The rum that comes out of the still or the distillation column can follow different paths. White rum can be bottled as is or almost, aged for a few months, a few years, or for a very long time. In this article, we invite you to discover the secrets of old rums.
The ages of rums
White rum is most often reduced to a suitable alcohol content, with water that must be as pure as possible. To erase the aggressiveness of raw rum without affecting its intensity, this reduction is done as slowly as possible. The objective is to integrate this dilution water as best as possible so as not to obtain a watery character. Time itself also plays a role in the aeration and harmony of the rum , which is why some distilleries spend from a few weeks to sometimes several years the duration during which the rum will be rested, stirred and aerated. This is particularly the case for rums offered as " brut de colonne ", such as Longueteau's Genesis , which benefits from a resting time of 24 months.
Some rums are placed for a few months (at least 12 and maximum 36) in oak casks to obtain what are called wood-aged, amber, gold or straw rums. The casks are large oak vats that can hold up to several tens of thousands of liters. The rum benefits from a rest there which allows it to soften, to tint it slightly and to bring it some woody notes. The quantity of rum in contact with the wood is quite low, given the volume of liquid, so we are not really talking about aging but rather about rest.
It should be noted that some rums aged in wood can be aged in barrels. This is the case of Neisson's Profil 105 which gives a result of striking maturity.
There is also a “brown rum” category as defined in the French Antilles IG, which covers rums aged for 6 to 12 months.
Old rums
Old rums can be called this from 3 years of aging. Beyond that, they can take other names like VSOP (Very Superior Old Pale) which corresponds to aging of 4-5 years , then XO, very old or out of age beyond 6 years .
These prolonged aging processes enhance the rums by giving them aromas from the barrel, but also and above all by allowing them to develop their own aromas thanks to a multitude of chemical reactions. The life of the rum in the barrel gives it color , the contact with oxygen causes an oxidation which modifies its character. The interaction between the alcohol and the fatty acids of the wood also produces an important phenomenon called esterification , which develops aromas (aromatic congeners) additional to those already created during fermentation.
The barrel
The choice of barrel used for aging is essential because it greatly influences the aromatic profile of the final product. The most widely used type of wood is oak , and in particular the ex- bourbon barrel made of American white oak . The explanation is simple: to be called bourbon, an American whiskey must have been aged in new oak barrels. Imagine the millions of barrels that have only been used once and that end up on the secondary market, particularly the rum market. The ex-bourbon barrel is therefore extremely common, even if new American oak, French oak from Limousin and ex-Cognac barrels are also quite widespread.
The different types of barrels can have different capacities but also and above all different characteristics. For example, the standard size of the American oak barrel is 200L while that of the Cognac barrel is rather 300L and that of the sherry barrel 500L. The ratio between the quantity of liquid and the surface of contact with the wood is already an important variable. Note also that the thickness of the staves ("boards" which make up the barrel) is also variable, which will change the relationship of the rum with the wood but also with the air.
The grain of the wood is also important, as is the heating that has been applied to it. American oak has a rather coarse, uneven and tight grain. It contains a lot of vanillin and lactone (we will come back to these chemical aspects later). Limousin oak also has a coarse and irregular grain, it is very hard but its pores are very large. It also has the particularity of diffusing very quickly in the liquid and of containing a lot of tannins .
The making of the barrel
To make a barrel, we generally prefer trees with very straight trunks that have grown slowly and therefore offer very tight rings for a slow diffusion of aromas. We also look for species with a good balance between tannins and aromatic or textural elements.
The cooper cuts the trees into staves which he then seasons , that is to say he dries them but also subjects them to wind, rain (which rinses away excess tannins for the first time), heat, UV rays, air, insects, etc. In the United States , this process lasts from 18 to 36 months, sometimes more, while in Europe it lasts at least 36 months. It must not be too long in order to keep some life in the wood, to preserve the aromas and to limit the risk of breakage during assembly. In addition, we try to carry out the operation as close as possible to the original environment.
Preparing the barrel
When the barrel is assembled, it can be used new to extract a maximum of woody properties. But often the barrel is heated (toasted) or burned from the inside before being assembled completely. This burning promotes wood/liquid exchanges, develops (or inhibits) certain aromas and provides an activated carbon which allows certain substances to be filtered, such as sulfur for example. It is also partly responsible for the more or less dark color of the rum.
A light burn (as for Mount Gay rums) develops rather spicy notes (for example by releasing the vanillin contained in the oak), wood or even earth. If we burn the wood a little harder, we see more notes of nuts appear (as in Neisson rums). And then if we completely carbonize the surface of the barrel, we have a lot of color and notes of caramel , smoke, roasting (typical of Dictador rums).
The preparation of the barrel has an influence on the molecules contained in the wood, and therefore on what is found in the rum. Here are some important chemical elements which, when they are "exploded", release their aromatic substances (congeners):
– Hemicellulose : this form of glucose is a polymer. It is found in rum in the form of sugars such as fructose which provide roundness . It also contains other sugars which separate when stimulated, by heat for example. From 140°C, it gives color by what is called the Maillard reaction, which could be summarized by caramelization . This is how a light or medium burning of the barrel brings aromas of nuts, butter, maple syrup, while the carbonization of the wood brings aromas of caramel.
– Lignin : This is the polymer that gives wood its rigidity. The aromatic congeners released by lignin when burning the barrel are: rather sweet and spicy (vanillin) with light heating, and smoky with strong toasting.
– Tannins : they diffuse naturally into the liquid without the need for heat. This is a natural protection of the wood which is characterized by a strong bitterness . Sufficiently evacuated during seasoning, they help with a light and welcome oxidation, and can give an aroma of cooked apple for example. In the long term, they provide a substance which allows the rum to maintain a dynamic profile despite prolonged aging.
– Lactones : Mainly present in white oak (and in even greater quantities in Asian oak, which is very little used), these are neither polymers nor sugars. They are aromatic agents that come from lipids. They provide notes of coconut, wood, and plant, developed by light burning and inhibited by carbonization.
The barreling
Most of the time, freshly distilled rum is reduced before being put into barrels. Too high an alcohol content attacks the wood and extracts a lot of tannins. The barreling is therefore done at around 60-80% alcohol. A high content extracts more vanillin, while a lower content gives more sweetness and roundness.
Rum loses more or less alcohol during its aging. If the barrel is placed in a humid atmosphere , saturated with water, the alcohol tends to evaporate in greater quantities than the water. Conversely, in a dry cellar , the water is "pumped" out by the air and it is even possible that the alcohol level is higher at the exit of the barrel than at its entry, the water / alcohol proportions having been modified.
This evaporation called " Angels' Share " is very important in tropical climates where it reaches 8% per year, while it is more limited in Europe with an average of 2% per year. The more a barrel is partly empty and dry, the more liquid it drinks, hence the practice of topping up which consists of replenishing the level of the barrels with rums of the same age in order to limit evaporation.
Rum also extracts different aromas from the barrel depending on its alcohol content: each substance in the wood is soluble at different levels of alcohol. This is why, in general, the older a rum is, the more complex it is, because it has had access to all the substances that the barrel could give it, as the alcohol content has dropped. Thus, the tannins degrade first, then the lignins, then the hemicelluloses.
The complexity of aging
The aromas provided by the wood and the chemical reactions which take place during aging therefore depend on the type of wood, its seasoning, its heating, its environment, but aging obeys even more complex laws.
The barrel may be new, but it may also have been used many times. Some old barrels therefore no longer have much to give and are therefore primarily used as storage rooms. Other barrels may also have been used to age other alcohols such as sherry, port , wine, etc. In this case, the wood restores the characteristics of the previous alcohol still contained in the staves, in addition to its own characteristics.
We can also use other species than oak: acacia or chestnut, or dozens of other exotic species such as for Cachaça (Umburana, Jequitiba, etc.), the spirit made from pure sugar cane juice from Brazil.
These different types of wood or barrels can be used for a complete maturation , but we can also mix the influences of these woods by carrying out double maturations (like this Plantation Barbados 5 years old aged in a barrel that contained bourbon and ex-Cognac barrel). These double maturations can also be done partly in tropical aging, and partly in “continental” aging. The practice of finishing consists of refining the rum for a few months in a fairly marked barrel to bring an additional touch (like for this Plantation Pineapple in a peated whisky barrel).
Many other practices, more or less admitted, can be used to act on the rum during or after its aging: addition of woody substances (liquid wood concentrates), sugar, molasses, wines, etc.
Finally, some distilleries and brands add spices, fruits or herbs during aging to make spiced rums, more commonly called spiced rums .
The assembly
Each rum barrel is different within the aging place ( the cellar ). The mastery of aging by the cellar master allows him to have different barrels, more or less marked by the wood, more or less old, with varied origins and species. The place in the cellar is also important: the barrel reacts differently depending on whether it is high up, under the roof, in a draft, sheltered, etc. The cellar master uses these barrels as one develops a perfume and seeks to create, and what is the most difficult, to reproduce a blend indefinitely. Examples of rum blends are for example VO (Very Old – 3 years minimum), VSOP (Very Superior Old Pale – 4 years minimum) or XO (extra old – 6 years minimum).
The blend thus produced rests for some time in a vat or cask so that the different rums can blend and harmonize. Remember that the age that appears in the end on the label is that of the youngest rum. Thus, if a vintage is the result of the blend of rums aged 15, 18 and 21, it is designated as a 15-year-old rum.
The cellar master sometimes comes across an exceptional cask and chooses to offer a single cask bottling, without blending.
Bottling
After the rum has aged, the final stage of bottling comes. When it comes out of the barrel, the rum is most often reduced to an acceptable alcohol content. We have seen that it has often already been reduced when it was put into the barrel, but it may also have been reduced slowly during the aging process in order to soften it as gently as possible.
Some rums are bottled " brut de fût ", that is to say without reduction after aging (which does not exclude a reduction during aging, as for JM vintages). We can also find the equivalent term "cask strength" or "barrel proof". The term "full proof" corresponds to an absence of reduction since distillation.
The color of a rum can be adjusted with caramel , because as we have seen, each barrel is unique and it is impossible to maintain the color of a blend over large quantities.
Some rums are deliberately very colorful, they are part of the dark rum family.
The last step before bottling is filtration . It can be light and mechanical, or it can be cold or charcoal filtration, which makes the rum very clear and removes any wood particles, but which removes some of its aromas.
Very nice article, all the stages of rum are simply and clearly explained.
Well done and thank you.
Thank you Jacques, very happy that you enjoyed reading it.
Nico
Great read…does a barrel that has been toasted rather than charred make the rum darker?
Thanks for your comment Russell. Charring is basically “heavy toasting” so it will impart more color to the rum, as well as darker aromatic notes (coffee, burnt caramel, smoke…)
Great articles, well documented!
Thank you David! Nico and I are glad that you enjoyed reading it.
Good morning,
First of all, thank you for this pleasant article to read which must have required research and time.
If I may give some details for the readers of your blog.
By the way, VSOP means 'very superior old pale' and not very 'special' old pale. A term that came about in the 19th century to differentiate the quality of real barrel aging from colored and artificial aging that was beginning to invade the market.
Congeners come from fermentation and are present in the brandy, not in the wood. But yes, some will evolve during aging. Congeners or TNA, non-alcohol rates were named thus at the 5th chemistry congress. Before that, they were called impurities.
•As regards leaching when exposing the staves outdoors for drying, the following applies:
Tests carried out on a stack of staves arranged in a square stack of 170kg. Extract from the Cooperage Manual by Nicolas Vivas, oenologist, doctor of science, research & development director of a large French cooperage.
"The elimination of a part of the water-soluble substances from the wood takes place, for the most part, during the first 6 months of the six drying, when the wood is still green and rich in August. Then during the drying, the progressive decrease in the relative humidity rate and the tightening of the wood fibers trap the extractables in the mass. Even heavy rains, occurring after 8 to 10 months of drying, contain little or no extractables. Report the annual loss of dry extracts to 170 kg of wood and 6.14 mg per kilo of wood, which is low... This result indicates that only 0.035% of the extractables from the wood have been carried away by leaching... it appears during tasting that this extract is more bitter than the oak extract not carried away by leaching."
During the natural drying process, there are:
-elimination of water–> reduction of wood humidity (60% to 15%).
- Elimination of fatty acids––> reduction of sap aromas.
– leaching of water-soluble extractives and oxidation, hydrolysis of ellagitannins––> reduction in astringency.
– Development of micro-organisms––> reduction of bitterness.
– Transformation of Whisky Lactone precursors and other aromatic compounds.
–
•For oak, regarding this subject, wood is composed of non-extractable substances (Lignin, Cellulose, Hemicellulose) and extractable substances (phenolic compounds - tannins, phenol, .. - fatty acids and other aromatic substances such as lactone).
-It is the different heatings and the high alcohol content of spirits that are capable of degrading the polymers (non-extractables mentioned) of the wood with the formation of alcoholysis of lignin and alcoholysis of hemicelluloses. As you say in a comprehensive manner, the degradation of lignin gives vanillin which is a compound that results in vanilla aromas.
•In wood extractables, each compound has sensory characteristics.
Here are some of them:
Furfural gives aromas of caramel, toasted bread.
Guaiacol is the smoked one.
Vanillin (a compound) gives the vanilla aroma.
Eugenol, spicy aromas
Ellagitannins, astringency.
Nonenal, sawdust and green wood.
Non-volatile compounds resulting from the degradation of lignins and hemicelluloses, sweetness and body.
•For heating, a light heating will bring more floral and fruity notes and will be more marked by the origin of the brandy, while a strong heating will bring vanilla and woody aromas marked by aging.
Obviously, we can go much further.
Those who are interested can refer to the works of Arroyo or Puech. Or obtain reference works such as:
-“the book of cooperage” by J.Taransaud.
-“Cooperage manual for barrel users. N.Vivas.
I also confirm that the term Cask Strength = barrel strength (USA) = brut de fût is indeed without the addition of water during aging by any process whatsoever and also without filtering. Otherwise Brut no longer means Brut?.
Thank you.
Many thanks for this considerable contribution Jean-Marie.
Regarding esterification in the barrel, I did indeed complete my sentence and specify that these were additional congeners to those already created during fermentation. It was not very clear, thank you for your remark.
This phenomenon is also crucial because a technically rather light rum can end up in another category after a few years of aging. I think back to this anecdote told by Matt Pietrek (Cocktail Wonk) about a Long Pond rum whose “mark” indicated a TNA in the range of 90-120 g/hlap, and which ended up at 277g/hlap 18 years later. As a result, one could ask the question as to the relevance of keeping this famous mark at the exit of the cask. But it turns out that beyond a TNA, a mark also relates to a certain profile, so it would be even less relevant to adjust this mark at the exit of the cask.
Regarding cask strength, the reduction during aging does not bother me a priori. Without any operation carried out at the outlet of the cask, we could literally consider that it is cask strength.
However, we cannot act as if the term does not exist elsewhere and the question of legitimacy does indeed arise. We should not discredit ourselves by “mimicking” practices and reclaiming terms for purely marketing purposes. As you say, it is probably not a question of deception, but rum risks being discredited as a “serious” category.
This problem is added to all those linked to the fact that rum is a global product (sweetening, age statements, and even raw material in certain cases...), which is the biggest challenge to overcome for a common global definition of rum.
Good morning,
Thanks for this great article!
Question may be stupid, when bottling, is the barrel mixed? The liquid in the barrel is not homogeneous directly if? The parts of the wood do not give the same flavors at each place in the barrel the bottles from the same barrel will not have the same flavors
Thank you in advance for this clarification.
Hello Valentin, thank you for this comment.
Most of the time, rums are blends of several barrels, which are “transferred” into vats to mix, harmonize and stabilize. During this operation, one can also use cold filtration or a simple mechanical filtration which rids the rum of “barrel dust”.
For single barrels, the rum is naturally mixed during its unloading before reaching the bottling line.
I hope I have answered your questions, thank you!
The rum is therefore not mixed during its aging time in the barrel. Only at the end during filtration, it is "transferred" into another container (the mixture is done at this time) before bottling.
Thanks for these answers!
Interesting question asked by a reader “Does the level of humidity outside affect the quality or taste of rum?”
Answer: Yes, humidity plays a major role in the exchanges between the liquid and the barrel. For example, if the ambient air is humid, the barrel will be humid and there will be more evaporation of alcohol than water. Conversely, in a dry cellar, the barrel will tend to draw more humidity from the rum. The concentration of the rum will then be really different depending on the humidity conditions in the cellar.
Good morning
Great article!
Is it possible to age your rum yourself in small barrels (2-3 or 5L)?
If so, what advice would you give on choosing the barrel?
Choice of gasoline?
To Toast or Not?
New barrel or one that has already contained another alcohol?
Sincerely
Hello Kevin,
Thanks for this comment and for this question!
Of course, it is possible to try the experience of home aging, it is even quite fun!
For the size of the barrel, I think it is interesting from 5 liters, or even 10, if you want to age your rum a little longer. In a small container of 2 or 3 L, the wood / liquid ratio will be so important that the rum will only be able to stay there for a few weeks, otherwise it will be completely absorbed by the wood or suffer too much influence from it.
To choose your barrel, I would say to do according to the opportunities you have: American oak and French oak have proven themselves, but you may be able to find other species and have your own experience.
As for toasting, either you buy the barrel from a professional who will offer you several heating levels (in this case, you might as well take a gentle or intermediate heating for a first try), or you recover or buy a ready-made barrel, and you will not have a choice, or not necessarily traceability. In any case, in the context of amateur aging, I think that subtleties such as heating are not priorities.
For a beginner, the priority will often be waterproofing! I advise you to bathe your barrel upon receipt (unless you are certain that it has been freshly emptied, if it is second-hand). This will rehydrate and re-expand the potentially dry and shrunken staves.
Then do a test filling with water to check the tightness of the barrel body, and especially the tap. If your barrel is new, leave the water for a few weeks to drain as much of the first tannins as possible, which are very aggressive for your rum.
You can begin a first aging in new barrels, but only for a few weeks, or even a few days. The alcohol will begin a much greater extraction of tannins than water and the rum will be extremely woody, extremely quickly. You will have to taste every day during this first phase.
To avoid “losing” a first batch of rum, you can prepare the barrel with another alcohol that you are willing to “sacrifice”. For example, you can use a wine, a fortified wine (Port), another spirit… to your taste! In this case, you can leave this alcohol for a few months during which it will prepare the wood by extracting a lot of tannins and injecting some aromas.
You can then start aging the rum, while continuing to monitor it closely (taste regularly, because it is difficult to recover a rum that is too woody!). Depending on the size of the barrel, the storage conditions (humidity, etc.), the strength of the rum, the aging will happen differently. Note that you will rarely go beyond 3 years, and that in this case you will have to leave about 2/3 of the liquid to the angels!
The smaller the barrel, the more evaporation you will have. You can possibly complete the evaporation level with white rum (because the fuller the barrel, the less evaporation there will be), but your old rum will be less concentrated, less “aged”.
That's it for these few avenues to explore, know that the times and methods that I have given you are only examples, and that your aging will be unique for a whole bunch of reasons and parameters that I will let you discover!
You will see that we then understand why cellar masters are artists as well as great technicians and engineers!
Let us know if you get started! 😉
Thanks for all the advice.
I'll try to find a barrel or two and give it a try.
I will keep you informed afterwards.
Well done Nicolas
For this beautiful, well-documented article for which Jean-Marie provided details. Just a little additional clarification: the ESB, amber, straw category, the minimum is 12 months and not 18. There is also the “brown” category as defined in the French Antilles IG, which is from 6 months to 12 months.
Thank you very much Jerry for these details. I just discovered the existence of this “brown” category in the last episode of the single cast 😉
However, it is indeed widely used in the world of GD rums!
Informative article, which allowed me to remind myself of certain fundamentals
Congratulations for this article which made me discover “Le Rhum”.
Henry
Good morning,
I age my own aged rum.
Let me explain, in 1 litre bottles with screw caps, I put a 20 cm quarter round of oak, heavily charred with a blowtorch on 3 sides, with 1/3 of a vanilla pod split in the middle.
I reduce my white rum to 45° with the least mineral water possible, because it is 59° or 60° when I bring it back in cubis, I then bottle it at a volume of about 90 centilitres per unit, I do not fill them completely to allow a little air to act during aging.
I then store the bottles for at least 3 years under my roof in the heat of the summer to imitate tropical conditions, taking care to open them for a few minutes 3 times a year to renew the air and imitate aging in barrels.
The advantages of this technique are:
1/ new wood gives incomparable aromas to the rum, unlike the majority of distilleries which for economic reasons use barrels that have been completely washed out for decades and have nothing more to add to the rum, so much so that without saying so they often add caramel coloring E 150 authorized by law, to imitate the bousinage.
2/ With screw caps, you regularly aerate the rum without having the “angels’ share”
Do not hesitate to steep it continuously to obtain notes of nuts as well as a satisfactory colour, in this case six to eight months after bottling your rum will already have its final colour.
After three to four years under your roof you can store it in the cellar.
Well done, great article!
Quick question: I heard (hence my need to check) that the age of a rum varies depending on the country... In Guadeloupe, 3 years would be equivalent to 9 years... True or False?
THANKS
Thanks Clément for this feedback! The age does not vary by country, but the evaporation and the speed of extraction and concentration of wood compounds do. The angels' share in Europe is on average 2-3%, while it is 8-10% in the tropics. We would then tend to say that rum ages 3 times faster in the tropics, which would perhaps be a bit simplistic, even if it does indeed acquire a certain maturity there more quickly. In any case, this does not mean that rum is literally older. So I would say False, but….. 😉
Great! Thank you very much for this answer.
Good morning !
I would like to know if you can age rum in an olive wood barrel? I brought back from Crete a 5.5 liter olive wood barrel, having been initially seduced by the beauty of the object. I have just put water in it and then I would like to first put an alcohol in it whose aromas will then perfume the white rum that I plan to put in it. I live in Guyana and we have a white rum that I find excellent, the “Belle Cabresse”. Thank you for your comments and suggestions.
Hello Georges,
We don't have an example of rum aged in Olivier barrels, you have to try it, taking care to taste it often.
La belle cabresse is an excellent rum to age in small barrels.
Please feel free to give us feedback on how it went!