Week 1: Tasting, alcoholic fermentation and the principles of distillation Flashcards
What are the two key nutrients required by yeast?
Sugars and nitrogen.
What are the three direct outputs of the yeast’s metabolism of sugar?
Ethanol, carbon dioxide and heat.
List five key yeast outputs not derived from the metabolism of sugar?
Methanol, fusel alcohols, esters, fatty acids, sulfur compounds.
What are the two approaches to creating a sugary liquid and carrying out fermentation that distillers can take?
Sequential and parallel fermentation.
What are fatty acids?
Acids made by yeast in the fermentation process.
What are esters?
Compounds formed when fatty acids react with alcohols. They commonly have fruity aromas
What are cultured yeast?
Yeast strains that have been identified, isolated and multiplied
What are ambient/wild yeast?
Yeast in the air and on the surfaces of a distillery.
What is the name of the process undertaken by lactic acid bacteria during which malic acid is converted into lactic acid?
Malolactic conversion.
What are the 3 types of sugar?
Fructose Glucose Sucrose
What is sucrose made of?
Fructose + glucose
What are the 2 plant’s purposes for making sugar?
Using it as energy Building structure (with other nutrients)
Most common fruits to be grown for spirits?
Apple, pears, grapes
How are called the leftover skins and stalks from winemaking?
Pomace
What are the 3 spirits made from pure sugar cane?
Rhum agricole, Cachaca, Kokotu Soshu
What is “modification” in a grain?
Releasing the starch granules from the protein net
What is “gelatinization”?
Solubilization of the starch granules with the help of water/heat
How is called the break of the weak bond between glucose molecules?
Enzymatic Hydrolysis
What is Kilning?
Process by which the germinated grain is dried and heated
How do you call the milled malted barley?
Grist
What happens during malting?
Modification and enzyme release
What is mashing?
soaking grist in water (63°-64°) to allow gelatinization and enzymatic hydrolysis
How long does mashing take?
1 hour
How do you call spraying (twice) the solids filtered out to extract last bits of starch/sugars?
Sparging
What is a wort?
The sugary liquid ready to be fermented
What do we call a “distillers malt”?
A malt pale in colour caused by the low temp at kilning: preserves starches and enzymes for a maximum potential alcohol produced
What do we call a “specialty malts”?
Malt receiving more heat during malting creating darker colored grains leading to heavier flavors
What country accepts Exogenous enzymes for its whiskey?
America
What is a fructan?
A complex carbohydrates made predominantly with fructose, especially found in agave
What are the 2 advantages yeasts have over other microbes?
They survive in acidic environments They produce alcohol that keeps other microbes away
What is the temperature operational range of yeasts?
10°C - 30°C
What is the time range for a full fermentation?
24h to 1 week
What are the two main roles of bacterias
Malolactic conversion Flavour creation
What is reflux?
Heat exchange between droplets and gas tends to concentrate ethanol in gas and water in droplets. This effect over time is called rectification
What is an “Azeotrop mixture”?
A liquid that reached a point when its droplets and gas have the same water/alcohol composition (97.3% abv)
What is the composition of Group 1 fraction?
Methanol and others compounds (Unpleasant, solventy, shooting and painful for the nose)
What is the composition of Group 2 fraction?
Ethanol mainly plus other fractions
What is the composition of Group 3 fraction?
Fusel alcohol (plastic, feet, cheese aromas)
What is the composition of Group 4 fraction?
Liquid to heavy to boil and never leaves the still. Generally acidic.
On a higher still, do we get more or less reflux?
More, leading to a softer spirits with less group 3
Do we get more or less reflux with a hotter heat input?
Less
What is the role of Dephlegmator/head condensers
To manage temperature at the top of the still. Allow lighter or heavier fractions to pass through
What is the Maillard reaction?
Caramelization/burning reaction happening when a sugar reacts with an amino acid. These reactions can take place in a still creating new flavours.
Would distilled wines on lees get more or less Maillard reaction?
More
What is the main chemical property of copper
It neutralizes sulfur
What are the main purpose of the first pot distillation?
Removing water Discarding group 4 fractions
What are the two principal aims of distillation?
Concentration and selection
What is the name of the mixture of gas and tiny liquid droplets that rises up from a boiling liquid?
Vapour
What is the boiling point of pure ethanol at standard atmospheric pressure?
78.3°C (173°F)
What is rectification?
The cumulative effect of reflux. In distillation this is used to refer to the increasing level of ethanol in the vapour. A spirit that is distilled to a higher abv than another one is said to be ‘more highly rectified’.
How is the boiling point of Group 4 fractions compared to the boiling point of fractions in other groups?
The boiling point of these fractions is very high and they do not come over during distillation.
What type of molecules have very pronounced, unpleasant aromas, even at relatively low levels of concentration, and cannot be easily separated from a spirit using cuts?
Sulfur-containing molecules.
Name two materials are used in the construction of stills to manage the levels of sulfur-containing molecules?
Copper and clay.
What is the boiling point of pure water at standard atmospheric pressure?
100°C (212°F).
List 3 ways of managing reflux
Manage intensity of the boil
Use of plates
Use of dephlegmators
What is the role of a sugar seed crystal?
To act as an anchor point for sucrose to crystallise
What are the two aimes of cooking grains (other than barley)
Breaking the protein net and genalinisation
