Maturation Flashcards
Between production and packaging, all spirits undergo some aspect of maturation. Certain processes are quick, while others may be complex and take years. This deck covers them with a specific focus on oak maturation.
What is meant by the term ‘Angels’ Share’?
The part of the spirit that evaporates each year during oak/wood maturation.
What does ASB stand for?
American Standard Barrel
180-200L / 50-53 US gallons
Aside from drying outside naturally, where else can staves be dried?
In a wood kiln, which is much faster.
Besides flavors, aromas, and color, what else can a spirit extract from a barrel?
Tannins
Add bitterness or a grippy, drying effect on the palate
Define esterification
During maturation, which can take place in both wood and inert vessels, fatty acids and alcohols react with each other to form new esters.
For spirits destined for long aging, a distiller may intentionally leave a higher level of Group 3 fractions for added flavor development over time.
Evaporation can have a major impact on what?
The concentration of aromas and textures.
For an aging spirit, what happens to alcohol levels over time in a dry, less humid environment?
Alcohol levels rise in a spirit barrel.
In a dry environment, water is lost at a faster rate than ethanol.
For an aging spirit, what happens to alcohol levels over time in a damp, more humid environment?
Alcohol levels will fall over time.
In a humid environment, water evaporates more slowly compared to ethanol, and as a result, the alcohol by volume (abv) falls.
What is a Foudre?
A large wooden vat capable with a volume of 10,000 L / 2,641 US gallons.
What is a Hogshead?
Remade ASB barrel
250 L / 66 US gallons
How can the size of a barrel impact the extraction rate of color and aroma from the barrel?
The smaller the barrel, the higher the extraction rate, due to the ratio of the surface area of the wood to the volume of the liquid in the barrel.
How long can it take for staves to fully dry?
At least a year, but can take up to three years.
Examples of inert vessels:
- Glass
- Stainless steel
- Pottery
- Earthenware
Effects of maturation in inert vessels:
- Color will not typically change over time
- Flavors and textures will change after a few months or years, becoming smoother, richer, and more complex.
Oak alternatives
Oak fragments: chips, cubes, staves, mini-staves
The quality of oak flavor, lack of oxygen esterification, and poor concentration of flavors over time can be the result of the use of alternatives rather than barrels.
On a volume basis, how much spirit can be soaked up by an oak barrel?
There can be several liters of spirit absorbed into the barrel staves at any given time of maturation.
What causes oxidation?
Oxygen interacting with components of the spirit inside the barrel.
Oxygen interacting with components of the spirit inside the barrel can result in what?
Oxidation
What are pipones?
Very large barrels
20,000 L / 5,283 US gallons
What is preservation (maturation)?
- The practice of moving very old spirits into inert vessels in order to preserve them in their current state
- This is done for blending needs and other historical references
What is rancio?
A tasting term to describe the floral, nutty, dried fruit and pungent spicy / tobacco notes in long-aged spirits. It is indicative of oxidative aging.
What is re-barreling?
Moving a spirit from one barrel to another to get a different effect or build complexity, and can be used to slow down the extraction rate and not overpower a spirit with wood.
What volume does a Sherry Butt hold?
500 L / 132 US gallons
Size of a typical Cognac barrel?
300 L / 79 US gallons
The color a cask can give a spirit is dependant on what?
The type of heat treatment the barrel received.
i.e.: Charring can give more color
What are the five stages of barrel production?
- Cutting
- Drying - usually done outdoors
- Shaping/bending and heating
- Toasting
- Charring
The hottest part of an aging warehouse?
Top floors - heat rises.
The most commonly-used species of American Oak:
Quercus alba
White oak
The two important species of European oak?
- Quercus Petraea
- Quercus Robur
To what strength are spirits diluted before wood aging, and why?
Typically to between 60-63 % abv
Because high strengths will extract too many unwanted flavors from the wood due to the ethanol.
True / False:
A spirit sits passively inside an oak barrel.
False
A spirit is continuously moving into and out of the wood.
True / False:
Barrels are watertight, but not airtight?
True
Gases are able to move into the barrel, while components of the spirit are able to evaporate through the wood.
Typical aromas of Quercus alba?
Vanilla, clove, sweet spice.
What are some of the considerations for choosing an oak barrel to age a spirit?
- Species of oak
- Size of the barrel
- Age of the barrel
- Previous contents
- Fill strength
- Temperature
- Humidity
- Time the spirit will be in the barrel
What are the two broad categories of oak species?
Those native to North America and those native to Europe.
What are the two groups of interactions that oak can perform?
- Interactions between the spirit and the oak
- Interactions between the spirit and the environment
What are the two most important types of vessels used for spirit maturation?
Oak and inert vessels
What can a spirit left to age for decades be used for by a distiller?
Used in small amounts to add flavor or character to a blend.
What can heating the inside of a barrel do, besides imparting some flavors?
Can remove undesirable flavors.
What does drying the staves result in?
Drying removes water, as well as undesirable aromatics present in freshly harvested oak.
What does oxidation result in?
It produces a large number of new chemicals, many of which are aromatic and can play a big factor in the flavor of the final product, including adding rancio.
What is char?
A layer of carbon on the inside of the barrel, which has resulted from setting the wood on fire.
What is done to refresh a barrel for use?
The inside is scraped out to expose new wood, and then it is re-charred.
What is lost during spirit evaporation?
Mostly water and ethanol, but some other components may also be lost, such as Group 1 fractions.
What is one reason European oak may be less overt in the spirit than, say, the wood used for American whiskey?
The aromas are often restrained due to the use of a combination of new and used staves to build the barrels used for European-based spirits.
What is the basic result of time aging for a spirit?
Concentration of flavors and aromas, and more tannic.
What is the color progression of a spirit as it matures in oak?
- Clear
- Pale Lemon
- Gold
- Amber
- Brown
What is the definition or purpose of maturation?
Maturation is intended to make a positive change to the aroma, texture, and, in some cases, the color of the spirit.
What is the most commonly-used type of wood for distillery vessels?
Oak
What is toasting?
- The gentle heating of the barrel over several minutes, resulting in it becoming blackened.
- Most closely associated with European barrel production
What kind of interaction is char known as?
Subtractive
What kind of interaction is oxygen known as?
Interactive
What kind of spirits have vanilla, coconut, clove, and sweet spice aromas?
Wood-aged spirits
What kind of structure does the surface of charred wood have?
Irregular, and as a result, is able to remove/trap some of the components of the spirit, thus making it smoother.
What part of the tree is most important to the cooper?
The trunk, but not the sapwood.
What type of cellars does one find in Cognac?
Dry and Wet
In dry cellars, the alcohol levels go up over time resulting in an angular structured style of spirits, while the opposite happens in wet cellars, with a softer style of spirit being the result.
Where are staves traditionally dried?
Outdoors in order to dry naturally.
Where do the wood aromas come from in a barrel?
Some come from the wood itself, while others are a result of the heat treatment.
Where does the color, flavor, and texture of oak come from?
Molecules within the structure of the wood.
Which can impart more flavors: new or older barrels?
New barrels will impart much more flavor than used barrels.
Why are Bourbons typically aged in wood for a shorter period of time than Scotch Whisky?
Warmer temps in Kentucky increase the extraction rate of color and aromas from the wood, much quicker than in Scotland.
Why do spirits lose some volume each year in a barrel?
Because of evaporation.
Why is oak the most commonly used type of wood for distillery vessels?
- It is hard, durable, and sufficiently flexible to make into barrels, and it can be made watertight.
- It also imparts flavors that most people find agreeable.
Why would a distiller NOT use wood for aging their spirit?
Do not want oak flavors taking away from the purity of their spirit.
Inert vessels will be used - such as for vodka, fruit spirits, gins, Tequila Blanco, etc.
Wood polish and sweet spices are more prominent in which type of oak?
French oak
