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  1. #1
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    The Rate of Maturation in the Barrel

    I was just now reading for the seventy-leventh time about the interaction between the bourbon and the inner surface of the barrel. Something about the wording of this particular description caused me to picture that process as it might appear in real time, if only one could peek inside the barrel. ("We all live in a bourbon submarine, a bourbon submarine, a bourbon submarine...")

    I visualized the process moving more slowly than the speed of growing grass, as the bourbon oozes, ever so slowly, into the porous charcoal, then even more slowly (I suppose) into the red layer, and slowest of all into the uncharred oak. As temperature changes occur, they too would propagate slowly because of the thermal mass of the barrel and its contents.

    Then when tiny amounts of bourbon, carrying the flavor components from the barrel, return with equal slowness to the main body of bourbon in the barrel, the mixing process would be incredibly slow. I doubt that there are temperature variations at different points within the barrel that are sufficient to cause internal currents to form. That would mean that only the random movement of molecules causes mixing to occur.

    Then I recalled that some makers move the barrels from one part of the warehouse to another, ostensibly for the purpose of exposing all barrels more or less equally to the external temperature changes. That prompted the following question.

    Is the mixing effect of rolling the barrels a significant factor in the progression of the maturation/aging process? If so, would there be any benefit to rotating the barrels in place from time to time? Do any makers employ this practice?

    BTW, as I write this, I am sipping WT101. (It reminds me that in its own way it's as good as Russell's Reserve, just different.) It's a little early (noon-thirty) for me, but my self-birthday present of Wild Turkey goods arrived today, and I couldn't wait to try out my WT shot glasses. I suppose I'll review them, along with the shirt, cap, and gourmet sauce, in a later post in the Paraphernalia (I'm still trying to learn how to spell that) forum.

    Yours truly,
    Dave "Turkey-Lover, and Proud of It" Morefield

  2. #2
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    Re: The Rate of Maturation in the Barrel

    Based on what I've learned, indeed it seems all of the Master Distillers (those I've talked with or read from) feel that barrel rotation (moving within the warehouse from floor to floor and spot to spot) is a major factor. The bourbon expands and contracts with the seasons.

    Thus, rotating the barrels in place does not seem important since there does not seem to be evidence that gravity effects the bourbon in the barrel.

  3. #3
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    Re: The Rate of Maturation in the Barrel

    I wasn't thinking about the effect of gravity per se.

    I pictured rotating the barrel in place several rotations and at sufficient RPM to create a vortex within the bourbon, possibly causing more rapid mixing of the aged and the relatively un-aged bourbon -- like in a mixing bowl.

    Yours truly,
    Dave Morefield

  4. #4
    Bourbonian of the Year 2003 and Super Moderator
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    Re: The Rate of Maturation in the Barrel

    This is a great thread in that it can be answered by a method of mine that I employ almost constantly, Guesswork! Beam now doesn't move the barrels in the rackhouses, they believe if you mix a barrel from the top with a barrel from the bottom, it should roughly resemble a barrel from the center cut. I would like to emphasis ROUGHLY! So rolling them to achieve mixing isn't done there. This is another reason to like Maker's , at least at present they are still doing it. To Beam's credit since most of their product is the 4 YO white label It probably wouldn't make that much difference. Gary and Mardee Regan state that they do rotate them if "Deemed Nessessary by the Master Distiller" . I will attempt to find out how much if any of that goes on. I believe there is another thing happening in the barrel to mix the contents , however slowly . That would be a " Wicking Effect". I think that as Bourbon evaporates and a void at the top of the barrel gets larger, that bourbon is carried through the charcoal and the caramelized layer and in the oak behind it , around the entire circumferance of the barrel . If it did not then the top of the barrels would dry out and sping a leak. It would be great if someone with access could drill a small hole in a barrell that had been undistubed for years and determine the actual moisture content at the top of the barrel. That being said this whole process is a slow one and it probably sees the most mixing in fall and spring. Theoretically right now the wood behind the caramelize layer is being infused with the bourbon as the 90+ temperatures cause it to expand into the wood. The coldest days of winter will have it all contracted to the void inside of the barrel. You would think that sometime after 1934 someone somewhere would have found out what all the rates of expansion and contraction are for a barrel of whiskey.

  5. #5
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    Re: The Rate of Maturation in the Barrel

    Dave wrote "I pictured rotating the barrel in place several rotations and at sufficient RPM to create a vortex within the bourbon, possibly causing more rapid mixing of the aged and the relatively un-aged bourbon -- like in a mixing bowl."

    Dave all of the whiskey in a barrel was entered on the same day. It's all the same age. There can be no "aged and relatively unaged bourbon" in the same barrel unless some new raw whiskey was added at a later date. As Greg said seasonal changes do all the work. Manual manipulation of the barrel in place is unnecessary.

  6. #6
    **DONOTDELETE**
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    Re: The Rate of Maturation in the Barrel

    Bobby Cox wrote "You would think that sometime after 1934 someone somewhere would have found out what all the rates of expansion and contraction are for a barrel of whiskey."

    Distillers have been at this a long time and I am sure that the rate of maturation and the effects of aging and the evaporation rates of water and alcohol from the barrels are known as precisely as possible given barrel-to-barrel and rackhouse-to-rackhouse differences by both the master distillers and their quality control staff. I'll bet this kind of information was collected in the late 1800's no matter how informally the data were collected. Just long term personal experiance on the job of simple practical distiller's would give them an intuitive knowledge of the aging process. When you have very long term family distilling experience spanning many generations that kind of knowledge adds up. It never hurts to ask these kinds of things whenever your arround a master distiller. Whether or not they will tell you what you want to know is another thing altogether. Beam me up Jim!

  7. #7
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    Re: The Rate of Maturation in the Barrel

    I understand that the bourbon in a single barrel is all the same chronological age, but that does not necessarily mean that every drop within the barrel has had equal contact with the char/wood, and without that contact it seems to me that it is not "aged" in the same sense as a drop that has entered and exited the char/wood.

    I could understand what you are saying if the entire volume of bourbon in the barrel were absorbed into the char/wood and then expelled back into the hollow of the barrel during one temperature cycle. Obviously, that is not the case.

    May we consider what might happen after a barrel is freshly filled with white dog? I assume that at most two or three gallons are absorbed as the temperature rises, leaving 50+ gallons of white dog to lie motionless in the hollow portion of the barrel. Only a tiny portion of that 50+ gallons is in contact with the inner surface of the barrel.

    I further assume that of the amount absorbed some fraction (one-tenth? one-half?) is expelled back into the white dog (the bourbon that hasn't been absorbed into the wood yet) as the temperature drops. That expulsion might happen so gradually that the matured bourbon forms a layer, lying close to the interior surface of the barrel like ground fog, while white dog remains motionless, undisturbed, and unmixed with matured bourbon, throughout the remainder of the barrel.

    In that scenario, during the next cycle the same bourbon, still lying close to the surface of the barrel, would be absorbed and expelled once again, and so on for every year to come. The vast majority of the bourbon in the barrel would never interact with the char/wood at all. Any mixing would occur only as or after the bourbon was eventually dumped.

    If that's not what happens (and I'm betting that it isn't), then what does? Does a so-called "seasonal change" cause the bourbon to squirt out of the wood so fast that it swirls the entire contents of the barrel causing mixing to occur? Doubtful.

    Does the random (aka, "Brownian") movement of molecules throughout the barrel upset my theory about the formation of a layer of matured bourbon? Do these sub-microscopic movements suffice to mix the recently expelled, matured bourbon with the part that hasn't been inside the wood yet? (One of my original questions, IIRC.)

    Is matter from the interior surface of the barrel being slowly dissolved into the main body of liquid (and presumably being dispersed by Brownian movement), adding to the effect of the pumping action caused by seasonal changes?

    Is there some other factor that I haven't thought of that mixes the relatively small amount of bourbon that enters and then leaves the wood with the much larger portion of bourbon that does not enter the wood during one temperature cycle?

    Is there a chemical engineer or a fluid mechanics specialist in the house? I need a drink.

    Yours truly,
    Dave Morefield

  8. #8
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    Re: The Rate of Maturation in the Barrel

    Linn Wrote "Beam me up Jim! "

    It made me think of Deforrest Kelly and how he would berate Capt. Kirk," Damnit Jim, I'm a doctor, not a bricklayer!" Then he would bitch about Jim sending a bunch of guys to the surface of a planet and getting them blown to bits and how he would have to put them all back together. And all he had to do was point a box at them and completely regenerate any thing needed. " What?" You may ask, does this have to do with the rate of maturation in the barrel , well not much really! Actually that one line delivered by" Bones" just seems to sum up Star Trek for me . It has all sorts of uses and I can imagine entire conversations using variations of that one line." Damnit Linn ,I'm a senior member, not a moderator!" or" Damnit Booker , I'm a barrel roller, not a master distiller!"

  9. #9
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    Re: The Rate of Maturation in the Barrel

    >Does the random (aka, "Brownian") movement of molecules throughout the barrel
    >upset my theory about the formation of a layer of matured bourbon? Do these
    >sub-microscopic movements suffice to mix the recently expelled, matured
    >bourbon with the part that hasn't been inside the wood yet?

    Okay, let's run a back of the envelope calculation to find out.
    A typical diffusion constant in a liquid is 10^-5 cm^2 / sec,
    so taking the standard estimation for distance travelled, x = Sqrt( Dt ),
    we get x = Sqrt (10^5 * 60 * 60 *24) = 0.93 cm / day,
    or in other words, everything in the liquid is probably a centimeter
    away from where it was yesterday.

    That might not seem like much, but remember, a molecule is only
    about 10^-6 cm in size, so it's gone a distance that's a million times
    its size.

    So to answer your question, Brownian motion provides a certain
    amount of "automatic self mixing" that keeps things stirred up...
    but we all know that stirred things dissolve much faster than
    things that aren't stirred, so your original theory is correct: to
    a certain extent, a barrel that's stirred regularly will age faster.
    As a matter of fact, people in countries where men wear skirts
    have been known to put barrels of distilled spirits on sailing
    ships so that the sloshing of the waves would help things
    along.

    It turns out that aging is much more complex than just dissolving
    the barrel... oxygen slowly diffuses into the barrel to oxidise
    things a bit, acetic acid slowly reacts with ethanol to form
    ethyl acetate, etc.

    >Does a so-called "seasonal change" cause the bourbon to squirt out of the
    >wood so fast that it swirls the entire contents of the barrel causing mixing to
    >occur?

    In my opinion, much more important than seasonal changes are daily
    changes! How many times have you been sweating at noon, but
    cold at midnight?


    And finally, in regard to moving barrels around in the warehouse so that
    they all taste the same: it certainly makes the blending a much easier job!
    I say it's a cop out! Where's the art in blending together things that all
    taste the same? ( Yes, I realize that every barrel at MM doesn't taste
    exatly like every other barrel. )

    Tim

  10. #10
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    Bourbon Submarine!

    I love the phrase and the visual it gives. If only we could see inside the barrel like that.

 

 

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