The article was prepared based on materials from the book “Fundamentals of Whiskey Technology” Makarov S.Yu. and discussions on the forum
One of the main differences between the technology of distilled drinks (whiskey, cognac, Calvados, etc.) and our classic moonshine is long-term aging in barrels. Barrels can be made from various types of wood, both deciduous and coniferous. However, as it has been established over time, almost all types of wood either have a negative effect on the quality of whiskey, enriching it with undesirable components, or are unsuitable for long-term storage of liquids due to rotting. Only oak wood has high strength and a lower amount of resins compared to other types of wood and does not give off excessively strong third-party aromas.
Overall, buying a barrel is no less complex issue than choice moonshine still. It is impossible to list all the factors influencing the final choice. Everyone has their own. I bought my first oak barrel spontaneously. I already bought the second and third ones consciously. I chose them based on the following parameters:
Displacement.
How many liters of barrel do I need? If you take a small one, it will run out quickly. At the same time, the aging period will not allow you to quickly replenish the need for the drink. If you take a large one, will you be able to fill it so as not to keep it half-empty or, God forbid, completely empty? A balanced assessment is needed between the amount of moonshine produced and the amount of moonshine disposed of.
Note (source of information - post on the forum )
According to experts, the quality of the drink depends on the volume and shape of the barrel: alcohol in small barrels with a larger specific surface area matures much faster than in large ones, but the latter give a higher degree of oxidation of whiskey. All over the world, the standard for 1 year of aging of an alcoholic drink is its aging for exactly 12 months in a 200-liter barrel. Aging in barrels of other sizes differs in time. Without going into details why, I simply present the table itself, which indicates the volume of the barrel and how many days it takes to achieve 12 months of aging of the product in a standard 200 liter barrel:
1 liter - 58 days
2 liters - 80 days
3 liters - 90 days
5 liters - 105 days
10 liters - 134 days
20 liters - 173 days
200 liters - 365 days
Was sawn or split oak used in the production of staves?
In the production of oak barrels for alcohol producers, the “chopped oak” technology is used. It is more expensive, but allows you to get better quality barrels. For home distillers, there are barrels made using the “sawn oak” technology. They are cheaper, but lower quality. This is exactly what I bought for the first time.
With or without tap?
I prefer without a tap. An extra hole through which leaks are possible. Although for decorative use it is certainly more beautiful with a faucet. How to drain without a tap finished product? I use a hose.
Where to buy?
But under no circumstances rely on the price. Buy only on the recommendation of users who are not interested in selling. Ask a question where is the best place to buy in any group about moonshine on a social network.
Preparing the Barrel for Operation
A new oak barrel must be prepared before use. No glue or nails are used to make the barrel. The barrel consists only of oak staves, which are very carefully selected in size and held in place by metal hoops.
There may be natural gaps between oak staves that are invisible to the human eye, but significant for liquids that can leak through these gaps. Therefore, the barrel soaking procedure is the process of eliminating small gaps between oak staves to make the barrel airtight.
The soaking process occurs as follows: pour the full volume of ordinary water into the barrel, change the water every 2-3 days so that it does not “go stale.” This must be done until the oak barrel stops flowing. At the beginning of soaking, the water will be dark brown in color - this is the result of the extraction of tannins. Their concentration must be reduced until the water in the barrel becomes clear. Dark brown water at the beginning of soaking is natural dye. Therefore, it is not recommended to carry out the soaking process in expensive baths, which can be stained by tannin.
As a rule, complete elimination of leaks occurs within 2-3 weeks, but this process can take up to 4 weeks. After the oak barrel stops flowing and the water in it becomes clear - oak product ready for your first use.
The theory of aging in oak barrels
Making barrels
To make barrels, wood is selected between the core and sapwood of trees, devoid of large knots and twists. To make staves, oak is not sawn, but split along the grain of the wood to provide greater strength and water resistance, and then planed by hand or on machines into even boards (staves). The yield of split staves from the commercial part of oak does not exceed 18-22%. The staves are laid out in the open air, where they are aged (ripened) in stacks depending on the climate for 1.5 to 3 years (in France - up to 5) without sheds for drying and eliminating the unwanted bitter taste of raw wood and muting the “oak” tones . After curing, the rivets are finally given the desired curved shape of the side surfaces by cutting out patterns. The barrel frame is assembled like a fan onto one end working hoop. Next, to ensure better flexibility of the rivets, the wood is subjected to heating (firing) with periodic moistening of the surface. The degree of burning, which can vary from mild to severe, depends on the time of contact with fire. Despite the differences in the technology for preparing barrels, and, as a consequence, the different organoleptics of the future drink, the main goals achieved after roasting are approximately the same:
degradation of wood polymers to produce aroma compounds;
destruction of unpleasant resinous compounds found in wood;
charring the wood and creating a layer of pure carbon on the surface.
Under the influence of fire, the wood changes its structure, the sugars it contains are caramelized, and some aromatic components are released, which will appear in the drink as hints of vanilla, coffee, toast, and spices. The content of furan aldehydes in the wood increases, mainly furfural, phenoaldehydes (vanillin, syrinaldehyde), (3-methyl-y-octalactone. The finished barrel is re-fired, which gives the drinks in it a characteristic aroma of fresh bread crust, caramel, roasted almonds. Firing significantly speeds up the process of maturing whiskey and, although the total amount of tannins extracted decreases, as a result of enrichment with the components of the breakdown of wood substances, higher quality alcohols are obtained.
Type and quality of oak affect the organoleptic properties of the final product. Therefore, trees no younger than 40 years old are used. For endurance the best varieties trunks are selected that are between 100 and 200 years old.
The substances included in the wood enrich the bouquet of the drink, it becomes complex:
Two types of lactones, which appear when the wood dries, are responsible for the oak and coconut aromas in the aged drink;
Vanillin is obtained by firing the barrel, but high temperatures can reduce its level;
Thanks to guaiacol, formed when lignin breaks down under the influence of fire, the drink acquires a smoky aroma;
If spicy, clove notes are felt, then this is the influence of volatile phenol-eugenol. It is released when wood is dried, but is reduced by firing;
Furfural appears during the dehydration of hemicellulose pentosugars at high temperatures and gives the drink shades of creamy toffee, almond, and fresh bread.
In general, gas chromatography analysis of oak wood yields about 100 chemical components.
There are about 300 species of oak in the world, but only three of them are suitable for cooperage:
Sessile oak (Quercus sesstiis)
English oak (Quercus peduncolator)
North American white oak (Quercus alba)
On a note
French oak is currently considered the best. Its wood is not only very aromatic, but the very subtlety of its aromas is considered unsurpassed. However, this wood is the most expensive on the market.
Slavonian oak is exclusively a variety (Quercus peduncolator). The structure of its fibers is somewhat coarser than that of French. The main suppliers of these breeds are Hungary, Romania, Ukraine and Russia.
Wood American oak differs in significantly greater hardness. Most of the oak used to age whiskey these days is grown in the United States.
The barrel consists of a round frame, somewhat convex in the middle, and two flat bottoms - end walls. The frame and bottom are assembled from separate planks. The frame of the barrel is tightened with galvanized steel hoops, which ensures strength and tightness; no glue or nails are used, as they will affect the taste of the drink. The bottoms are firmly held in the frame of the barrel by their beveled edges on both sides, which fit into grooves on the inner surface of the frame, called chimes. The middle, most convex part of the frame is called the bunch. The diameter in a bunch means the diameter of the largest section of the barrel.
Service life of an oak barrel
During their operation, barrels take an active part in shaping the consumer properties of drinks, and, consequently, they age and, after a certain period of time, become unsuitable for further work and “die.” The aging of oak barrels has not yet been studied, however, qualitative changes consist of the leaching of individual chemical components and a change in the porous structure of the stave; the inner surface is noticeably destroyed.
Barrel Upgrade
Multiple reuse Infusion barrels give unsatisfactory results due to depletion of extractive substances, so they can be regenerated. The inside of the barrels is cleaned with metal brushes or mechanical devices, and then recharred with gas burners. In this case, changes in lignin and polysaccharides similar to the first firing occur. However, other components of the wood may not be regenerated, so the drink aged in such barrels will vary greatly in quality and most of the whiskey matured in such barrels is used only for blending.
Existing styles of aging in oak barrels
With the exception of whiskeys made in the US and Canada, very little whiskey is put into new barrels. Most barrels previously contained other spirits or wines. According to some winemakers, whiskey matures better in used barrels, their first aging removes the most obvious "woody" flavor from the wood, while adding its own desirable flavors to the spirit or wine. Other experts, on the contrary, argue that new charred barrels give the drink a better bouquet and help accelerate ripening. In any case, it is obvious that the choice of barrel is determined by the food traditions of the country of origin and style, of which the following can be distinguished.
Scots-Irish style.
Whiskey is aged in oak barrels up to 700 liters (usually 180-500) for at least 3 years. Infusion is carried out in used bourbon (charred) or sherry barrels. The oak reserves of these countries are very limited, so initially this was done to reduce the cost of purchases, since in the USA (bourbon) and Spain (sherry) barrels are not reused. However, it turned out that such barrels gave whiskey a new quality, and marketers included used barrels in the whiskey legend being created in those years. Spanish sherry casks are considered the most suitable. The filmy sherry yeast "yogi" (Saccharomyces ellipsoideous), living on the surface of the wine, not only absorbs the sharpest part of the oak extractives, but also adds other oxidation products of the wine, which are then transferred to the whiskey. Since sherry casks are in short supply, American white oak casks that previously contained bourbon are used.
American style.
Aged only in new, heavily charred oak barrels. According to one legend, such barrels began to be used when, after a fire in one of the warehouses, it was necessary to age whiskey in partially burnt barrels; this improved the quality of the drink so much that the next time they began to fire them from the inside on purpose. According to another version, fish barrels were used, which were deeply fired to get rid of the fishy smell. The barrels were filled with straw and set on fire, this deodorized them and killed most of the microorganisms on the walls. Be that as it may, deeper firing of barrels allows you to somewhat speed up the ripening time of the drink, strengthens the walls, protecting them from rotting, and disinfects the surface layers seeded with microorganisms during the maturation of the stave. The resulting whiskey has a sweetish taste and a beautiful golden color, and the specific corn smell disappears. After the drink has matured, the barrels are not used again in the USA, but are sold to the countries of the Old World and Canada.
Canadian.
For aging, oak barrels are used, both new and used for bourbon, sherry, and fortified wines. The volume of barrels is up to 680 liters. The aging period is at least three years. Three-year aging became mandatory only in 1974, and before that, according to the law of 1890, whiskey was aged for at least two years.
Processes that occur during aging in a barrel
Unaged whiskey contains more than a thousand different components in its bouquet, and, as a rule, has mediocre organoleptic properties. It is during aging in oak barrels that whiskey reaches its final bouquet; this is the longest operation, so aging can be considered the main operation in which alcohol with low organoleptic properties becomes whiskey, which at the same time acquires characteristic color and flavor-aromatic properties, darkens, the taste becomes softer and additional aromas appear. Despite the fact that many reactions that take place during aging in oak barrels have already been described, there is still no complete understanding of the chemical and physical processes that occur during this process and, perhaps, the only way to assess the quality of aging remains organoleptic.
Changes in the organoleptic properties of the drink
During aging, reactions occur that form new aromas, and vice versa, removing other chemical compounds. In any case, during aging the taste and aroma characteristics of the product should improve. By “mature” aromas we mean vanilla, spicy, floral, woody and soft. “Coarse” and “immature” odors include sour, grassy, oily and sulfurous odors. The degree and speed of changes in organoleptic properties during aging depend on the type of barrels. Clyne J. (1993) has shown that charcoal filtering whiskey prior to aging enhances the intensity of “mature” characteristics such as “softness”, “vanilla” and “sweetness”, and reduces the intensity of “immature” characteristics (“harshness”, “acidity” and “oilyness”), and conversely, the use of already used barrels reduces the intensity of the “maturity” characteristics and increases the intensity of the “unripe” properties.
Changes in chemical composition during aging
From a chemical point of view, the distillation process is decisive for the isolation of volatile compounds from the mash, and aging in barrels affects mainly the content of non-volatile compounds. However, some volatile compounds undergo significant changes during aging, which are associated with the type of barrel. During aging, color, pH, total solids, acids, esters and sugars change, and the taste and aroma of the final product is affected by the combination of all of the above components.
During ripening, a lot of different reactions take place simultaneously, the products of which, in turn, react with each other, but they can be conditionally divided as follows:
1) direct extraction of soluble wood compounds;
2) decomposition of wood substances, such as lignin, cellulose and hemicellulose with the formation of soluble substances extracted with an aqueous-alcohol solution;
3) chemical interaction of wood substances with distillate substances;
4) reactions in which only soluble wood substances participate;
5) reactions in which only distillate substances participate;
6) evaporation of volatile substances of the distillate, both through the wood layer and through the micro-leaks of the staves;
7) formation of stable hydrates of ethanol and water, as well as hydrates of other distillate substances.
1. Direct extraction of soluble wood compounds.
In barrel wood, the main types are formed as a result of the breakdown of polymer compounds of wood (lignin, cellulose and hemicellulose), both directly in the thickness of the staves and after their extraction with an aqueous-alcohol solution. Oak wood consists of 45% cellulose, 15% hemicellulose, 30% lignin and 10% extractable fractions (essential oils, volatile and non-volatile acids, sugars, sterols, tannins, dyes and inorganic compounds). Despite the relatively small number of extracted fractions, they have a major influence on the aged drink, and their composition depends on the type of wood, on pre-treatment and on how many times the barrel has already been used for aging drinks. In general, more tannins and less lactones and scopoletin are extracted from European oak wood than from American oak, but this alone cannot explain the differences in the organoleptic properties of whiskey when aged in one or another barrels. Such differences are only partly related to the wood of the barrels - they are also influenced by different barrel manufacturing technologies.
The firing of barrels, so common in the United States, is one of the reasons for the specific aroma of bourbon (a rich creamy floral bouquet combining aromas of toffee, chocolate, vanilla, honeysuckle and anise, taste grainy taste with tones of candied fruits, nutmeg and spices). When the inner surface of barrels is pyrolyzed under the influence of fire, a layer of coal is formed and the release of lac-tones, coloring and phenolic extracts from oak wood increases significantly. The main factor in increasing the content of phenolic extract is the decomposition of lignin to aromatic compounds - vanillin, lilac, pine and mustard aldehydes. During aging, these compounds are extracted with alcohol, and further decomposition of lignin occurs through oxidation and hydrolysis. When barrels are used repeatedly, the extract content decreases each time. With a decrease in the extract content, the development of such properties inherent in ripened drinks as “softness”, “vanilla” and “sweetness” is also reduced, and the degree of suppression of “unseasoned” properties - “soapiness”, “oilyness” and “sulfur content” is also reduced. Naturally, there comes a time when the barrel exhausts its capabilities to improve the organoleptic properties of the drink and it is recognized as “exhausted resource.”
2. Decomposition of wood substances with the formation of soluble substances extracted with an aqueous-alcohol solution.
Among the substances extracted from wood, the largest quantities are tannins, lignin, reducing sugars, and to a lesser extent amino acids, lipids, volatile acids and oils, resins, and enzymes. At the first stage, the extraction of the most easily extracted tannins and their intensive oxidation, hydrolysis of hemicelluloses and the appearance of xylose, arabinose and glucose, and the formation of furfural occur. At the next stage, the extraction of tannins weakens, but their further oxidation occurs.
3. Chemical interaction of wood substances with distillate substances.
The maturation and aging of alcohol is accompanied not only by the extraction of oak components and their chemical transformation under the influence of oxygen, but also by the interaction of these compounds with each other and with alcohol. Typically these are esterification reactions, but theoretically they can also include oxidation and acetylation reactions. During aging, due to the esterification of free acids with ethyl alcohol, the concentration of esters increases. Lignin and the products of its transformations play a decisive role in the formation of the taste and aroma characteristics of the drink. During long-term storage of alcohol in oak containers, ethanolysis of oak wood occurs and the alcohol is enriched with ethanol-lignin. Alcohol acids, the content of which increases slightly as the alcohol ages, enhance the ethanolysis of lignin. Ethanol-lignin serves as a source of formation of coniferyl and sinapic alcohols, which, under the influence of oxygen, are converted, respectively, into coniferyl and sinapic aldehydes. Further oxidation of these substances leads to the formation of vanillin, lilac aldehyde and other components of whiskey, which have a specific pleasant aroma and participate in the composition of its high organoleptic properties.
4. Reactions in which only soluble wood substances participate.
As a result of the oxidation of polymer compounds of wood and whiskey, the taste of the resulting drink improves. Thus, during the oxidation of tannins, the taste softens, the roughness and harshness in the taste disappears ("oak tones"), as a result of the oxidation of oak wood lignin, aromatic aldehydes and acids are formed and extracted into the aged drink, which mainly determine the organoleptic properties of the alcoholic drink . When carbohydrates are oxidized, compounds of the furan series (furfural and its derivatives) are released into solution, which also determine the taste and aroma of the resulting drink. The formation of Molactones, which are also aroma-forming compounds, is associated with the oxidation of wood lipids; it is also likely that these compounds can be formed during oxidation fusel oils, aliphatic acids. Oak wood contains quite a lot of tannins (about 1% in American white oak and 8% in Spanish or French), which are the most extractable substance. There are also lignins, vanillin and wood sugars, which caramelize when the barrel is fired, giving the contents, in addition to color, a sweetish taste and aroma. Oak enriches the drink with hemicellulose, tannins, lignins, polyphenols, dyes and aromatic organic acids (for wines and spirits aged in new oak barrels, the smell of vanilla is especially characteristic).
5. Reactions in which only distillate substances participate.
Changes in the properties of the distillate during aging may be caused by the loss or suppression of aromatic compounds due to the evaporation of low boiling point compounds through the wood, their adsorption to the surface of the barrel, or a chemical reaction resulting in a decrease in the content of volatile compounds in the whiskey, or a change in its organoleptic properties.
Chemical reactions that influence changes in the content of components in the distillate include oxidation and acetylation reactions. Examples of the former are the formation of acetaldehyde and acetic acid from ethyl alcohol, as well as the formation of dimethyl sulfoxide from dimethyl sulfide. Oxidation reactions during aging are enhanced in the presence of wood extracts, especially vicinal hydroxyphenols, which, along with trace amounts of copper from the distillation apparatus, act as catalysts.
6. Evaporation of volatile substances from the distillate, both through the wood layer and through the micro-leaks of the staves.
Most intense change chemical composition whiskey occurs in the first year of aging. The content of titratable and non-volatile acids, extract and tannin increases especially quickly. The content of aldehydes and fururol remains practically unchanged in the first year, and then the rate of their formation increases. The amount of esters increases evenly throughout the entire storage period. The content of higher alcohols increases slightly. The color and extract increase almost uniformly. In general, the concentration of most volatile components increases due to the evaporation of alcohol and water during storage (natural "concentration"). But a sharp increase in esters and aldehydes occurs due to other reactions.
Oak wood belongs to colloidal capillary-porous bodies, in which the movement of liquid is determined not only by diffusion-osmosis (impregnation), but also by capillary forces. During aging, the strength of the alcohol changes and the volume of the drink decreases due to evaporation through the pores of the barrels.
7. Formation of stable hydrates of ethanol and water, as well as hydrates of other distillate substances.
Whiskeys consist mainly of ethyl alcohol and water, and the compounds involved in the formation of aroma are present in very small quantities. Also D.I. Mendeleev showed that ethyl alcohol and water at different ratios do not form a homogeneous mixture; at high concentrations there is an excess of free alcohol molecules, and at low concentrations there is an excess of free molecules of water. Only at low concentrations of ethyl alcohol (less than 17% vol.) does it completely form hydrates when combined with water. This aggregation of ethyl alcohol molecules increases the solubility of hydrophobic aromatic compounds, which, in turn, affects their release into the headspace above the drink.
The influence of various factors on the characteristics of the drink during aging
The properties of the infusion barrels have the greatest influence on the properties of the drink, but storage conditions, infusion time, etc. also play a certain role.
New charred barrels.
Maturation in new barrels imparts intense color and flavor, often completely masking the original bouquet of the distillate. Aromas described during tasting: wood, vanilla, coconut, resinous, pine, cedar.
Sherry casks.
They impart aromas typical of sherry to the whiskey: a combination of vanilla, fruity and sweet aroma. Despite the mild heat treatment, alcohol matured in such barrels gives a fairly intense color and aroma.
Bourbon barrels.
Characterized by a dry, earthy, fragrant and vanilla aroma. Changes the properties of the distillate quite well compared to sherry casks.
Used barrels.
Reuse of barrels leads to a decrease in compounds extracted by alcohol, the maturity of the drink occurs later, and the ability to mask soapy, fatty and sulfuric aroma is reduced. All compounds extracted from wood by alcohol are retained, but at a much lower level, and their ratio may also change. The evaporation process takes precedence, which inevitably affects mature whiskey. If bourbon or sherry were previously infused in barrels, their influence on the bouquet of the drink is almost unnoticeable.
Reclaimed barrels.
Used barrels are restored for subsequent aging by scraping off the old char layer and re-firing. Regeneration does not completely restore all components of the wood, but the levels of extractable substances are higher than in used bourbon or sherry casks. During firing, pyrolysis products of lignin and wood polysaccharides again appear. On the other hand, oak tannins and lactones, extracted by previous infusion, can no longer be extracted, although they are present in small quantity. The ability to mask unpleasant aromas and tastes of whiskey is also restored.
Barrel sizes.
The size of the barrels varies from 500 liters (bottles) to 191 (standard American) or even 45 liters (octaves). According to the legislation of most countries, their capacity cannot exceed 700 liters. The shape of the barrel may differ from the traditional “barrel-shaped” one; for example, Spanish port wine barrels are cigar-shaped. The smaller the barrel, the greater its ratio of internal surface area to volume, due to which the extraction of compounds from wood occurs faster, but at the same time ethyl alcohol and water evaporate faster. If we compare barrels made of the same wood and the same “history”, then in smaller barrels the degree of extraction of wood components will be higher, and aging of whiskey will require less time.
Exposure time
is an important factor in the maturation of the drink. It is not uncommon to mature within ten to twenty years. It is quite difficult to identify any clear patterns in changes in the quality of the drink due to the many factors affecting whiskey; the processes practically cannot be simulated in the laboratory. The change in color during the first and second filling occurs, as a rule, during the first six to twelve months, after which the rate of pigment extraction decreases, but does not become zero. In used barrels this effect is not so pronounced and the color increases throughout the aging process. In the latter case, increasing the aging period undoubtedly affects the development of mature flavors of the drink. Of course, aging in used barrels requires more time, due to a decrease in the amount of extracted substances, this explains the three-year period for Scotch and Irish whiskeys (actually much longer) versus two years for American and Canadian whiskeys matured in new barrels. The optimal aging periods for wines and spirits in different climatic conditions were empirically determined. Thus, tequila producers have come to the conclusion that aging in barrels for more than 7-8 years makes no sense - firstly, a significant part of the volume is lost, and secondly, woody tones begin to dominate in the drink. Therefore, rums and tequilas - drinks from countries with hot and dry climates - are rarely kept in barrels for more than 10 years. In cool and rainy Ireland, Scotland and France, whiskey and cognac can live in barrels for 20, 30 and even 60 years, but those examples that have benefited from such longevity are the exception rather than the rule. Usually very old spirits as a result of prolonged contact with a barrel completely lose their individual characteristics, turning into an alcoholic extract of oak wood. Therefore, throughout the entire maturation, samples are taken from the barrels for tasting to exclude the possibility of “over-ripening” the whiskey.
Initial strength of raw whiskey.
Distillates are poured into barrels at a strength of 57 to 70% vol. (American whiskey - up to 62.5% vol.) for malt whiskey and up to 80% vol. for grain. Strength directly affects the character of the future drink. Low - promotes the preferential extraction of water-soluble compounds, such as hydrolyzed polyphenolic substances, glycerol and sugars. High alcohol content removes alcohol-soluble substances such as lactones, which subsequently create problems during filtration, reducing the content of coloring pigments, solids and volatile acids. A strength of 60% vol. is considered optimal for the extraction of dry substances, but this does not at all mean the best organoleptic characteristics of the drink. When choosing a strength, you have to take into account the climatic conditions of storage and what process occurs: strengthening or reducing the alcohol content. American practitioners, for example, consider the most favorable concentration to be up to 50% vol., since this not only accelerates the maturation process of whiskey, but also minimizes losses from evaporation.
Premises for storing whiskey during maturation.
The distillate loses alcohol, volatiles and water. These inevitable losses are called the “angels' share” and, depending on storage conditions, range from 1.5 to 7% of the total volume of distillate per year, although over time the evaporation process slows down somewhat. Losses of volatile substances also vary by geographic zone: in countries with dry and hot climates (Mexico, USA) they can be large, in England with its cool and humid climate they decrease. The rate at which the volume of liquid decreases depends on many factors: the type of oak from which the barrel is made, what kind of drink was previously in it or the barrel was new, the size of the barrel, the number of times this barrel was used to age whiskey (usually a barrel is not used to age whiskey more than three times), alcohol strength, temperature and humidity in the storage, and their differences depending on the geographical location.
Depending on the external temperature and humidity, both a decrease in the strength of the distillate and an increase in it can occur due to the predominant evaporation of water rather than alcohol. It is believed that if the relative humidity is below 70%, then the rate of evaporation of water exceeds the rate of evaporation of alcohol. At humidity levels above 70%, preferential evaporation of alcohol will occur. At 70%, the evaporation rates of water and alcohol are equal, in this case there is a decrease in the volume of the drink without a decrease in strength. Air exchange in storage also plays a great role in increasing losses: in well-ventilated rooms or when storing under canopies, losses are higher. Evaporation through leaks in the barrel staves should also be taken into account. Of course, the temperature in warehouses is of great importance, accelerating not only evaporation, but also all chemical reactions. Higher temperatures speed up the extraction of barrel substances and the overall maturation of the drink. Maturation at high temperatures, which accelerates the rate of diffusion processes, produces whiskey that is darker, sweeter, but with more impurities and less pleasant than at low temperatures.
In general, the influence of such parameters as temperature, humidity, ventilation intensity and pressure in barrels on the quality of whiskey is not precisely known. Therefore, there are no scientifically based recommendations for the design of warehouses; their designs are developed primarily on the basis of traditions and experience.
How long does an oak barrel last?
To such a frequently asked question, we can safely answer that the barrel definitely has its own resources, which are depleted over the years. Also, the tannins that the barrel itself possesses simply disappear over the years.
If you don't put in much effort, the barrel can last 15-20 years. But if you care for it properly, its service life can be significantly increased. Basically, it is aged approximately 6-8 times in one barrel. Then it is advisable to completely disassemble the barrel and burn it from the inside; of course, the effect and benefit will be slightly less than from a new barrel.
How to increase the service of a keg?
In order for a new barrel to last as long as possible, careful care is required. For example, the service life of an oak barrel for moonshine can be increased as follows. Moonshine is not known to be aged in oak barrels for many years. Rather, they keep it for several months. On average, a barrel lasts about 15-20 years, which means that the barrel can be used repeatedly for moonshine. The main thing is to lubricate the barrel with beeswax while aging an alcoholic drink; this will prevent the drink from evaporating and will also strengthen the oak barrel itself. In addition, after each use of an oak barrel, it is necessary to wash it thoroughly and then dry it. And then fill it again with some liquid. You need to remember once and for all: an oak barrel cannot be left empty, as it may dry out. Even if the entire procedure of soaking the barrel has been completed, and then after a single use, the barrel remains unfilled for a long time, it will begin to leak liquid.
After use, the barrel should be filled with lime (quicklime), then pour boiled water, leave for about four hours, drain the water, fill ice water, repeat this procedure several times. Finally, fill with warm water and place in a dark place. Only in this case will the keg be stored in the necessary conditions.
When an oak barrel is used to age and store cognac or wine, the product can age for several years. During this time, the barrel loses some tannins, which you need to try to restore; this can be done by roasting. We disassemble the barrel, burn it from the inside, and put it back together. This way you can slightly extend the service life.
When a barrel is needed for pickling products such as cucumbers, tomatoes, mushrooms and other pickles, which are pickled in brine for one or several seasons, then the process of its processing is similar to the processing after aging moonshine. The barrel should be thoroughly washed, dried, and then soaked and filled with liquid.
So, not all barrels can serve for many years, mostly 15-20 years, but if you give it proper attention and care, you can extend its service life by several years. And with the help of ordinary disassembly, roasting, and assembly of the barrel, you can even try to preserve its tannins. After all, they are the ones who give alcoholic drinks and pickles that extraordinary taste.
The quality of long-term aging of the distillate is not an idle question for any home winemaker. It is only possible by aging moonshine in an oak barrel, which, interacting with the drink, will add a tart taste, an aromatic composition and a unique color. Homemade moonshine, after a certain time, turn into cognac or other noble alcoholic drink.
To infuse moonshine in an oak barrel, you definitely need time, high-quality preparation of storage containers, and compliance with basic requirements for the characteristics of the raw materials.
What strength of moonshine to pour into an oak barrel depends on two significant circumstances:
- oak barrel size;
- the expected aging time of the drink.
When saving alcoholic beverages at home, it is most logical to use small containers.
For oak containers with a volume of two to ten liters, you will need moonshine with a strength of 40-50%. In this case, the holding period should not be less than six months.
If necessary, withstand large quantity Moonshine (more than ten liters) requires a strength of 55-70%, and at least three years of time. The longer the barrel with its contents is stored, the stronger the final drink will be.
The quality of an alcoholic product directly depends on the frequency of use of infusion containers.
A barrel used for storage for the first time releases maximum wood components to the drink. With each subsequent time, the saturation of moonshine with oak extracts becomes less and less pronounced. After the fifth fill, the oak barrel is only a storage tank, as the wood will be depleted.
To obtain excellent results, the winemaker should follow the technology of aging moonshine in an oak barrel.
The wood of a new barrel contains too many tannins - tannins, the concentration of which needs to be reduced. If in an oak barrel without preliminary preparation pour wine or distillate, the alcohol will quickly become cloudy, then an unpleasant tart aftertaste will appear, which is popularly called “plinth”. Soaking a keg takes time, patience and a lot of water.
In home distilling, it is better to use barrels with a volume of 2 to 10 liters. The smaller the volume, the faster the wood releases tannins, which reduces the aging time. The reason is the area of contact with alcohol. For example, in a five-liter barrel, 1 liter of drink comes into contact with 400 square meters. cm of wood, and in a fifty-liter one - only 152 sq. cm. Accordingly, the ripening period of moonshine, cognac or wine in a large container increases significantly.
Barrels with a volume of 10 to 50 liters are only suitable for long-term aging strong drinks. During the ripening process, part of the contents evaporates through the pores of the wood. Regardless of the volume of the barrel, losses amount to up to 1 liter per year; in cognac production technology, this evaporation is called the “angels' share.” If you pour the distillate into a small barrel, after 5 years there will be almost nothing left inside.
I advise you to buy already waxed oak barrels. Waxing protects the wood from external factors, extending its service life, preventing leaks and making the barrel more beautiful. At the same time, the wax does not affect gas exchange, the drink continues to “breathe” normally through the pores. It is also desirable that the barrel be without a tap, since this is the most vulnerable element of the structure, which often gives a strong leak. At one point, all the contents may end up on the floor. For a beautiful presentation, it is better to buy a small barrel of 1-3 liters and pour the drink into it before guests arrive.
Crane - convenient, but dangerous! Barrel preparation technology
1. Fill new barrel fill 90% of the volume with clean, filtered water at room temperature, close with a stopper and leave for 3-4 hours.
2. Check the barrel for leaks by carefully inspecting the wood around the perimeter of the rings, then the bottom from the front and back. A slight leak is not critical; this problem will correct itself at the next stage, when the wood swells. The main thing is that there is no jet, since such a barrel is considered leaky and needs repair.
3. Fill the barrel to the top with water, close tightly and transfer to a room with room temperature. If leakage is observed, add water every 12 hours until the leak stops. After 3 days, drain the water (it will be a dirty brown or yellow color), then add a new batch of clean water.
The first water is the dirtiest 4. After a day, drain the water, add boiling water to the barrel (1 liter per 10 liters of volume), close tightly and rock the product from side to side several times so that the boiling water washes the entire inner surface of the barrel. After 45 minutes, fill to the top with water and close tightly.
5. After 24 hours, change the water again. The process of soaking the barrel (daily replacement cold water) repeat until the last water becomes clear, tasteless and odorless. This usually takes three to six weeks.
6. Boil water (50% of the volume of the barrel), then cool to 70-75°C, add soda (20 grams per 1 liter), mix and pour into the barrel. Shake vigorously for 8-10 minutes, then drain the soda solution.
7. Fill the barrel to its full capacity hot water, hold for 15 minutes, drain, and refill with clean cold water, which should be poured out after 8-10 hours.
8. If the barrel is intended for strong drinks (moonshine, cognac, whiskey, bourbon), the container is ready for use. In the case of wine, I recommend first keeping the distillate diluted to 18-20 degrees for 30-45 days double distillation without smell.
In addition to the volume of the barrel, the aging result is influenced by: air humidity (optimal 80-85%), temperature (10-12°C for wine, 14-16°C for strong alcohol) and infusion time. The process is monitored through periodic sampling. When the taste is satisfactory, the drink is poured into glass containers for long-term storage.
Alcoholic drinks aged in oak barrels acquire amazing taste properties. These products can literally breathe. Air penetrates the drink without obstacles, and alcohol vapor does not escape from the container. Oxygen reacts, increased oxidation of the contents and saturation with a pleasant smell occurs. Tanning oils on the inner surface give a new color to the moonshine and improve the taste characteristics. This article provides a description of how to prepare and ensure proper placement in a keg. A recipe for making whiskey is given.
Steaming the barrel
The process of treating the internal surface with steam is carried out for reasons of hygiene to remove bacteria from the wood and enhance its aroma. Heated stones are placed at the bottom of the barrel, and then water is poured onto them to a third of the volume. The barrel is sealed to preserve steam and kept that way throughout the steam generation process. After reducing the intensity of steam generation, the barrel is opened, poured with hot water and whipped with a fragrant broom. The remaining warm water poured from the barrel. After drying, the barrel is ready to be filled with alcohol.
Elimination of defects
New barrels may have very large gaps. A leak occurs as a result of improper preparation of an oak barrel. If the containers for 
strong alcoholic drink began to leak after transfusion, you should not wait until the gaps decrease naturally. Needs to be poured valuable product into another barrel so as not to lose it. The defective area should be dried. An ordinary household hair dryer is perfect for this. During processing, the device should be kept at a distance of 30-40 cm so that the temperature effect is not too hot and the oak barrels for moonshine do not deteriorate.
Barrel soaking
The container must be soaked before use. To follow the recipe correctly, you will need to pour boiling water into the barrel to 30% of the volume, and then close it tightly and hold the high temperature inside for half an hour. Then you need to rock the keg in order to wash the inside of the keg. After this, you need to carefully fill the tank warm water and change it once a day for two weeks.
How to store an empty oak barrel?
To prepare the container for storage, you need to correctly perform 
a few basic steps. Oak barrels emptied of alcoholic beverages should be immediately filled with cognac alcohol. Such tanks should be left full to prevent depletion. Alcohols suck a lot of substances out of barrels. This contributes to their exhaustion. It is not recommended to keep barrels empty for more than a day. They need to be used again.
What you need to know about barrel depletion?
Crafting Recipe good moonshine in an oak barrel depends on how many times the device has been used before. After the second, third and subsequent pours of young alcohol, due to the decrease in wood components, the rate of their extraction gradually slows down. This happens until the wood is completely depleted. After this, the tank can only serve as a vessel, and not as a source of useful components for alcohol.
How to age moonshine in an oak barrel?
When aging alcohol in barrels, all conditions must be observed. From this 
The process of development of taste properties depends. The alcohol obtained by distillation has a sharp taste and almost no color. With long-term aging, the components of the alcoholic drink change, a golden color appears, the taste softens and a pleasant aroma appears. The taste improves over time if you continue to infuse the drink. The alcohol becomes softer, and a subtle, pleasant flavor bouquet with a hint of vanilla, characteristic of well-aged drinks, harmoniously develops. You need to leave a little emptiness inside. This will promote the development of oxidative processes.
How to make whiskey from moonshine at home?
What ingredients are needed to create whiskey? How many do you need? 
A simple recipe is given as an example.
Required ingredients:
- 3 liters of moonshine 45%
- 3 tbsp. l. oak bark
- 50 g charcoal
- 6-8 dried apricots
Oak bark is sold in pharmacies. Coal is created by the elementary method of burning birch, oak logs or fruit trees. Choose wood that does not contain resins.
Recipe:
- The strength of moonshine should be increased to 45%.
- Charcoal is ground into powder.
- Oak bark, dried apricots and coal are added to the jar. One and a half liters of alcohol is poured into a jar and everything is thoroughly mixed. After this, the jar is filled. The container must be filled to the brim with moonshine.
- Good aging will be achieved if you place the workpiece in a cold room without light for two weeks, having previously closed it tightly.
- To get rid of wood residues, the resulting whiskey is filtered.
Storage conditions for finished alcohol
In order for a strong alcohol recipe to be executed perfectly, will it be necessary to maintain the optimal storage temperature range? from 14C° to 20C°. Suitable temperature is 16C°. If the specified temperature is violated, the loss of alcohol due to evaporation increases, and if 
decreasing, the aging process stops. Containers should be stored in dark basements without exposure to light and in the complete absence of vibration and any unnecessary odors. The humidity level should be at least 75%-85%.
Compliance with the above standards is mandatory. This is the only way to store moonshine in an oak barrel. To raise the humidity level, just place a basin or bucket of water in the room. You can cover the reservoir with something and place a small container of liquid under it. An easy recipe and the technology for preparing oak barrels is understandable even to beginners.
