Distilling Knowledge Unit 1 Flashcards
What are the 5 main steps that are common to all spirits?
Selecting raw materials processing raw materials alcoholic fermentation distillation post-distillation operations
What 2 things to raw materials give distillers?
Unique set of flavor that give spirits recognizable flavor signature
Store carbohydrates that distillers use in order to make a sugar solution for the yeast to feed on during fermetnattion
What 3 forms do plants store carbohydrates?
Sugars, starch, inulin (sugar which yeast can feed on is found in grapes and sugar cane)
What starches can not be consumed by yeast?
Starch found in grains and potatoes and inulin found in agave are insoluble in water and cannot be consumed by yeast. Consequently starch and inulin must be converted into sugars.
What two important outcomes come about from alcoholic fermentation
It produces alcohols and flavor compounds (congeners)
How is small-scale fermentation carried out?
Small producers ferment in batches. One fermentation is completed before another begins
How is large-scale fermentation carried out?
Often uses a process of continuous fermentation, which is able to produce greater volume of alcoholic liquid more consistently and efficiently
Why is wild fermentation rare
Most distillers buy yeast from suppliers because each yeast strain produces a different range and number of congeners
Why is it important that all the conditions that can alter the behavior of the yeast are kept consistent
Yeast behave differently as their environment changes, they can produce different variations in flavor.
What is the most abundant alcohol?
Ethanol
What are fusel oils?
A group of alcohols that include propanol, butanol and amyl alcohol
What are the 3 main sources of congeners?
1) raw material
2) product of yeast
3) chemical reactions between congeners and or alcohols
What are some important groups of congeners?
Esters - Fruity aroma
Acids
Aldehydes
Sulfur Compounds
What are fractions?
Through the use of boiling and condensing an alcoholic liquid into its different parts. Most important are ETHANOL and WATER
What temperature does ethanol boil at?
78.3C
As the ethanol in a spirit becomes more concentrated the number of congeners falls therefore…
spirits that are distilled to a high strength are lighter in character as they have fewer congeners than those that are distilled to a lower strength
What are 3 reasons to use copper for a still?
Easy to shape
Excellent conductor of heat
Reacts with sulfur compounds and removes them from the final spirit
What is reflux?
Whenever liquid and vapor mix in a a still the heat they have is shared between them, resulting in the more volatile fractions of both becoming vapor and the less volatile fractions becoming liquid.
What is rectification?
The progressive increase in the level of ethanol as a result of reflux. More reflux mean more rectification and more alcohol
How many rectification plates can there be in a still?
3-42 plates
What style still does not use a condenser
Continuous
What two parts make up a condenser
Tube where vapor enters and liquid exists
Coolant (usually water)
What are the two principal types of condensers
Worm Tube (oldest style, single tube) Shell and Tube (passes through a number of vertical tubes)
How do you define a column still?
Structure internally divided with rectification plates ranging from as few as 15 to as many as 42
What is batch distillation?
A liquid must undergo two or more separate distillations in order to produce a final spirit
What 5 common elements are shared in pot stills?
Heat source Pot Head Linking Tube Condenser
What are 3 methods for heating a pot still?
Direct Heating - FIRE (can damage liquid by solids getting stuck and scorching)
Steam - Circulated through a coil inside or jacket outside
Water Bath - referred to as a bain marie or bagno maria
What happens with a gentle boil?
Increses the temperature gradient and therefore facilitates more reflux limiting the passage of less volatile congeners
What happens with a vigorous boil?
More head is added to lower the temperature gradient, reducing the amount of reflux that takes place therefore increasing the amount of less volatile congeners that will make it into the final spirit
When making multiple distillations as in the case of Scotch what is the purpose of the first distillation?
To separate the volatile fractions from the alcoholic liquid.
What are the heads?
the first liquid to flow off the still, contains high concentrations of volatile fractions particularly methanol which while toxic also tastes gross
What is the heart?
The portion that is used to make the final spirit, high concentration of ethanol
What are the tails?
As the boiling point of the liquid changes more fusel oils distill over which can add weight but at some point make a spirit unpalatable. It is up to the distiller to decide when to cut the tails and separately collect the remaining liquid.
What type of still is used for batch distillation?
Mostly Pot but also Column still
What heat source is used for column stills?
either direct injection of steam or a steam-powered heat exchanger known as a ‘reboiler’
What 3 ways are used to promote reflux in a column still?
Head condenser
Liquid preheated as it is passed in a tube between the rectifications plates
Pour some of the spirit they have taken back into the still to promote downflow
What are the two stages of continuous distillation?
Analyser/stripper: Volatile fractions are separated from most of the water and the non-volatile part of the alcoholic liquid
Rectifier: the volatile fractions are rectified
How does the 1830 Coffey Still work?
Alcoholic liquid is preheated in a tube that passes through the rectifier. This promotes reflux. The hot liquid then enters the top of the analyzer and passes down through the still meeting the vapors and steam that are rising in the opposite direction
What are the two main methods for reducing the flavor of a spirit
Hydroselection - highly rectified spirit enters middle of the column, is diluted with water from above and heated from steam below, fusel oils become volatile and rise while the diluted spirit is collected at the bottom
De-methylising - spirit is gently heated in a reboiler and methanol is able to separate out over many plates (normally a necessity for vodka production in the EU since the legally required minimum level for methanol in vodka is extremely low
When is methanol most volatile?
When ethanol is at a concentration of 96%
What are the four major post-distillation operations?
Maturation
Addition of flavor
Blending
Finishing
What are 3 ways in which an oak barrel can affect the flavor of a spirit?
1) It can subtract flavor - when congeners are absorbed by the carbon on the inside of a barrel
2) Adds flavor through hundreds of congeners from the oak itself (vinillian = vanilla, lactone = coconut, eugenol = cloves and spices
3) Congeners from the oak and spirit itself react with each other and or oxygen to create even more flavor
What are the main species of oak in America
Quercus Alba
What are the main species of oak in Europe?
Quercus Robur and Quercus Sessiliflora
What are the effects of toasting and charring an oak barrel?
Purges resinous flavor and creates new flavors on the surface and a layer of carbon to remove undesirable flavor from a spirit. Charred barrels can contribute more flavor as the flavor goes deeper into the wood and creates more caron
Why does fill strength matter
Because most spirits come off a still at an abv so high that ethanol would pull unpleasant flavours from the oak
What 3 important factors of temperature and humidity effects a maturing spirit?
Rate of evaporation
Can cause the liquid to expand and push more volume deeper into the wood
Position in the warehouse can matter as temperature and humidity are different at every spot
What is chill-filtration
Some components common to all spirits can form a haze when the spirit is chilled this is removed through filtration
What does finishing involve?
Dilution Coloring and Filtration
