Distillation Flashcards
(150 cards)
1
Q
What is distillation?
A
The process by which two or more liquids are separated into smaller parts through the use of heat.
2
Q
Where does the term distill come from?
A
The Latin word destillare, which means “trickle down”.
3
Q
What does alembic mean?
A
It is the Arabic word for a still.
4
Q
What are congeners?
A
Acids, aldehydes, esters and other compounds that add distinct aromas and flavors.
5
Q
What is the boiling point of pure ethyl alcohol?
A
173℉
6
Q
What are miscible liquids?
A
Liquids that dissolve in one another.
7
Q
What is the maximum potential alcohol by volume for commercial distillation?
A
96.5%
8
Q
What are heads?
A
The first part of the distillate to come off the still. Also known as foreshots.
9
Q
What are foreshots?
A
Another term for heads, the first part of the distillate to come off the still.
10
Q
What are low boilers?
A
Volatile compounds with low boiling points. Often non-potable or even dangerous.
11
Q
What are high boilers?
A
Compounds with high boiling points. They may be unpleasant, non-potable or toxic.
12
Q
What are tails?
A
The last part of the distillate. Also called feints.
13
Q
What are feints?
A
Another term for tails, the last part of the distillate.
14
Q
What is the heart?
A
The center part of the distillate, the potable spirit.
15
Q
What are the points of separation between the heads and heart and the heart and tails called?
A
Cut Points.
16
Q
What is reflux?
A
The interaction of gas and liquid during distillation.
17
Q
What is rectification?
A
The process of concentrating the alcohol content in a liquid by repeated distillation. The cumulative effect of reflux.
18
Q
What is fractional distillation?
A
The separation and concentration of the mixture of two or more liquids with different boiling points through repeated evaporation and concentration procedures.
19
Q
What is a worm condenser?
A
A spiral metal tube connected to the still that assists in rapid condensation of the vapors.
20
Q
What is a lyne arm?
A
The part of the pot still that transfers the vapors from the still to the condenser.
21
Q
What is a Coffey Still?
A
A column still, sometimes called a Patent Still.
22
Q
What part of the distillate contains high boilers?
A
The tails.
23
Q
What portion of the distillate contains low boilers?
A
The heads.
24
Q
What is pyrolysis?
A
A series of chemical changes brought about due to elevated temperatures.
25
What type of still works in the batch process?
The Pot still
26
What is the term for the first batch of distillate off a pot still in brandy production?
Brouillis
27
What is the term used for the first batch of distillate off a pot still in whiskey production?
Low wines
28
What is a Hydroselector Column?
Also called a purifier column, the part of a multiple column still where hot water is added to the distillate to help remove congeners.
29
What is a rectifier?
A column (or columns) of a multiple column still where the final distillation takes place.
30
What is a new make spirit?
The term used for all newly distilled spirits.
31
What is a downcomer pipe?
A pipe connecting plates in a column still with a damn level where overflow goes down to next plate.
32
What is the typical alcoholic concentration after the fourth (or fifth) batch using a pot still?
55-70%
33
What is the typical percentage of alcohol in the first batch off of a pot still?
About 25%
34
What is a batch process?
The process used for a pot still, a batch of fermented beer/wine is loaded into the still. The pot is then cleaned, and the batch is put into the still again. May be repeated 3 or more times.
35
What is a multiple column still?
Additional columns are added for a purer product - possibly hydroselector and/or rectifiers.
36
What is a small batch?
An unregulated term, in some cases 10-60 specifically selected barrels but could mean anything.
37
What are the parts of a column still?
The analyzer
Stripping Section
Rectifying Section
Reboiler
Condenser
Liquid Return
38
What effect does the angle of the lyne are have on the distillate?
An arm that angles up produces a lighter/more refined distillate (more reflux)
An arm that slopes down produces a heavier, more congener laden distillate.
39
What are some terms for the leftovers that remain in a still after distillation?
Dunder
Stillage
Backset
40
What are the four stages of spirits production?
Processing the raw material
Alcoholic fermentation
Distillation
Post-distillation operations
41
Describe nearly all newly made spirits.
Clear, colorless and dry
Typically have ABV of 70% or higher.
42
What are Fractions?
Individual components making up a liquid that is to be distilled.
43
What congeners can only be added post-distillation?
Sweetness and Bitterness
44
What is a Highly Rectified Spirit?
A spirit that is at least 90% ABV (180 proof). Not a legally defined term.
45
What is a Neutral Spirit in the USA?
A spirit that is 95% ABV or more with neutral aroma intensity. Legally defined.
46
What is a Neutral Spirit in the EU?
A spirit that is 96%ABV or more with neutral aroma intensity. Legally defined.
47
Does it take more energy to make ethanol or water a gas?
Water.
48
What does volatile mean?
A substance that vaporizes at a relatively low temperature.
49
Is water or ethanol more volatile?
Ethanol.
50
What is the effect of a bigger temperature difference between the top and bottom of the still?
A greater amount of reflux.
51
How many groups are fractions grouped into by WSET?
4 groups.
52
What are Group 1 Fractions?
Fractions with the lowest boiling points. They are most concentrated in the heads.
53
What are some characteristics of highly concentrated Group 1 Fractions?
Pronounce solvent aromas
Unattractive aromas
Can give a gritty texture to the palate of a spirit.
54
What are Group 2 Fractions?
Fractions with higher boiling points than Group 1. The most important fraction in this group is Ethanol. Also includes many esters and other fractions that give a spirit its distinctive character. Most concentrated in the Heart.
55
What are Group 3 fractions?
Fractions with a much higher boiling point than ethanol. Most concentrated in the tails.
56
What are some Group 3 fractions?
Fusel Alcohols - eg Propanol, butanol, and iso-amyl alcohol
Other molecules.
57
What are some characteristics of concentrated Group 3 fractions?
Pronounced, unattractive cheesy, plastic aromas.
Can give spirit a coarse, rough texture.
58
What are Group 4 fractions?
Fractions with a very high boiling point, they never leave the still. Described as non-volatile.
59
What is an example of a Group 4 fraction?
Fatty acids.
60
What do fatty acids do the the liquid left in the still after distillation?
Make it acidic.
61
What is the effect of more reflux on the esterification of a spirit?
More of the vapor stays in the still for longer, allowing more interactions between fractions and the formation of new aroma compounds such as esters. Can enhance the fruity and floral aromas in a spirit.
62
What is effect of the exclusion of Group 3 fractions due to greater reflux?
Purer aromas and smoother texture.
63
What is effect of the exclusion of Group 3 fractions due to less reflux?
Can produce spirits with a wider range of aromas and a sharper or coarser texture.
64
What are two ways of managing reflux in a still?
Controlling the interaction between the gases and liquids.
Controlling the temperature in the still.
65
What are 3 ways of controlling the temperature in a still?
Still height and design.
Controlling the heat input
Using dephlegmators.
66
What is a Dephlegmator?
A small condenser at the top of the still, the temperature of which can be controlled by the distiller.
67
What is a head condenser?
Another name for a Dephlegmator.
68
What effect does the height of the still have on the amount of reflux?
More reflux takes place in a tall still compared to a short still.
69
What is the coolest part of a still?
The head, since it is farthest away from the heat source.
70
What is a Maillard reaction?
A reaction that takes place when a sugar reacts with an amino acid. Leads to further reactions that can add flavors to food and drinks.
71
What happens to Maillard reactions as temperatures increase?
The reactions speed up.
72
How do Maillard reactions contribute to the production of Cognac?
When the lees are distilled with the wine, the level of amino acids in the still increases, increasing the potential for Maillard reactions.
73
What are some ways to increase Maillard reactions in distillation?
Use of lees
Using direct heat (creates hot spots).
74
How are esters created?
A fatty acid reacts with an alcohol. Increasing heat increases ester formation.
75
What are two ways distillers can increase esters in the still?
Direct heat
Increasing Reflux.
76
What is the effect of atmospheric pressure on the boiling point of a liquid?
As pressure decreases, the boiling point goes down.
77
Do all fractions' boiling points decrease at the same rate when atmospheric pressure is lowered?
No.
78
What are two reasons some distillers in Japan use low-pressure stills?
To separate out fusel oils with greater degree of precision.
To reduce the amount of Maillard reactions.
79
What is a benefit of low-pressure stills related to aromas?
Low pressure stills allow distillers to collect very delicate aroma compounds that may be destroyed by higher temperatures in standard stills.
80
What are some requirements for using low-pressure stills?
Must have reinforced structure to withstand the pressure differences inside and outside of the still.
Special equipment needed to run condensers at much lower temperatures and pressures.
81
Is it more or less expensive to run a vacuum still, and why?
It is more expensive to run due to the amount of energy required to create and maintain a vacuum.
82
How do distillers remove sulfur compounds from spirits?
Through the use of copper or clay stills. The copper reacts with the sulfur, creating new copper compounds with no aromas. Clay removes the sulfurs due to its irregular surface.
83
Why is sulfur present in liquids prior to distillation?
Yeast produce small amounts during fermentation.
84
What are the four fundamental parts of a pot still?
A heat source
A pot for liquid to be distilled
Pipes that carry vapors from the pot
A condenser
85
What are the three main types of heat sources?
Direct heat
Indirect steam heat
Direct steam heat.
86
Where is direct heat a legal requirement for distillation?
Cognac
87
Where is direct heat from wood or coal often used for distillation due to the lack of infrastructure for small individual distilleries?
Mezcal production.
88
What type of direct heat is often used by larger scale distilleries?
Gas burners.
89
What is often used in distillation where direct heat is utilized?
Mechanical scrapers or stirrers.
90
What is a potential problem (or benefit) of using direct heat for distillation?
Scorching, which can give unpleasant flavors. However if well controlled can result in Increased Maillard reactions and further esterification that can add to the flavor of the final spirit.
91
What are the main methods of using indirect steam heat for distillation?
Coils
Jackets
Reboilers
92
Why are coils not frequently used to provide indirect heat for distillation?
They can still cause scorching.
93
What is a variation sometimes used with jackets in distillation?
The steam may be replaced with boiling water.
94
What is a Reboiler?
An external heat exchanger sometimes used to provide the heat for distillation. The liquid is pumped to the reboiler and then recicrulated back into the still.
95
When is direct steam used for distillation?
When working with a fermented product with a high amount of solids.
96
What are some types of spirits where direct steam may be used for distillation?
Solid state fermentations (only option for heating)
Pomace brandies (may use indirect heat, by steam injection preferred).
97
What is another term for direct steam heat in distillation?
Steam injection
98
What are some design features of pot stills that a distiller considers when selecting a still?
Still height
Designs to promote reflux (rectification plates and purifiers, dephlegmators - rare in pot stills)
Condenser - (worm tub, shell and tube or bowl of water)
99
What effect does the angle of the pipe linking the pot to the condenser have on reflux?
If the pipe angles down, reflux is less. If angled upwards, condensation flows back into the pot resulting in continued reflux.
100
What is the most widely used condenser today?
The shell and tube condenser.
101
What are two advantages of shell and tube condensers?
More energy efficient and take up less space than worm tub condensers.
Larger surface area collectively than single pipe in worm condenser tub.
102
What is the benefit of a larger cooling pipe surface area for shell and tube condensers if they are made of copper?
They can remove more sulfur compounds, resulting an a lighter and cleaner style of spirit.
103
Where are bowl of water condensers most often used?
Mexico (common)
Korea, China, Japan (sometimes)
104
Why are bowl of water condensers rarely used today?
They can only be used with small stills.
105
What is the aim of the first distillation in Scottish double pot still distillation?
To concentrate the ethanol and volatile fractions by removing some water as well as Group 4 fractions.
106
What are the outputs the first distillation in Scottish double pot still distillation?
Low wines
Liquid waste
107
What is the typical ABV of low wine in Scottish double pot still distillation?
About 25%.
108
What is the typical ABV of the first liquid to flow from the condenser in Scottish double pot still distillation?
About 55-60%
109
What is the aim of the second distillation in Scottish double pot still distillation?
To create a spirit by concentrating and selecting Group 2 fractions.
110
What are the outputs of the second distillation in Scottish double pot still distillation?
Heads and Tails
The Heart
Liquid Waste.
111
What happens to the temperature of the liquid in the still as the concentration of ethanol and other volatile fractions decreases?
The boiling liquid slowly increases towards 212 degrees, the boiling point of water.
112
What is a potential benefit of some Group 1 fractions in a spirit?
An attractive aromatic lift.
113
What are some potential benefits of some Group 3 fractions in a spirit?
Palate richness
Extra complexity.
114
What are 4 factors that can influence the amount of Group 1 and Group 3 fractions that will be present in a spirit?
The design of the still
The personal preference of the distiller
The customer
Whether it is going to be matured in oak.
115
Why do distiller typically recycle the heads and tails in their next second distillation?
To try to reclaim some of the Group 2 fractions that were excluded during the cuts.
116
What is a result of a narrow cut in distillation?
Fewer Group 1 and 3 fractions are included, resulting in a purer, smoother spirit.
117
What is the result of a wide cut in distillation?
A greater proportion of Group 1 and 3 fractions are included in the spirit, resulting in a spirit with more complexity as well as a textural sharpness.
118
How does a small temperature difference between the temperature at the top of the still and the boiling liquid affect the difficulty of separating the fractions?
A smaller temperature difference makes it harder to separate Group 1 and 3 fractions.
119
How does a large temperature difference between the temperature at the top of the still and the boiling liquid affect the difficulty of separating the fractions?
A large temperature difference makes it easier to separate Group 1 and 3 fractions.
120
What are three challenges of distillation using pot stills?
Higher operating costs
Inability to make highly rectified spirits.
Build-up of Group 3 fractions during extended periods of distillation.
121
How are most column stills heated?
Indirect steam heat (reboilers or steam jackets) or steam injection.
122
Where is direct heat required for column stills?
Armagnac.
123
What is a disadvantage of direct steam heating?
It adds water that must be removed later.
124
What are the two options for the internal structure of column stills to control the amount of reflux?
Rectification plates (most common)
Packed columns.
125
What are two design features of column stills that overcome limitations of pot stills?
Can make highly rectified or neutral spirits.
Can be run continuously.
126
What are the two most common types of rectification plates?
Bubble cap
Sieve plates.
127
What are packed columns?
Column stills filed with little bits of material such as metal or glass
128
Where are packed columns widely used?
China, baijiu stills.
129
Do all column stills need condensers?
No, in some designs the newly made spirit flows out as a liquid.
130
What type of condensers are typically used with column stills?
Shell and tube condensers.
131
Where is a variation of the worm tub condenser used with a column still?
Armagnac.
132
What are the two halves of a single-column still?
Stripping section
Rectifying section
133
Which is the hotter part of the still, the stripping or rectifying section?
Stripping section.
134
Which is the cooler part of the still, the stripping or rectifying section?
Rectifying section.
135
What happens in the stripping section of a single-column still?
Groups 1, 2, and 3 fractions rise up in the vapor and move in the rectifying section. The liquid waste and water flow out the bottom.
136
What part of the single column still performs a similar role to a first pot still distillation?
The stripping section. It "strips out" non-volatile fractions.
137
What part of the single column still performs a similar role to a second pot still distillation?
The rectifying section.
138
What three things do distillers need to keep constant in order to maintain dynamic equilibrium?
Flow rates
Temperature
Composition of fermented liquid.
139
What are the two columns in double-column stills?
Stripping column (analyzer)
Rectifying column (rectifier)
140
What are the two most commonly used techniques for further reducing Group 1 and 3 fractions in a multiple column still?
Hydroselection
De-methylising.
141
What does Hydroselection reduce in distillation?
Fusel oils (group 3 fractions)
142
What does De-methylising reduce in dsitillation?
Methanol (a Group 1 fraction)
143
Why does hydroselection make it easier to remove fusel oils in distillation?
If a highly rectified spirit is reduced to 20% abv, the fusel oils become more volatile and easier to extract.
144
What must be done after fusel oils are extracted using hydroselection?
The spirit will need to be rectified again, since the addition of water decreased the abv.
145
How is a spirit de-emthylised?
The spirit is heated using a reboiler. The methanol is concentrated up the height of the column and collected from the top of the column.
146
Where is de-methylising commonly used for vodka?
In the EU, since maximum levels of methanol in vodka are extremely low. Some materials, such as potatoes and some fruit, produce more menthol during fermentation.
147
Do hybrid stills run continuously?
No
148
What are the main parts of a hybrid still?
A pot, a column and a condenser.
149
What is a vapor infusion box?
A feature of hybrid stills where vapors pass through while operating as a pot still.
150
What are the benefits of hybrid stills?
Flexibility (can make nearly every type of spirit)
Control
