin roof, thin, cladded walls so varied temps in the year. Kentucky has also open-rack warehouses, stacking up to 24 high, on exposed hillsides with tin roofs.

Microclimates in warehouses affect strength and flavour but this tends to character, not quality.

Natural Environment

Rye prefers cooler climates and moderate rain, as in Dakota, Wisconsin and Minnesota and Canandian prairie. Rye adds spicyness to flavour and fruit and dryness to the palate.

Corn grows well in Iowa, Kentuky, Indiana, Illinois and Ohio, where there is high rainfall and the crop can mature before temperature gets too hot.

Barley better suited to Scotland's mild climate, and long summer hours. Too much sun and too little rain can result in grain ripening prematurely. Global warming has bought the harvest forward from September to August. Barley contributes depth and softness with a biscuity sweetness/malted cereal notes.

'Winter' wheat is preferred - planted autumn and harvested late next summer - as it has high starch and low protein.('Spring' wheat is planted spring and harvested next autumn.)

More sunshine increases photosynthesis and raises levels of starch in barley seed results in higher yield of alcohol. Although grapes reflect the weather patterns more than barley. Character of vintage malts are reflected more by how the malt has been matured, type of cask used and type of ageing warehouse.

Water temperature is important. Colder water means grains must be steeped longer to take up enough water. Also affects end of distillation if worm tubs are used. Water flowing through the tub cools the pipes, which will condense vapours flowing through. If the water in summer is too warm then must allow more time for this part of process (to maintain consistency in the character of the spirit).

Geology affects the flavours:

• Soft rock leaches mineral so produces hard water, with higher level of dissolved mineral salts - calcium, magnesium, iron and zinc.
• Limestone (soft rock) has high level calcium but not iron. Limestone areas, eg: Kentuky, have cave systems. In bourbon industry the caves act as aquifiers, to provide supply of water, and porous rock filters the water for mashing. Kentuky water is rich in calcium.
• Grampians have granite (hard rock so soft water); Most of Scotland is soft water; Sutherland has sandstone (soft rock); Cuillins of Skye and Northern Ireland have basalt (hard from volcanic action).
• Lousiville & Lexington, USA, have limestone.

Tradition has it that water flowing through heather moors (for example) picks up the floral characteristic along the way and influences steeping and mashing. This is hard to quantify. Floral flavours are prodcued in fermentation, distillation and oak ageing (oxidation process within). Floral more in malts matured in bourbon casks than sherry casks. Marine aromas (sea air, seaweed, iodine, brine) a feature of peated malts. No definative explanation for how the coastal environment affects the final whiskey. Although steeping the grain in water that has flowed through peat (for example) may impart flavour, the kiln process (drying the grain) has more influence.

News: Research shows terroir in whisky does exist. A study led by Oregon State University and Waterford Distillery has concluded terroir does have an impact on the flavour of whisky. Feb 2021.

Raw Materials - Scottish whisky class

Scot. 2009 regulations cover aspects of ingredients and the process.

SMW can only include water, malted barley and yeast.

Grain whisky includes water, yeast, malted barley and other unmalted cereals (maize, whet, rye). Grain spirit produced either by batch or continuous distillation. Where 100% malt is used in continuous distillation the product must be called 'Scotch Grain Whisky'.

In unmalted cereals malted barley is not used as the source of both starch and enzymes in the production of grain spirit. Malted barley is only the enzyme provider. Starch is provided by the unmalted cereals, which is then broken dowwn into sugars by the enzymes from the malted barley. It is illegal to use any other source of enzyme. In the past 'green malt' (germinated barley prior to the kilning process) was used in the process. It has an increased enzyme potential than kilned malt.

In production of malted barley, peat can be used in the drying process - smoke adds distinctive flavour.

Maturation- 'new make spirit' must be matured min 3 years in oak casks, not greater than 700 litres in size; must take place in Scotland; alcohol to be distilled no less than 94.8%.

Malting barley:

• Any can be used but specific bred varieties with appropriate agronomic (how it grows on a farm) and malting characteristics are grown for distilling.
• Must be rich in starch and enzyme potential. Enzymes beak startch down in to sugars - then sugar is metabolized by the yeast to create alcohol.
• Can be grown anywhere but most barley used in Scotland is from UK. Barley can be rejected at harvest time is not suitable.
• Barley is dried then malted. Now normally done at dedicated malting plants. Some ditillery still have a malting floor and malt on site eg: Balvenie, Bowmore, Highland Park and Springbank.

Water:

• Distillation needs consistent supplu of fresh, clean water and is why distilleries are historically located near burn or loch.
• Distill. water is exempt from water potability regulations as it is later subjected to other processes.
• Can be filtered to remove debris or treated with UV light to deal with microbial contamination.
• Four uses in distillation (also used in malting): 1) Mashing - hot water added to grist to produce mash. 2) Cooling - condense alcohol vapour back into liquid. 3) Dilution - pure water added to make 'new make spirit'. 4) Washiing - to clean equipment, is treated as effluent.

Yeast:

• Unicellular organism and under anaerobic/no oxygen conditions can metabolise/use sugars to create alcohol = fermentation.
• Yeast + sugar = ethanol + heat + CO2 + Congeners (flavour compounds)
• Now produced in specialist plants and delivered to distillery either dried, in a cake or most often in slurry (thick liquid called creamed yeast).

Peat:

• Used in making some types of malt for pot still or batch distillation where it imparts a medicinal or smoke aroma to the final spirit.
• Partially decomposed plant matter found in cool, wet conditions.
• When burnt creates 'peat reek' - smoke contains phenolic compounds producing the aroma.
• During kilning peat is burnt to produce pet reek that deposits the phenolic compounds onto the husk of the malt.

Production - Scottish whisky class

Malting - Milling - Mashing - Fermentation - Distillation (= new make spirit) - Maturation - Scotch whiskey.

Barley is processed in 12 stages: Harvest (+tested) - Drying - Analysis - Steeping - Germination - Kilning - Storage and analysis - Delivery to distillery - Milling - Mashing - Fermentation - Wash.

Malting process includes Steeping - Germination - Kilning stages. Mostly done using 'drum' maltings, with large drum turned constantly.

In UK barley is too wet to store directly so it is dried first.

Tested after the harvest for a number of parameters. Automated barley sampler allows for sampling from lorry at different locations, from the control room. Samples sent to control rool or the lab. to be mixed to provide a good sample. Looking at:

• Moisture - needs to be within contract specification and that it hasn't been dried at the farm.
• Nitrogen - for protein content, which is inversely related to spirit yeild ie: increased not. = decreased potential spirit yield.
• Screening - grain size, need same size for even malting.
• Germination - to see if it is alive and will grow well.

Only after testing is barley purchased for malting. Before malting often has to be stored and for this it must be dried to a safe storage level. Dried to under 12% moisture and kept under 15 degrees C, can be stored for years. Dried by blowing warm air through the grain.

Barley structure: endosperm is at the centre (starch for initial growth); husk/bran is the outer rim (for protection); embryo/germ is at one end (living part); micropyle at the tip of the embyro (small hole for water to enter). image.

Steeping:

• Barley added to water to allow grain to soak up moisture and start germination.
• Machinery haas temp. probes and chutes and overflow drains - dust and debris is drained from the top of the steep.
• Multiple steeping used to allow desired moisture to be reached quicker. Ends up with moisture level c. 45%
• Then germ. (=green malt) is stopped by kilning.

Kilning:

• Stops germ. by blowing hot air through grain bed - natural circulation is created by the pagoda roof.
• Peat can be used here for flavour. Phenols in peat can attach to the wet surface of the grain so only burnt at the start of this stage.
• Green malt is dried to 5% moisture to allow for storage. Now = malt or malted barley.

Milling:

• 1st process now done in most distilleries.
• Mill crushes malt into grist = 70% grits, 20% husk, 10% flour
• Helps achieve max. yield of alcohol.
• Grist analysis is carried out to determine % of the fractions.

Mashing:

• Starch and enzymes created in malting are used. Enz. break starch down into simple sugars to be used by yeast in ferm.
• Grist mixed with hot water (about 63.5 degrees); starts in mashing machine in the mash tun; temp. is controlled to allow for max. conversion.
• Sugar is disolved to create 'wort'; then wort is drained from the tun and collected in tank called 'under back'.
• Trad. mash tun used rakes and paddles on arms which rotated to mix the mash. Not as efficient as modern equipment which slices through mash in a more controlled manner.
• In mash tun another charge of water is added - sparging. Hotter at 80 degrees to dissolve remaining starch and sygars; drained through the underback and pumped into the 'washback'.
• Another water charge at 85 degrees dissolves what's left; drained and used as first chrage for next batch of grist.
• Wort from underback can be over 60 degrees which is too hot for yeast. Also need more starh and long chain sugars to be reduced by the enzymes in the washback but the high temp destroy these. Wort goes through a plate heat exchanger (wort cooler) and temp decreases to 16-18 degrees.
• Lauter - a mashtun design. Speedier draining than trad. equipment. Raises and lowers the lauter arms as they slowly rotate in the mash.
• Mash tun residue = 'draft' and is used for cattle food or burnt in biomass boiler.

Fermentation:

• Ethanol/alcohol is produced - natural process, yeast uses sugar made in mashing.
• In this process yeast produces heat, ethanol, CO2, congeners
• Wort is cooled and pumped back into washback and yeast is added. Now mostly added inline as a liquid.
• Washback temp now increased to 30 degrees. No temp control in most distilleries (unlike brewing)

Wash:

• Farm. takes 48 hours, yeast dies off.
• Can ferment for longer to create diff flavour congeners by a secondary ferm from bacteria and wild yeasts.
• Liquid is now a weak beer called 'wash', 8-10% alcohol by vol.

Batch distillation - Scottish whisky class

Liquids are separated based on different boiling and condensing properties. Trying to separate the ethanol and flavour congeners from the water in the wash.

Image of basic process.

Another image. And another.

For SMW distillation is done in a pot still, vapours condense to liquid using water cooled condensers. 1st distill is in the wash still and 2nd is in the spirit still. Distillates (liquid collected after distill.) pass through the spirit safe and are monitored for quality. Measured for density/gravity and temp.. The alcohol vol. is then calculated.

Three cuts from the spirit still 1) heads/foreshots which go to the Feints Receiver 2) middle/heart/spirit go to the Intermediate Spirit Receiver 3) tails/feints go to the Feints receiver.

Pot stills

Origins in Ancient Egypt.

Copper is used as an effective heat conducter; maliable to shape; good catalyst (speeds up reactions); reacts with compounds in gaseous state, notably removes some sulphur containing compounds in the wash.

3 sections 1) body/pot where the liquid is boiled 2) column/neck up which the vapours rise 3) lyne arm/lye pipe where the vapours leave to the condenser.

Boil pot/Ogee - onion style bulge at foot; purifies by trapping heavy impurities and returning them for further boiling; normally on a spirit still but can be on the wash still.

Some distilleries use a 'purifier' as an adjunct to the condenser to add extra reflux or purification.

Still is heated to boil liquid and vapourise the alcohol. Originally heated by direct heat or coal firing but now use internal steam coils or external heating. A safety valuve ensures the still doesn't collapse.

Lyne arm

Joins the still to the condenser system. The slop is critical on reflux action - the process where vapour gradually condenses, contributing to the character of the New Make Spirit (oily & heavy or frity & floral). Once the vapour becomes liquid, flows through the tail pipe into the spirit safe. If there is no safe , as in some modern set ups, then flows into the collecting tank.

Process

1) Wash pumped (maybe via wash charger) into wash still (larger than spirit still). Charger stores wash to ensure constant feed to the still.

2) Liquid is heated and ethanol and other compounds are vapourised.

3) Distillate goes down lyne arm and through the condenser to become liquid again. Is collected and called 'low wines' = c.25% alcoh by vol.

4) Remaining residue from wash still is 'spent wash' and can be used in cattle feed. This first distillation is normally 100%/total.

5) Scotland does a second distillation. Low wines are distilled again and when returned to the spirit safe is normally 70-75% ABV. Residue from spirit safe = spent lees, sent to effluent plant for disposal.

Now there are 3 parts a) foreshots/head b) spirit/heart c) feints/tails

a) becomes spirit after c.20 mins. a) + c) + low wine from wash still are recycled into the next spirit charge.

b) is the New Make Spirit and goes on to mature in casks.

Only about 10% vol. of original wash remains at the end of the process.

Condensers

Two types used in Scotland - 'Worm' and 'Shell & Tube'.

Worm:

• Almost same as illicit stills
• Copper pipe coiled around edge of large vat of cold water.
• NMS condensed with a worm tube generally produces a more sulphury/meaty flavour.

Shell & Tube:

• Modern and more efficient.
• Give better copper contact so decreases the sulphur flavour.
• Cold water runs through centre of shell via thin tubes. Vapour in the shell then condenses.

Spirit safe - an operator monitors the alcoh level by using a hydrometer and themometer. Operator can direct the flow from spirit safe to either ISR or foreshots & feints receiver.

Image of triple distillation safe.

Intermediate Spirit Receiver.

Cut points = where a distillery changes from foreshots to spirit (normally down by time eg: 20 ins) & from spirit to feints (normally use alco strngth as indicator to change eg 62-65%). Master distiller will decide the cut points, which impact significantly on character of final NMS. eg: phenol character can be changed depending on cut point from spirit to feints.

Reflux

Quality (character, aroma, flavour) of NMS depends on various factors, esp. the reflux process. It's the physical process in the still during distill. Compounds cool as they rise, if condenses then will stay in the still and drop back to be boiled again - this is reflux.

Is progressive purifying, refining action which develops sophistication of the distillate, eliminates impurities and baser elements.

How to control reflux? More reflux = lighter NMS; Less reflux = heavier NMS.

Feature	More Reflux	Less Reflux
Size of still	taller	shorter
Shape of still	ogees & bumps	plain & straight
Slope of lyne arm	up from still head	down from still head
Vol. of original liquid	smaller charge	larger charge
Speed of still	slower	faster
Purifiers	used	not used

Things that affect reflux:

• Anything that cools vapour will enhance reflux eg: ogees, bumps, at col. base and boil pots.
• Still size varies as does ratio in size between wash and spirit stills, therefore as does the amount of liquid that makes a 'charge' /fill. Variations alter the travel distance of gases from liquid to condenser eg: Less charge = travel distance is more = enhances reflux. More charge = less travel distance = less reflux.
• Tall neck = more reflux and more copper contact = light and floral character.
• Short neck = less reflux = oily , heavy character.
• Ascending lyne arm = more reflux = light and floral. Vapour condenses into liquid in the pipe so flows back down to boil again.
• Decending lyne arm = less reflux = heavier. Any liquid flows into condenser and tailpipe therefore less reflux.
• Straight lyne arm does not affect reflux.
• Ogee = more reflux = light and floral.

Maturation - Scottish whisky class

Scotch Whisky regs say malt and grain NMS must be matured in oak casks for a min 3 years.

Acorn has 1 seed which takes 6-18 mths to mature; oak wood prevents leaks but also allows liquid to breathe; has many soluble compounds which impart aroma/flavour/colour into the spirit at different stages of maturation.

For some spirit the most important flavour uptake is during the initial dwell time following filling. For otgers it takes longer to develop during the oxidisation process.

2 oak types in Scot. industry:

• Quercus alba - American oak; used for casks with bourbon indutry origin; more popular in Scotland.
• Quercus robus - Euro. oak; origins in Euro wine industry; tend to be Oloroso sherry butts.

Ex-bourbon:

• ASB = American Standard Barrels = air or kiln dried, charred on inside and filled with single fill of bourbon.
• By law bourbon barrels must be charred and can't be reused in the USA.
• UK doesn't make casks so must import them.
• Full bourbon casks usually sent to Scotland for bottling.

Common cask sizes - ASB = 200 litres / Hogshead = 250 litres / Butt = 500 litres; must be under 700 litres to be legal in Scotland.

Casks can be virgin (new wood used first time with NMS) or used for another liquid (often bourbon or sherry - with a change in law can now use others inc. ex-tequila or calvados).

Secondary maturation - Most common refill casks are ex-bour or ex-wine; if ex-bour is used for NMS this is classes as '1st fill'and if it is used again for another batch of NMS it is classed as '2nd fill'.

Cask finishing - other cask types are used when a spirit is matured in a typical cask then decanted into another type (often port/rum/red or white wine) for up to 24 mths.

Cask regeneration

Involves decharring and recharring.

Once a cask is used 3 or 4 times the rate of maturation slow, there is a decrease in the uptake of flavour compounds. Extractive compounds have been removed from the active wood layer by successive fillings.

Decharring - ends of cask are removed; thin layers of wood are shaved off; wood is heated treated (toasted or charred); ends replace to create a new barrel. This allows for a new active layer with new set of compounds to be extracted; if charred there is also a layer of charcoal.

Flavour compounds of oak

Over 25 different oak derived flabvour compounds. Many are soluable in water or ethanol and as liquid matures it interacts with the wood molecular structure (called lignin).

Compounds can be extracted via lignin heat degradation, where the inside of the cask is toasted or charred and this breaks down the lignin into acids/sugars/aldehydes/vanillins.

Some of the more influential compounds are lactones, vanillins and tannins.

• Lignin infuence production of vanilla; increase in blended complexity; colour; promotion of oxidisation products.
• Oak tannins influence colour; promotion of oxidisation products; production astringency; removal of off-notes (rubbery).
• Char layer influcences removal of off notes; burnt wood flavour.

Maturation in the cask

Reactions can be extractive or oxidative and both are required.

Extractive - whisky takes up the available oak degradation compound formed in cask manufacture; these derive from oak polymers = cellulose, hemicelluloses, lignin, tannin and char layer; pyrolysis process occurs during cask manufacture to varying degrees.

Charred layer removes some aromas eg: sulphur compounds which may form in distillation, particularly where worm tube condensers were used or distillation was run too fast.

Main congeners from char layer are arabinose, xylose, furfurals (from hemicelluloses), vanillin, vanilic acid, syringe ealdhyde (from lignin), ellagitannins (from oak tannins) and oak lactones (from oak lipids).

Cask drivin oxidisation results in reactions in which ethanol, organic acids and aldehydes react to form further compounds.

Various ester and organic acides in NMS also react, so original levels in NMS will change during maturation. Their relative concentrations in the ethyl alcohol change as alcohol is lost in the 'Angel's Share' phenomenon.

Angel's Share:

• Proportion of ethanol and water evaporates and turn to gas inside the wood and lost to the atosphere.
• In damp warehouses (eg: Scotland) liquid is mainly retained and strength is decreased by lose of alcohol. Evap 1-2% vol.per year. Note that temp at Highland coast vs Speyside can vary by 10 degrees.
• In hot summers (eg: Kentucky) alcohol strength increases as liquid is lost. Evap 4-10% vol. per year. In India up to 12%..
• Quantity, rate of loss andmaturation benefits depend on warehouse temp, humidity, location and time in years.
• Climate effect maturation. Humidity affects relative rate at which ethanol is lost compared to water.

Condition	Result
Increased humidity	More alcohol lost than water, ABV less over time
Decreased humidity	More water lost than alcohol, ABV more over time
Increased temperature	More ethanol and water lost
Decreased temperature	Less ethanol and water lost

Ways casks influence whisky flavour

Alcohal strength:

• Filling strength is vital (alco. in NMS when enters cask). Some compounds (eg: lactones) more soluble in increased alco. concentration, so influence more when filling strength is greater.
• Opp. true for compounds more soluble in decreased alco. concentration.
• Certain compounds are extracted by the water phas and other in the ethanol phase.

Type of Wood:

• Different species of oak have differnt proportions of extractive compounds so affect flavour profile.
• eg: cis-lactone produces a cocomut aroma/flavour ad more prominent in American oak than Euro.

Secondary maturation:

• Ex-wine casks tend to deliver more complex extractive compounds than bourbon.
• Glenmorangie Co. pioneered cask finishing in the 1980s where ex-bourbon cask whisky was finished in an ex-wime cask (sherry/prt/maderia/chardonnay).
• eg: light red colour and chocolate flavour come from port cask.

Virgin or refill cask:

• Virgin cask will impart extractives quicker than a refill; First fill will impart more than second.
• Quantity of extactive compounds remaining in the wood is important.
• Virgin or new oak casks can have too high levels of extractives for scotch so some distillers use them only for grain whisky, after some years can then be used for maturing malt whisky.

Warehousing systems

Tradtional/Dunnage:

• Traditionally all were dunnage and beside the distillery.
• Stone walls and sand floors; casks stored on wooden rails, 2 or 3 high
• Atmosphere relatively constant so ideal for maturation.

Racked:

• Concrete and metal construction; drier/less humidity.
• Metal rails, 10 or 12 casks high.
• To ensure even atmosphere condtions casks can be rotated from warm top levels to cooler lower levels. Some Scot. distilleries notice 10 degrees difference so must monitor.
• More cost effective.

Palletised:

• Casks placed on end, on pallets and sotred together.
• Effective use of space.
• May affect flavour and quality as surface area of top end loses contact with the cask as it is set upright.

Bottling - Scottish whisky class

Mainly automated and most distillers send casks off site to a bottling facility.

Cask to vat

Whisky is transferred from cask to vat/tank in the digorging unit.

First goes through filtration to remove solids such as char or small pieces of cask.

Can be left in the vat to 'marry' (gives time to homogenise ensuring no layering of strength or falvouring) or straight into the process.

ABV reduction

Strength is reduced prior to bottling, unless it's a 'cask strength' product. Scotch Whisk Regs have a min of 40% ABV legally.

Done with deionised water.

Caramel colouring can be added at this stage. Usually done to ensure colour consistency not to add colour.

Chill filtration

May or may not occur.

When SMW is exported it could be exposed to low temps. In long, sub-zero temp it turns cloudy and can form deposits of white flakes = flocculation / chill haze.

Is reverible but clear whisky is seen as better and it is a problem if you have to recall a product or bottle at an increased strength (this resists the process).

Some whisky (esp. cask strength) can cloud when water or ice is added. This is normal. Due to long chain fatty acids coming out of suspension die to alterations in alcohol strength or a decreased temp. These compounds/molecules are usually flavourful and their removal can affect 'mouthfeel' - debated.

Most distillers remove these molecules through process of chill filteration. Whisky is flash chilled to induce precipitation of the fatty molecules into suspension. This allows physical removal by very fine filtration. Can range from -8 deg to +8 deg.

Blended whisky less suseptibel to flocculation due to the grain aspect but is usually chill filtered for stability or visual reasons.

SMW distillers are concerned for the loss of congeners. Leads to increased ABV eg: cask strength of 46%+. These whiskies have increased duty but can wthstand extreme temps changes as the increased strength retains more flavourful esters in solution.

After chill fil. it will undergo analysis for ABV, colour, turbidity. Then goes to the bottling line.

Bottling line

Most automate now. Whisky is added to the bottle, labels and closures (corks or metal tops) are added, bottles packaged.

Analysed for quality control - checked visually, labels, packaging and colour.

Grain Distillation - Scottish whisky class

Currently (2021) 7 grain distilleries in Scotland. Larger in scale than malt distilleries eg: 2014 Diageo had 28 malt distilleries and 1 grain. The 1 grain produced more per annum than the 28 malt combined.

Single grain whisky is one of 5 types of Scotch whisky under Scottish regs - product of one distillery.

Malt distilling is a batch process while grain is continuous. It uses other cereals for mashing (eg:wheat/maize) and not just malted barley. About 10-15% malt barley is needed to give enough enzymes to break down the starch from the other grains.

Fermentation is similar to malt distilling but is 'all grains in' - mash isn't filtered prior to entering the washback. Means there are solids in the fermenters/washback. Becase it's a continuous process it's easier to remove wash with grains in, rather than filtering. Sugars are still converted to alcohol with the action of yeast.

Two columns used to distill - Analyser and Rectifier. (click for image); Coffey/Patent Still is the traditional still design.

8 steps process:

• 1) Wash enter Rect via pipe and weaves down the column, out the bottom and into the Ana. Here the wash starts distilling; wash stays in the pipe and is warmed in the Rect.
• 2) Ana is full of trays; wash slowly flows down to the heat at the bottom.
• 3) Steam is added to bottom and wash is heated; the alcohol is 'stripped off' as vapour.
• 4) Vapour rises to top of Ana and then goes back down to bottom of Rect (Rect usually sits on top of Ana).
• 5) Spent wash collects at bottom of Ana and is drained continuously through the process.
• 6) Now vapour rises to top of Rect to reach the condenser, this turns the vapour back to liquid; it is collected as New Make Spirit.
• 7) If vapour becomes liquid too early it returns to the top of the Ana and starts again as 'feints'.
• 8) Vapours that are too volitile to be condensed go back to liquid by the condenser and leave the top of the Rect.

The end product = Grain NMS and can't be called Scotch Whisky until matured for 3 years; bulk of flavour comes from blending but casks still play a role in imparting colour, flavour and aroma; can be bottled at various ages or as a non-age statement product.

Blending - Scottish Whisky class

Take various whiskies (malt and grain) and combine to produce a consistent flavour profile; established in the mid-late 19th cent with some brands still familiar today eg: Dewar; a quality blend can use up to 30 malts.

Blended scotch = one or more malt whiskies and one or more grain (at least 3 yrs).

eg: Grants, Dewar, Walker's, Haig, Bells, Mackinlays; 9 out of 10 scotchs sold globally is a blend; J&B has 42 malt and grain whiskies.

'Packing' malts - neither dominate or mask the essential character of the blend but are themselves good whiskies eg: heartland Speyside / Highland one sought after along with some Lowlands. Islays treated with care due to their strength which stands out.

Thought that the flavour development of grain whisky during longer maturation was limited (debated) and so in a 12 year old blend (for eg) the malt component would be increased.

There is an interest in malt to grain ratios but MB tend not to divulge their recipes; a quality blend may have 40-50% malt while a lower quality may have 15-20% malt.

Quality blend tend to reflect malts between 5-9 years and grain younger at 4-5 years, unless an age statement demands a higher minimum age.

Master Blender

Traditionally the MB relies on nose and palate to achieve desired character and flavour; aims to be consistent in colour, flavour and aroma every time the blend is produced; MB takes account of age variants, cask character, regional styles and individual character.

Through nosing and tasting the Blender identifies malts that will determine the key character / 'signature' of core malts - could be up to 6 malts and often reflect the malt distilleries owned by the blender.

Some Blenders have a long-term contract to purchase malts, often in exchange for similar supplies of own quality malts; Blender will have availalbe substitute signature malts in case of supply problems, commercial interuptions ore quality problems with a malt.

Skill is repected and blending families identify early one the blenders of the next generation to inherit 'the nose', trained over time.

Other blending notes

Blending = mixing of whiskies of different ages and characteristics / Vatting = blending of malt whiskeys from more than one distillery

Blending should smooth our differences in aroma, flavour and colour between casks. Cask individuality is removed by blending to enable consistent flavour each year.

Blended Scotch usually from a range of distilleries, and 20-50 of grain and malt whiskies of varied ages. Can contain 5-70% malt whiskey. 'Standard', 'premium' and 'deluxe' denote amount of malt whiskey in the blend - higher levels in ach category. Usually have mix of light and heavy bodied whiskies.

• Light - Scotch grain whiskey, Irish grain whiskey and American light whisky and neutral grain spirit
• Heavy - Scotch malt, Irish pure pot still, many column still whiskies (have lower ethanol concentration)

Need to maintain consistency of colour and can use spirit caramel to do so.

Quality ia found in the 'noses' - experienced blenders - samples usually assessed by aroma not taste. Gas chromatography can be used to analyse characteristics such as phenolic compounds and esthers. Usually takes 10 years to train to be a nose.

After blending, whiskey may be stored (married) for up to two years in casks. This doesn't normally add any extra character.