Barrique wine, what`s the secret?

Using barriques is an art that requires deep understanding and skill, and can significantly enrich our wine experience.

Natural chemical evolution leads to the formation of complex chemical compounds that make the red color of the wine more intense and stable over time, which guarantees the softness and longevity of the wine.

History of the barrique barrel

The French word “barrique” means simply – barrel, but its meaning in the wine world was first narrowed down to only one, the mentioned type of barrel, but today it is much broader, extended to other shapes and volumes of oak barrels, and it also serves to indicate the care of wine in wooden vessels, the so-called “barricading”.

For thousands of years, wine was fermented, stored and transported in clay amphorae. The oldest archaeological finds are older than 8,000 years and come from Georgia, where amphorae are called “kvevri”. Wooden wine vessels were first mentioned by Herodotus in the 5th century BC, stating that in ancient Mesopotamia, wine was transported in them on ships along the Euphrates. But, apart from the fact that they are made of palm wood, nothing more is known about them.

According to most historians, the first oak barrels were used by the Celts, but not for wine. The first written mention of it comes from the time of the Roman conquest of Gaul in the 1st century BC, when Roman chroniclers recorded that the Gauls used oak vessels for their beer. The Romans adopted this practice for wine, and then spread it throughout the empire. Wooden vessels were incomparably safer than easily breakable amphorae, but they still remained in use for a long time due to easier stacking during transport on galleys.

Oak barrels came into widespread use at the beginning of the first millennium, primarily for practical reasons, but it quickly became clear to winemakers that oak has an extremely significant and very positive effect on wine. Already at the beginning of the Middle Ages, oak barrels replaced amphorae almost everywhere, except in Georgia, where they remained the main vessel for wine until today.

A French type of wine barrel of specific shape and volume, which varies from 225 l in Bordeaux to 228 l in Burgundy, dates back to the Middle Ages and is still in use worldwide today.

That traditional barrel of Bordeaux and Burgundy has been used only in France for centuries. The Italians, for example, only started using it in the mid-70s”.
(Text taken from: Salon vina Bgd.)

Types of oak

There are over 250 species of oak.
There are three main types of oak used for making barrels and barrels, which are used for wine barrels and oak products.

Quercus Robur  (Pedunculate), also called common oak, pedunculate oak or English oak, is one of two species from French and Eastern European forests. A faster growing species, its wood is rich in extractable compounds, including phenolics and ellagitannins, but low in B-methyl-Y-octalactone (fresh wood, coconut character). It has a high polyphenolic potential, it has wood rich in tannins, but it has few fragrant compounds and aromas. It is used for maturing wine and is well suited for brandy and cognac.

Quercus Petrae  (Sessile), also called sedum oak, is another species commonly used in French and European forests. A slower growing species, its wood is rich in B-methyl-Y-octalactone and low in ellagitannin. Barrels made of this type of oak provide a high aromatic potential for wine aging and have a low proportion of extractable ellagitannins.

Quercus alba  , also called American oak, grows relatively fast. The wood is characterized by the presence of cellulose and small amounts of ellagitannin, which enable slower oxygenation. The wood is rich in scopoletin, ferulic acid, B-methyl-Y-octalactone and B-nonalactone. Contributes to balsamic notes in wine, lactones and eugenol. It was traditionally used for bourbon and rum casks.

In the picture we see the anatomical structure of an oak tree. On the cross-section of an older tree or branch, starting from the outside towards the middle, the following are distinguished: bark, lika, cambium, pith, pith and pith rays.

Bark is dead wood that results from the death of a lichen. The thickness of the bark of an adult oak is from 2 to 3 cm.
The inner crust is similar . It is a thin layer created by the multiplication of cambium cells during the growth phase of the tree. It consists of conducting bundles through which organic juices circulate from the crown to the root system.

The cambium is a thin layer between the sapwood and sapwood. These are living cells, the reproduction of which makes the tree grow.
Sapwood is a living tissue through which, like the cambium, juices circulate from the root system to the crown. According to VIVAS, it is made up of about 10, and according to KELLER, 10 to 20 annual increments, the so-called. years.

There are differences within one year:
– the layer that forms in the spring (closer to the central part of the tree), is richer in conducting bundles consisting of large cells with thin membranes and a greater number of parenchymal cells representing the so-called spare tissue;
– the layer that forms during the summer (summer wood) is characterized by a smaller share of conductive bundles with smaller cells and a smaller share of parenchymal cells, and more fibers. That part is denser, darker, less porous and less capable of swelling.

The width of the grain is between 2mm and 2cm. Wood generally has better mechanical properties if there is less difference between the years in the anatomical structure and if summer wood dominates within the year. These conditions are better met by the oak tree.

The core consists of older years. This tissue is rich in lignin and impregnated with tannin. It is, in fact, a dead tree because there are no living parenchyma cells in it, nor are the juices circulating through it. That part is the most valued material for the production of wine vessels. With the exception of some plant species (willow, willow, etc.), the heartwood is lost over time and has no significance for the quality of the wood.

Core rays are visible to the naked eye in a cross-section of the tree. They consist of radially oriented prenchyma cells, whose physiological role is reflected in the establishment of connections and exchange of substances between the living layers of the tree.

Since the connection between them and the bundles of fibers is weaker than between the fibers themselves, the cohesion is weakened in those places, so it represents the preferential direction of wood splitting.

It is necessary to mention that good material for the production of wine vessels is obtained from straight trees, without knots, whose diameter at the top is not less than 30 cm. Cleavage is performed along the core rays. Sawn timber has poorer mechanical properties because sawing breaks the fibers, thus reducing its strength and elasticity.

The average age of the oak from which the barrels are made is 150-200 years.
The thickness of the oak tree from which the rainbows are produced is 50-80 cm
1 m3 tree → 0.2 m3 raw rainbows → 2 barrels and 2 dances
1 tree, 4 m long with a diameter of 80 cm → 2 m 3 → 4 barrels and 4 dances
40-70% is the moisture content of fresh oak
14-16% is the moisture content of ready-to-work rainbows
15-18 months is the period rainbow drying time
24 months average time needed for rainbow ripening
These are data from the largest and most famous French manufacturer of oak vessels, Seguin Moreau.

Oak rainbows should stand for 24 months in the open air for optimal ripening. In order for the necessary physico-chemical changes to take place in the raw wood, it takes time. The ripening of the wood should continue until it reaches the ideal quality that gives the appropriate content of aromatic compounds.

When that level is reached, any longer aging and ripening can cause:
– Excessive degradation of ellagitannins; the wood will give a smaller debt structure
– Loss of certain aromatic precursors (e.g. methyl octalactone isomers)
– Unwanted irreversible mechanical changes – crumbling and splitting, formation of veins – loss of wood
– Increased risk of development of unwanted microorganisms that can produce unwanted aromas on mold or earth.

Experts from Seguin Moreau recommend that oak logs should not mature for more than 48 months.

Barrel formats and barrel thickness

Standard barrels (225L Bordeaux type; or 228L Burgundy type) provide a higher oak-to-wine ratio, more oak flavor, faster extraction and higher oxidation. Large format barrels (400L to 600L) have a lower ratio of oak to wine, give less oak flavor, have slower extraction and allow less oxidation.

Choosing a barrel with a larger volume than the standard ones (225 and 228 L) is practiced when you want to retain fruity notes and enhance the sensation on the tongue. the first thing that is achieved is the reduction of the ratio of wood surface per liter of wine, which reduces the influence of woody notes.

Toasting (AQUAFLEX and ML) recommended by experts Seguin Moreau for larger than standard barrels is a very effective and smart way to add structure to the wine without adding too many aromas (significantly less vanilla, toasted and smoky notes). It has also been shown that wine needs less oxygen during aging. The wines retain more freshness and compactness.

The ratio of the internal volume of the barrel to its internal surface is very important. The geometry of the barrique barrel was not accidentally taken with 225 or 228 L. The ratio of surface area to the volume of wine in the barrel is the best with these dimensions and is calculated as cm² /L or L/cm² of wine and it is inversely proportional to the size of the barrel; in a barrel with a volume greater than 225 L, barricading will proceed more slowly and vice versa.

For these reasons, the barrel of 225 L was taken as the standard and it is in the most common application in the world. What does that mean?
The geometry of such a barrel is such that the ratio of volume to internal surface is approximately or equal to 1 : 100 . This further means that 1L of wine receives 100 cm² or 1L of wine receives 1 dm² of oak surface with which it will be in contact during aging.

This ratio of volume to the internal surface of the barrique barrel was taken into account by the producers of oak alternatives, so if you read my post on aging distillates , you can make your own oak alternatives; just watch the method and degree of toasting!

The most common dimensions of the barrels are:
Length of the bow (height): 94-95cm
Largest diameter (on the side): 69.5cm
Diameter at the ends: 56.5cm
Thickness of the bow: 22-27mm
Thickness of the metal rings: 4 – 6mm
Diameter of the cork opening: 50-51mm
Weight: 46kg

Retrieved from: https://www.kolibica.com

Medium format barrels (265L to 300L) provide features between standard and large. Special format barrels are designed for special needs, such as cigar-shaped barrels that increase the contact surface between the wine and lees.

The thickness of the bar is usually 22mm or 27mm, it can be a factor when it comes to the structural integrity and operation of the winery. If we’re going to be moving barrels around a lot, thicker rainbows might be better; or if we stack the barrels high, we will take thicker long barrels.

A 225-liter barrel has two rails that are 50 mm wide (in the middle of the barrel) and two rails that are 40 mm wide each (at the ends of the barrel).

Domestic oak

Serbian oak can add a much stronger aroma than French oak (Quercus pedunculata and Q. sessiflora). For this reason, in our country, oak is used to make barrels and casks for aging strong alcoholic beverages.

In our country, in the production of wine barrels, Kitnjak oak or Medunac oak is used. There is no more detailed scientific knowledge about the quality of oak timber from our forests. Our winemakers use domestic oak only because it is almost three times cheaper than imported oak.

One should have a good knowledge of the nature of the components that are extracted from wood, knowledge of their reaction with wine ingredients and the correct direction of those reactions and contribute to the improvement of the organoleptic properties of wine.

In this sense, within this post, the most significant knowledge about the nature of the oak tree has been presented; about the changes that occur during the drying and thermal treatment of wood in the process of producing dishes; about the components that are extracted into the wine during contact with the wood; about the characteristics of wine suitable for care in wooden vessels and finally, about the possibility of replacing wooden vessels with alternative materials based on oak, such as granules, shavings, sawdust and other specially prepared preparations and even liquid concentrates of oak.

Many of our winemakers bypass domestic producers of barrique barrels and buy imported second-hand French oak barrels, which are on average about 40% cheaper compared to a new French barrel.

A second-hand barrique barrel must be prepared anew for aging the wine. Depending on how thick the barrel is and the degree of toasting applied to them; deep or shallow toasting; the pinter will have to remove the leached layer of wood from the bow, which can be deeper or shallower and thus reduce the thickness of the bow.

If it is known that the thickness of the barrel is from 22 to 27 mm, it is clear to us that by removing the leached layer as well as by burning again, the barrel will be significantly thinned and mechanically weakened, which makes the barrel itself less resistant to mechanical pressure, and it is not recommended to place such a barrel at a height in the winery.

Long bending and burning (toasting)

There are three main methods of bending the debt that can affect toasting temperature and oak aroma levels. Fire-cured rainbows tend to have a higher toast temperature with more oak structure and more ellagitannins.
Water-cured rainbows will have a lower toast temperature due to evaporative cooling, with more subtle flavors, a more delicate oak structure, and less ellagitannin.
Steam-curled rainbows have a medium toast temperature and give characteristics between those of fire-curled and water-curled.

• Light toasting levels (150 to 177 degrees ⁰C) have a subtle oak aroma, subtle mouthfeel, smooth tannins and will bring out more fresh fruit flavors.
• High or strong toasting levels (190 to 205 degrees ⁰C) provide more intense oak aromas and mouthfeel, firmer tannins and mask more fruit character.
• Medium toasting levels (177 to 190 degrees ⁰C) offer characteristics between light and heavy toasting.

Considerations when choosing a level of toasting include: the style of wine we want to produce, the grape variety, whether there is anything in the wine to remove (green aromas, faults, smoke smell) and personal preferences. When making decisions about this, small trials should be repeated: experiment, try, and so on several times.

Some coopers label barrels and casks with different sub-levels of toasting than those listed above, such as Light +, Medium +, etc. Toasting temperatures and duration can vary significantly between coopers; there are no industry standards.

What do you get from toasting?

The function of the barrique barrel is to enable controlled micro-oxygenation. Oxygen slowly penetrates through the pores of the wood, allowing the natural micro-oxygenation and polymerization of tannins to take place, which make the wine softer and more elegant.

Threshold of sensitivity in mg/l description of some compounds in wine that are formed by toasting debt:

By toasting the inner surface of the wine, new compounds are created that will react with the compounds of the wine during aging.

The wine’s aromatic complex is influenced by the process of production and care, especially care in a new oak barrel, which also has a certain aromatic complex.
For some of the components of the aromatic complex of wine, BOIDRON et al determined the threshold of perception (sensitivity in water, synthetic solution) in one white and one red wine aged in a wooden vessel.

The threshold of sensitivity meant the minimum concentration of a certain ingredient that was noticed by 50% of the tasters.
They also determined the contribution of a certain component to the aroma of the wine based on the aromatic index: I = C/S, where C is the concentration of the substance in the analyzed wine, and S is the sensitivity threshold determined in the synthetic solution.

Toasting the oak for flavor (“bousinage”) affects how much wood aromas the barrel will impart to the wine. Explaining the whole phenomenon, it can be said that the longer the wood is toasted, the wider range of aromas and gentler tannins will be obtained. From experience, we have recognized which method of toasting best suits different oak selections, say Seguin Moreau experts.

Ellagitannins form a “shield” that protects the wine’s sensory profile from external influences:
– They help to open up the aromas by limiting the formation of sulfur compounds during fermentation (especially in white wines) and later during aging.
– They protect against oxidation during aging by binding oxygen to themselves.
The content of ellagitannin in wine is much lower than tannins from grapes, which have the main influence on the taste of wine.

Volatile phenols are aromatic compounds, naturally present in oak, which are preserved during the production process and improve the final notes of wine during aging (eg eugenol which gives the aroma of cloves).

Hemicellulose and lignin are called “wood biopolymers” and they are aromatic precursors in the process of toasting (bousinage), and their transformation under the influence of heat produces a whole range of aromatic compounds: furan – smoky notes and phenol aldehydes – vanilla, caramel and spices.

Methyl – octalactone , its isomers are the basic ingredients for the expression of wood aromas in wine. They are naturally present in wood in varying amounts, mostly depending on the type of oak and the genetics of each individual tree.
Oak also contains precursors of these compounds that can increase the content of lactones during wood aging, toasting and even during the aging process of wine in a barrel.

Oak triterpenoids were recently discovered at the Institute of Wine and Viticulture in Bordeaux and these constituents play a very important role in the sensory profile of barrel-aged wines. They are the ones who give sweetness to those wines that are otherwise dry.

The table shows the comparative content of aromatic ingredients in white and red wine before and after aging in a wooden vessel: (I = C/S)¹

Characteristics of wine suitable for care in a wooden vessel

The care of wine in wooden vessels is characterized by two different but complementary phenomena; on the one hand, wine extracts certain ingredients from wood, and on the other hand, wood is a porous material through which gas exchange occurs, which enables moderate oxidation of the wine.

Not all wines are suitable for care in wooden vessels. Thin wines, poor in polyphenols and polysaccharides, with an inappropriate ratio of tannin and anthocyanin content, when stored in wooden vessels quickly lose color, with a sudden increase in yellow hue, lose fullness, and the taste becomes acrid.

Some data on the content of polyphenolic substances in wine

The amount of total colored and tannic substances in rosé wines is about 1 g/l, and in red wines 2 – 4 g/l. A higher amount of stable colored substances is desirable in red wines, while excessive
amounts of tannic substances can have a negative impact on the organoleptic characteristics of these wines.

In white wines, 0.2 – 0.5 g/l of tannic substances can be found.

The regulations of most wine-producing countries limit the maximum amount of tannic substances in wine to:
0.5 g/l for white wines, 1.5 g/l for rosé and 4 g/l for red wines.
Exceptionally, a higher amount of tannic substances is allowed in red wines, provided that they do not compromise their sensory characteristics.

The maximum amounts of total phenolic substances are generally limited to: 500 mg/l for white, 2,000 mg/l for pink and 5,500 mg/l for red wines.
Due to the simplicity and practicality, the total colored and tannic matter in the wines can be expressed through the so-called potassium permanganate index.

The potassium permanganate index (IMn) implies the number of milliliters of 1M KMnO4 solution required for the oxidation of all phenolic compounds in one liter of wine.

For white wines, the IMn values ​​are 3 – 5, for pink wines 25 – 35, and for red wines up to 70. Red wines obtained from higher-order pressing fractions can have an IMn of over 100.

In pink wines, the content of colored substances is 50 – 100 mg/l, in normally colored red wines 100 – 200 mg/l, and in highly colored wines up to 500 mg/l.

Sudraud proposed the introduction of two indicators of the color quality of red wines, called intensity and hue. Color intensity (J) is the sum of extinctions (E) of the wine at 420 and 520 nm: J = E420 + E520
As red wines age, the numerical value of color intensity decreases.

Optical density at 420 nm gradually increases, but at the same time it decreases somewhat more intensively at 520. Color hue (T) is the ratio of optical densities of wine at 420 and 520 nm: T = E420/E520

The numerical value of color hue decreases more or less quickly with wine aging.

For rosé wines, color intensity values ​​are up to 0.500, and for red wines, very rarely over 1.000. The color hue of red wines generally has numerical values ​​of 0.400 – 0.600.

The values ​​of the intensity and shade of color indicators are of a realistic nature and only gain meaning when compared with the values ​​for the same wine at different times or with values ​​for other wines.

According to GLORIES (1992 and 1993), positive results can be expected if the wines meet the following conditions before being placed in wooden vessels:

1.- the index of total phenolic substances (absorbance at 280 nm) should be 40-45.
2.- the intensity of the color should be relatively high, greater than 0.65
3.- the appropriate ratio between tannins and anthocyanins in order to enable their connection so that one or the other does not degrade.

According to VIVAS (1993), the molar ratio of tannins/anthocyanins should be around 2, which means: (1.5-2 g/l tannins and 0.5 g/l anthocyanins).
4.- the polysaccharide content should be greater than 0.5 g/l. Their presence in sufficient quantity is necessary because they participate in the complexation of tannins, which reduces astringency, and they also contribute to the fullness of the wine.

In case of lack of tannins, there is oxidative degradation of anthocyanins and irreversible loss of color, and if anthocyanins are missing, tannins are partially degraded, yellow components dominate and overall the wine prematurely acquires a brick red color.

For red wines that should mature in wooden vessels, it is also necessary to pick grapes at the stage of phenolic maturity and not at technological maturity. The phase of phenolic maturity occurs in grapes at the beginning of grape ripening.

In overripe grapes, the degradation of phenolic compounds occurs under the action of oxidative grape enzymes and due to photochemical reactions, resulting in wine with an unstable color.

The phenolic ripeness (physiological) of grapes is roughly determined in the field using a pH meter and these values ​​are within:
– for white wine varieties for champagne pH= 2.9-3.1
– for white wine varieties pH= 3.1 to 3.2 depending on the variety
– for red wine varieties pH = 3.3 to 3.4 depending on the variety

Therefore, when we intend to age the wine in barriques, we should analyze the wines and find out whether the parameters of the wine are within the limits shown above. This implies analyzing the following parameters:

1. determination of total colored and tannin substances in wine
2. determination of colored substances (anthocyanins), measurement of the amount of colored substances
3. determination of intensity and shade of wine color
4. determination of total polysaccharides in wine

Barrique barrels provide the wine with the conditions to naturally combine all the factors necessary for stabilization, purification and enrichment of wine both chemically and for satisfying the senses in contact with wood.

Optimal aging conditions

If there is a possibility of air conditioning the space where the barrique barrels are placed, optimization of the barrique conditions is quite possible. Even if there is no possibility of air conditioning, the following conditions should be ensured:

The optimal temperature is  18°C , combined with a relative  air humidity of 85% . If the air humidity is high, the alcohol will evaporate faster than the water, which will reduce its content in the wine.
In conditions of low humidity, the opposite will happen, so the amount of alcohol in the wine will be increased. Regular control and topping up play a leading role here.

The frequency of topping up is extremely important. If it is not done regularly, the upper part of the barrel will dry out, which will cause an increase in porosity and stronger evaporation.

For these reasons, some oenologists recommend that for half of the barrique time the cork hole is kept vertical as usual, and for the other half of the barrique time the barrel is rotated, placing the cork hole to the side.

During one year of aging in a barrique, the percentage of wine evaporation is approximately 4%.

The length of wine aging in these conditions will be determined by the tasting of oenologists and other experienced winemakers. Generally, red wines are aged in barrels for  12 to 18 months . 18 months is the time period for high extract wines, with the parameters mentioned above.

In the production of white barrique wines, this period is shorter, a few months. An oenologist with many years of experience in wine production is in charge of deciding at what point the aging time of the wine in the barrique will be interrupted.

The latest alternatives to barrels and oak

Barricading also brings losses in the wine. It is about the share of “angels”, i.e. quantity, which evaporates through the wall of the barrel. These losses can reach up to 4% on an annual basis.

An elliptical vessel of 225 L has such an internal surface that it provides approximately 100 cm ² for 1 L of wine, so when you take into account that in such a vessel it takes a year to extract ingredients from wood, for a wooden wine vessel of 10 hl, the same extraction effect requires 3.75 years.

The Radoux Barrel Company several decades ago (Stéphane Radoux) worked and still works to preserve the use of oak in the wine industry, only in new ways.

With his new company, Amédée named after his grandfather and known as USA médée in the United States of America, he creates products that will mimic the effect of barrels while addressing sustainability issues in the oak industry.

An average of 10 long barrels of 27 mm thickness and a volume of 225 L can be made from one mature oak tree. However, the primary taste components that we use for wine are found only in the first 8 to 10 mm of wood that comes into contact with the wine, the other 18 mm serves to transfer oxygen and ensure the strength of the barrel.

A 150 to 200-year-old tree has enough wood to produce 10 barrels that could hold a total of 22.5 hL of wine per harvest. Over the barrel’s lifetime of four uses, this translates into a total of 90 hL.

If, however, we could find a way to exploit the flavor components that exist in the 17-19 mm of wood that the wine does not come into contact with, we could produce 63% to 70% more wine (243-297 hL) per tree. Even better, if we could produce 18mm barrels instead of 27mm, we could produce enough barrels to mature 3500hL of wine per tree.

Radoux commented that if all the oak wood was converted into oak tannins, he estimated that number to be as much as 17,500 hL or 194 times more than the tannins available in the wine in 10 barrels made from that 200-year-old tree.

He is not the only person who understood this dilemma. Many have thought about how to respect the contribution of oak compounds to the wine’s character through barrel aging with maximum use of the original material, as well as how the process of using alternative oak products changes the wine’s character.

Large capacity wineries have seriously addressed these losses and their technologists have found a solution to reduce wine losses.
And not only that, using oak alternatives reduces water consumption, reduces manpower, increases the efficiency of the floor area of ​​the winery, reduces the use of chemicals, remediation is easier and it is safer to reduce the contamination of vessels.

With these alternatives, in addition to wine losses, the barrification time is shortened, which reduces production costs. What is new in this is the production of liquid oak alternatives that have been in use in the US for a long time.

Oak slats, cubes, oak chips and powder are also used. Since this shortened the aging time, as well as not having to invest in the purchase of new barrique barrels, wines were launched at lower prices compared to classically barriqued wines.

The introduction of oak alternatives was started and allowed first in the USA, Australia and South Africa. It was found that the processing of such materials is important: heating, degree of burning (temperature height and time).

Mc CORD and colleagues performed experiments heating oak shavings for 4 to 5 hours at 171, 182 and 193 °C , so they concluded that more aromatic components, which positively contribute to the smell and taste of wine, are obtained when the heating is done at lower temperatures.

BERTRAND and BARBE carried out a series of experiments with wines and a model solution to which they added:
– density oak wood extract (density 1.072)
– unburnt and burnt wood chips (previously air-dried for 3 years and then heated to 200 °C without ignition)
– cooked wood
– unburnt and burnt granules (American commercial)
– sawdust (obtained by scraping dried 3-year-old debt)
– two commercial tannin

The extract was added in the amount of 0.3 to 0.9 ml/l (more in red wines);
Chips were added from 10 to 30 gr/l;
Cooked wood, granules and shavings in the amount of 2 to 6 gr/l;
Tannin in the amount of 0.09 to 0.27 gr/l

The mentioned agents were in contact with the wine and the model solution for 4 months at 20 °C . The analysis of certain ingredients of the treated wines and the model of the product showed that vanillin and eugenol are correlated with the aroma, and 4-hydroxyethylbenzoate is correlated with the astringency and bitterness of all experimental samples.

Added tannin and extract did not affect the improvement of wine aroma. Contact with unburned wood and granules had a positive effect on the aroma of the samples.

After the contact of the wine with burnt wood, the amount of aromatic components increased 10 times, but the wine took on the smell of burnt, rubbery, “burnt wine” smell.

The mentioned authors concluded that the best aroma is achieved by contact of wine with 6 gr/l of unburnt wood and 0.75 gr/l of burnt wood in combination.

WYK, according to TROMP, recommended the use of smaller amounts of wood chips, 1 to 2 gr/l for a finer and 3 to 4 gr/l for a more robust smell and taste of wine.

However, like other researchers (McCORD et al., SEFTON and LEE, BERTRAND and BARBE, WILKER and GALLANDER and TROMP), they pointed out that alternative materials cannot achieve such an aroma of wine as when it is stored in new oak vessels.

It is recommended that in the production of white wines, alternative materials are added before fermentation or during the maturation of the wine. Because, when they are added to the wine before bottling, they disrupt their stability due to the deposition of ellagic acid (SEFTON and LEE), which of course does not interfere when the process takes place in a wooden vessel during the maturation of the wine.

WYK (TROMP) also recommends to extract larger amounts of alternative material from oak wood in a small amount of wine, so that such enriched wine is mixed with the original wine in a certain ratio. The mentioned author also recommends the use of reusable wooden dishes, with the addition of some alternative material made of oak wood.

If one of the alternative materials is added to the wine, placed in a cistern or metal tank, it is necessary to ensure the introduction of a certain amount of oxygen and enable the biochemical processes of ellagitannins, gallotannins and anthocyanins to take place.
Wines treated in this way often have an intense smell and taste, but their quality still lags behind that of wines stored in wooden vessels (SEFTON and LEE).

Conclusion

Those less knowledgeable, and unfortunately there are such among wine producers, tend to think that the so-called barrique tone a special quality, which is obtained by keeping wine in wooden vessels, just a passing fad.

The authors are aware of the fact that top quality wines, especially red ones, can hardly be achieved without certain contact between the wine and the oak tree.
The end result of wine care in wooden vessels is influenced by a number of factors; for example: physical and chemical properties of oak wood, preparation and thermal treatment of wood during the production of vessels, vinification and properties of wine intended for care in wooden vessels.

Finally, let me mention the different regions and forests in each country that produces oak vessels.
Here are the world’s best oak vessel manufacturers and brands:

Tonnellerie Quintessence (Bordeaux),
Maison Moussie (Bordeaux),
Tonnellerie Artisanole de Beaune Tremeaux (Burgundy),
Heinrich Cooperage (Barossa Valley, Australia),
TW Boswell (Missouri) and World Cooperage (Missouri).
Cooperages 1912 Barrel

One of the consultants Yuri De Leon said that World Cooperage is the most diversified brand company and produces 3100 different types of oak vessels.
De Leon detailed what characterizes Maison Moussie from France and its innovative toasting technology, the patented heated stone process. It is a non-flammable process and uses natural stones (lava and embers) and water elements combined with heat to create wooden vessels that are evenly fired and durable to create a vessel that enhances fruitiness, finesse and elegance in the finished wine.

Based on the data of modern literature, the authors indicate those factors that contribute the most to the improvement of wine quality.

Bearing in mind that the producer’s financial burden is high when he uses new wooden vessels to care for the wine of one vintage, the authors also pointed to modern trends, in fact to the use of alternative materials produced from oak wood – sawdust, shavings, granules, etc.

In order to gain their own experience, it is recommended that winemakers start trial production of barrique type wines using imported alternative materials, and at the same time develop procedures for the production of domestic oak from our forests and the forests of the region.

Consumer preferences and tastes are changing; people want more freshness in wines and fruity character and less influence of oak. You should keep this in mind when deciding how long to keep your wine in an oak barrel.

What is the legal regulation regarding the declaration of barrique wines on sale, produced using oak barrels and alternatives?

Our Rulebook on quality and other requirements for wine states that the wine producer can put the mark “barrique” on the wine label only if the wine was produced according to the study on the protection of geographical origin.

Small wineries would have to join forces to prepare a joint report on the protection of the geographical origin of their wines, because the preparation of reports is complex and expensive in Serbia.

You will find much more information on this topic in the e-book where I describe the entire process of barrifying wine. The price of the book is $10 and you can download it in pdf format.

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