Spirits production Flashcards
What are 5 steps in spirits production?
- selecting raw material.
- processing the raw material.
- alcoholic fermentation.
- distillation.
- post-distillation procedures.
What do raw materials give?
Flavours.
Carbohydrate (in form of either starch, sugar or inulin).
Fermentation requires what?
Sugar solution plus yeast.
Fermentation produces what?
alcohols
congeners
carbon dioxide
heat
How can one increase the number of congeners?
By leaving fermented liquid to stand after fermentation, allowing more to develop.
How is control of congener development exercised?
No (or very rarely) wild yeasts.
Consistent temperature in fermentations.
Consisten amount of sugar in solutions to be fermented.
What are the names of the fusel oils?
propanol
butanol
amyl alcohol
What are the three main sources of congeners?
esters;
acids;
aldehydes;
sulphur compounds.
Define ‘rectification’.
The progressive increase in the level of ethanol as a result of reflux.
What is the range of numbers of rectification plates found?
From 3 to 42. Column stills have between 15 and 42.
Where are pot stills used?
Cognac and Scotland.
What are the three options for heating a pot still?
- direct flame (compulsory in Cognac);
- steam - either circulated in internal pipe or external jacket;
- water bath - a bain marie.
Explain temperature gradient and its effects.
The hotter the heat the less the gradient. With low gradient the less volatile congeners make it into the final spirit. A gentler heat means more reflux and a more highly rectified spirit.
How is reflux created in pot stills?
The greater the height of the head of a pot still the greater the reflux.
Angle of linking tube important: the steeper the angle the higher the more reflux.
Can a pot still have rectifying plates?
Yes, up to 3 or 4 are often added to modern pot stills.
What is typical abv of the product of first distillation in a pot still?
23% for whisky, 25% for grappa.
Which distillation in a pot still is divided into heads, hearts and tails?
The second distillation.
What is found in the heads? And what is found in the tails?
Heads: methanol.
Tails: fusel oils.
In peat flavoured whisky does the cut to tails come early or late?
Late. The congeners which give peat flavours and aromas have a high boiling point.
In a two column still what are the names of the first and second columns?
First: the analyser, or stripper.
Second: the rectifier.
Why is rectification beyond 96% abv desirable?
- part of style of vodka and light rum.
- to make a base spirit for gin.
- a legal requirement in EU to have low methanol levels.
What removes fusel oils?
Hydroselection.
What does de-methylising do
It reduces methanol levels.
Explain hydroselection.
Fusel oils are more volatile when liquid is 20% abv. Therefore you dilute with hot water and heat and the fusel oils go out of the top of the hydroselection column. Then put through a rectification column to take it back to 96%.
In a 5-column still what are the names of the columns?
- Analyser or stripper.
- Rectifier.
- Hydroselection column.
- Rectification column.
- De-methylising column.
Which evaporates the most where?
Alcohol evaporates in Scotland.
Water evaporates in WI and USA.
Name the three species and origin of oak most often used for barrels.
Quercus alba - USA
Quercus robur - Europe
Quercus sessiliflora - Europe
How does the barrel alter spirit?
Flavours from the wood; flavours from previous contents; flavours from charring; charring can act as filter and remove negative flavours.
Why are spirits generally diluted before being put in barrel?
Because too high ethanol level can extract unpleasant flavours from wood.
What is the official name of spirit caramel?
E150a
What is E150a?
Spirit caramel.
What are the three typical finishing processes for spirits?
Dilution;
Colouring;
Filtration.
