Scotch Production Flashcards
Production
What are the 4 high level stages of producing scotch whisky?
- Mashing
- Fermenting
- Distilling
- Filling/Maturing
Maturation
What is the most common type of cask used for whisky and how much does it hold?
hogshead
Holds 55 gallons/250 liters
Malting
At what point in the germination process to maltsters want to capture the barley?
When the cell walls have been broken down, but before the starch begins to be used by the growing plant.
Malting
How do maltsters stop the growth of green malt?
By drying it in the kilning process.
Fermentation
What amount of yeast is typically used for eight tons of mash?
175kg
Fermentation
What have modern distilleries fitted in their washbacks to help control fermentation?
They fit them with mechanical switchers to break the foam up.
Fermentation
What is the fermenting vessel called?
A washback
Fermentation
Do scotch whisky distillers typically use a brewers yeast or a cultured yeast?
cultured yeast, grown from a single cell
Fermentation
What percentage of the weight of malt mashed is “pitched” with yeast?
2.2%
Distillation
Which type of condenser affords more copper-contact?
shell-and-tube condensers
Distillation
What are the two main types of condensers?
worm-tub and shell-and-tube
Distillation
What can distillers do to a worm-tub condenser to encourage more copper-contact?
They can hold back the water in the worm-tub so it becomes hot to slow the liquification process.
Distillation
Why do distilleries typically use copper in the distillation process?
Copper is a purifier
Distillation
Would a distiller cool a condenser with warm water or cold water to get a purer, lighter spirit and why?
A distiller would use warmer water to get a lighter spirit because the spirit would take longer to liquify in the condenser, resulting in more contact with the purifying copper.
Distillation
What is the flavor profile of a spirit distilled with a condenser in very cold water and why?
The resulting spirit would be heavier and more “traditional” in flavor because it liquid was condensed quickly in the cold.
Production
What season does distilling traditionally occur and why?
Distilling was traditionally done in the winter for two reasons:
- Because the cooler temperatures allow for slower liquification
- Because of climate change, water levels tend to be lower during July and August
Production
What is the “silent season” and when does it typically happen?
It’s a time when the distilleries close down their site for maintenance and holidays. It typically happens during the summer because winter is preferred for distilling.
Malting
How many times is barley immersed in water to increase moisture content and activate the enzymes?
3 times
Malting
How many times is barley steeped in water to increase moisture content and activate the enzymes?
3 times
Mashing
How long does the steeping process typically take and what 5 things can that depend on?
2-3 days
- nitrogen level
- temperature of the water
- ambient temperature
- size of the grains
- their capacity for absorption
Malting
What can a maltster do to remediate under-steeped grain? Over-steeped?
if under-steeped they can spray the grain with more water
if over-steeped they can dry it out in a tumble-drying process
Malting
What two reasons to maltsters aerate the barley when steeping?
To ensure equal uptake of water and to prevent clumping.
Malting
At what depth do malsters spread the barley on the concrete floor during germination?
~30 cm
Malting
What two things do maltsters check to ensure the grain is correctly modified?
taste and texture
They want it to taste sweet and for the texture to be chalky and smooth when biting
Malting
Floor malting has been primarly replaced by what “centralised” system.
pneumatic malting systems
Malting
What company developed the SGKVs and when did they create it?
Moray Firth Maltings in the late 1970’s. (Since merged with Bairds malt)
Malting
What are the two types of pneumatic systems operating today?
Rotary Drums & Steep, Germinate and Kilning Vessels (SGKV)
Malting
Describe how a rotary drum is used in the malting process?
It is charged with 9-50 tons of steeped grain and is rotated 9 times a day while humidity and temperature is controlled.
Malting
What are the two types of modern kilns and how do they work?
direct fired: gases of combustion pass directly through the malt
indirect fired: air is heated by oil fired-burners or steam-heated-radiators before passing through the malt
Production
Why do malt whisky distilleries often have the pagoda-style roof?
The kilns have tapering roofs to draw out heat from the furnace and they’ve been capped with pagoda roofs since the 19th c.
Malting
What are the three stages of the kilning process and what are their purposes?
- Free drying phase: evaporate moisture on the surface of the green malt
- Forced drying phase: reduce mooisture content of malt to~ 5%
- Cooling phase: prevent further curing of the malt
Malting
At what stage of the kilning process to maltsters add peat?
During the free drying phase
Malting
Does a lower temperature in the free drying phase translate to higher or lower peatiness if peat is used during kilning? Why?
A lower temperature results in higher level of peatiness. Phenols only adhere to the barley husk when they are damp, so keeping smoke high and heat low translates into this flavor.
Malting
About how many hours does the process of kilning take? What three things affect this time?
20-48 hours
- the type of kilning process
- the size of the kiln
- the amount of malt
Mashing
What are the three things distillers test when malt arrives to the distiller before it is accepted?
- moisture (<= 12%)
- viability for germination (99% viable)
- Insect infestation
Mashing
What is the purpose of the two sets of rollers in a mill?
One roller cracks the husks
Other roller grinds the malt
Mashing
What happens if ground malt is too fine? Too course?
If it’s too fine, the mash tun will not drain quickly enough.
If it’s too coarse the liquor will drain too fast and you won’t get maximum extraction.
Mashing
Fill in the blanks.
Mashing reawakens the enzyme ____ and this allows it to complete the conversion of ____ into ____.
amylase
starch (dextrin)
maltose
Mashing
What is the name of the large circular vessel where mashing takes place? What material(s) is it typically made of?
mash tun
Typically made of stainless steel or cast iron and covered with a copper top.
Mashing
What is the liquor drained through the perforated floors of the mash tun called?
worts
Mashing
What is the typical size of a mash tun and what is this size related to?
1-15 tons
Their size is related to the size of the fermenting vessels they fill.
Mashing
1 ton of malt is expected to create how many litres of worts?
5000 litres
Mashing
What german invention have most distilleries adopted to their mash tuns to increase extraction.
Lauter tuns
Mashing
How many waters or “extractions” are used in the mashing process?
3
Mashing
What are the typical temperatures and times for the three stages of mashing?
- 63-64 C @ 20 mins
- 70 C @ 30 mins
- 85 C @ 15 mins
Mashing
What do the worts in the underback pass through before heading to fermentation? What two important things does it do and why?
a heat exchanger
it recudes the temperature to below 70 C to prevent decomposing the maltose and killing the yeast
Fermentation
What is the name of the vessel where fermentation occurs?
washback
Fermentation
What 3 materials are washbacks made from? Why?
Larch, Pine (Douglas Fir), and stainless steel.
The pines grow tall and have a tight grain with few knots,
Fermentation
How is the process of fermentation in whisky production different from brewing beer?
The process with whisky is non-sterile
Fermentation
Describe the principles of fermentation
Yeast requires oxygen to multiply. When it is deprived of oxygen, it extract oxygen from the sugars in the wash, producing alcohol and carbon dioxide.
Fermentation
What does it mean that there are anaerobic conditions during fermentation?
It means there is an absence of air. This forces the yeast to extract oxygen from the sugars in the wash.
Fermentation
How high is the spirit typically filled inside the washback?
About 2/3 full
Fermentation
What form is yeast typically added and when is it typically added?
The yeast is tyipcally in the form of a solution and is added as the worts enter the back.
Fermentation
When do the worts become wash?
Once the worts are filled in the washback and the yeast is pitched in.
Fermentation
Describe the three main phases of fermentation
- “log phase”: the yeast acclimates to its surroundings (couple hours)
- yeast multiply rapidly, consume sugar and produce alcohol and carbon dioxide. Temperature increases.
- Alcohol inhibits activity of the yeast and bacteria grows. Second bacteriological fermentation occurs. (~12 hours)
Fermentation
How hot can the wash get during the second phase of fermentation?
35 C / 95 F
Fermentation
Describe the bacteriological fermentation that occurs during the final stage of fermentation.
Bacteria mainly comes from the malt in the form of lactic acid/lactobacillus. They lower the pH/acidity and allow further flavors to develop.
Fermentation
Describe the characteristic of a spirit produced from 48 hr fermentation vs 60+ hr fermentation.
2 day: malty and cereal like
60+: complex, fruity and floral
Fermentation
What is the typical lifespan of a wooden washback?
~ 40 years
Fermentation
How much alcohol are distillers expected to extract per tone of malt.
420 litres / 92 gallons
Fermentation
Secondary fermentation may increase ____ and ____, but can reduce ____.
flavor
complexity
extraction
Fermentation
What are some claims that distillers make about the benefit of wooden washbacks?
- Beneficial reaction between alcohol and bacteria in the wood
- Well seasoned wood adds esteriness to flavor
- Better insulation in winter months
Distillation
Distillation separates the ____ from the ____ in the ____ and ____ it.
alcohol
water
wash
concentrates
Distillation
What is the name of the vessel where distillation takes place?
pot still
Distillation
What is the name of the narrow neck that connects the pot still to the condenser?
“lyne arm” or “lyne pipe”
Distillation
How many distilleries still use worm-tubs?
15
Distillation
How many stills does malt whisky require? Are there ever more?
2
Occasionally a third is installed
Distillation
What are the names of the two stills required in distillation?
- wash or “singling still”
- low wines or “doubling still”
Distillation
Which of the two stills is tyipcally larger and why?
The wash still because it’s required to hold greater amount of liquid.
Distillation
What are the three basic designs of stills? Which is most common?
- plain/onion
- boil-ball
- lantern
The most common is the plain or onion shape
Distillation
What vapors do very tall stills allow for?
Allows lighter, volatile vapors to be collected and heavier more oily vabors to fall back as reflux.
Distillation
Which is more important, the shape of the stills or how they are operated?
How they are operated
Distillation
Copper is a purifier that removes what two undesirable compounds? Which distillation does this occur?
sulphury and vegetal compounds
during first distillation
Distillation
Does a smaller still result in more or less copper contact?
A smaller still results in greater surface area of copper per unit of vapour
Distillation
How does a narrow neck affect the speed of the ascending vapors and the resulting copper contact?
A narrow neck accelerates the velocity of the vapor and reduces copper contact
Distillation
What did distillers change in the distillation process during the 60s & 70s to allow for better heat control?
All but a handful of distilleries switched from direct firing (flame) to indirect firing (steam-heat or coils in the body of the still)
Distillation
What are direct fired stills fitted with to prevent solid particles from scorching in the still? What are they made of?
rummagers
copper chain mail
Distillation
The wash pumps from the ____ to the ____ and thence to the ____.
washback
wash charger
wash stil
Distillation
The wash still is charged at what capacity in order to allow for expansion as the wash is heated.
Between 1/2 - 2/3
Distillation
What is the ABV and temperature of the wash as it enters the wash still?
~8% ABV
26 - 32 C / 79 - 92 F
Distillation
What is the name of the window on a still that distillers use to check the behavior of the wash?
sight glasses
Distillation
Why does a distiller not want too much foaming? How do they prevent that?
Because the foam might carry over the neck of the still and into the distillate. They reduce the heat once they see the foam in the sight glass.
Distillation
Will a wash with a longer fermentation be more or less frisky/volatile than wash with a shorter fermentation?
A longer fermented wash will be less frisky and might settle in 15 mins
Distillation
What does it mean when the wash is said to “come in”?
When it has settled during it’s first heating
Distillation
What does it mean to “break the head” and how does the distiller do it?
When the distiller mixes up the foam by gradually increasing the heat a few times.
Distillation
What oily, yeasty compound can collect in the neck and worm if there is too much action? What taste can it impart? Is this tyipcally removed?
furfurol
burnt and acrid taste
No, because some amount is said to be good for flavor
Distillation
The wash still is run until the remaining liquid is at what ABV%?
~1%
Distillation
What are three names for the residue from the first distillation? What percentage of it is solid?
pot ale
burnt ale
spent wash
~4% solid
Distillation
The high protein spent wash is converted to a syrup and combined with ____ to turn into ____ for livestock fodder.
draff
dark grains
Distillation
The low wines are about what ABV% before and after they pass through the low wines and feints charger? What is used to fractionate this in the charger?
21% before
at least 28% after
The foreshots and feints (heads/tails) from previous low wine distillation.
Distillation
The second distalltion further ____ and ____ the spirit.
purifies
concentrates
Distillation
What are congeners? Do distillers want them eliminated?
Organic chemicals like esters, aldehydes, furfurol amd other compounds of hydrogen, oxygen and carbon that are impurities.
No they impart flavors to the whisky. Distillers want the right amount.
Distillation
What are the three runnings or fractions of the second distillation called?
- The foreshots or “foreshows”
- The cut
- The after-shots or “feints”
Distillation
At what temperature and ABV do the foreshots come over?
84 C / 183 F
~75-80% ABV
Distillation
What is the brass-bound glass fronted box that the runnings flow through?
The spirit safe
Distillation
What two ways does the distiller test for purity?
- The demisting test where they add water to see if the spirit goes cloudy
- Checks the hydrometer for strength
Distillation
While the point at which distillers make the cut varies, what is the ABV strength and how long does it typically take to get there?
72 - 75% ABV
~ 15 - 30 mins
Distillation
What are the 2 most important esters from an aromatic/chemical point of view?
isoamyl acetate
ethyl caprylate
Distillation
Describe the three key aromatic groups in malt whisky?
esters: fragrant, fruity, pear, bananas, roses
feints: biscuity, porridge, leather, honey
phenols: peat
Distillation
The acceptable cereal feints are organo ____ compounds while the unacceptable feints are organo ____ compounds
organo-nitrogen
organo-sulphur
Distillation
If a distiler wants a more robust whisky, do they run the cut shorter. or longer and why?
They would run it longer to include more of the feints.
Distillation
If distillers look for a lighter whisky character, do they cut at a lower or higher ABV? What percentage might that be?
higher
as high as 69%
Distillation
At what point to the esters, feints and phenols appear in the second distillation?
esters at the beginning
feints half way through
phenols about a third of the way
Distillation
Where does the spirit from the latter part of the second distillation go?
To the low wines and feints receiver
Distillation
What is the name of the liquid run down to 1% at the end of the second distillation and where does it go?
The “spent lees”
they are waste
Distillation
What fraction of the charge to the still is produced as feints or spirits in the second distillation?
1/12 - 1/13
Distillation
The saved spirit from the low wines still goes into what vessel before filling? What. isthe ABV at this stage?
The intermediate spirits receiver
~70%
Distillation
What is the spirit called prior to it being aged?
“new-make spirit”
or
clearic
Maturing
What ABV is the optimum strength for maturing
63.5%
Maturing
Will filling at a higher strength increase or reduce the number of casks required? What’s the tradeoff?
reduce the number of casks, but will take longer to mature
Maturing
Contemporary sensory scientists estimate that maturation can account for what percentage of the flavor in whisky?
80%
Maturing
What year was it made a legal requirement to use casks made of oak?
1990
Maturing
How old do trees have to be to be used for casks?
At least 80 years old
Maturing
What are the two types of oak used and the flavors they can impart?
American oak: sharp, turpentine, pine
European oak: resinous, fragrant, astringent
Maturing
Describe the chemistry of oakwood and how it affects the spirit
cellulose: little contribution
hemicellulose: carmelises adding sweetness and color
lignin: blending agent, pulls together, vanilla,
tannins: astringency, delicacy
wood extractives: bourbon sherry
Maturing
Oakwood facilitates oxidation which has what effect on the spirit?
removes harshness
increases fruitiness
adds complexity
Maturing
What is a “straight whiskey”?
A spirit filled and aged in new casks
Maturing
Nowadays the term “sherrywood” refers to what kind of oak?
European oak
Maturing
Ex-bourbon casks account for what percentage of casks coming into the system?
~90%
What are the two categories of ex-bourbon casks?
after-bourbon barrels: aka american standard barrels 180-200 litres
re-made hogshead: aka dump hogshead 250 litres
Maturing
5 ASB’s can be reassembled to create how many hogshead casks?
3
Maturing
What are the names of two types of 500 litre capacity casks that used to hold sherry?
butts and punchen
Maturing
What type of sherry is typically used to season? What other type is sometimes used?
oloroso
fino
Maturing
How long are casks seasoned with sherry before use?
1-4 years
Maturing
What is an “ex-solera” cask?
A cask that was used to mature sherry
Maturing
What wine is typically used for ex-wine casks?
Port
Maturing
Will smaller casks mature at a slower or faster rate? Why?
Smaller casks will mature faster because there is a higher surface to volume ratio
Maturing
Which wood can be used beneficially more times?
sherrywood
Maturing
What is the average stock of casks in Scotland?
20 million
Maturing
The cask performs what three vital mechanisms in maturation?
- additive: add flavors
- subtractive: remove unwanted flavors
- interactive: allow spirit to interact with environment and oxidize
Maturing
What is “toasting” and what does it do?
Oak staves are heated to be bent into shape and alter the chemical structure of the casks’ inside surface.
Maturing
Toasting degrades what two chemicals that produce caramel, vanilla, and coconut flavors that leech into spirit?
hemi-cellulose
lignin
Maturing
What is “charring”, what benefit does it provide and when does it occur?
When. theinsides of the barrel are set on fire. The carbon char acts as a purifier to remove sulphuric compounds. It happens after toasting?
Maturing
What types of casks are not charred?
Sherry casks
Maturing
Even if a cask previously housed bourbon or sherry, the first time a cask is filled with scotch spirit it is referred to as what?
a first fill
Maturing
After a scotch cask has been used for a first-fill, it is referred to as what?
A refill cask
Maturing
Why is a refill cask desirable for longer maturation?
A first fill cask is more active and can dominate the flavor of the spirit.
Maturing
Are most of the casks used by the scotch industry first-fill or re-fill casks?
re-fills
Maturing
How many fills is a cask tyipcally good for before it is considered “exhauseed” or “spent”?
3-4 fills
Maturing
How can casks be rejuvenated?
They can be reamed out, re-toated, and burnt to reactive the layer below.
Maturing
What is the process of re-toasting a casks called?
“de-char, re-char”
Maturing
What are the two types of warehouse?
bonded or “dunnage” warehouses
modern “racked” warehouse
Maturing
What percentage of volume is lost per year as the angel’s share?
~2%
Maturing
Which type of warehouse sees more humidity and air circulation? How does that affect the volume, strength and taste?
Dunnage
high volume, lower strength, more mellowness
Maturing
Does scotland see more temperature fluctuations on the coast or inland?
inland
Maturing
How does whisky differ from wine in the bottle?
Whisky does not continue to mature in the bottle
Maturing
Whisky cannot be called Scotch until it has matured for ahow many years?
3
Maturing
Generally, which whiskies mature more quickly? Lighter or heavier malts?
lighter
Maturing
Does whisky steadily mature or does it occur in fits and starts?
fits and starts
