How, exactly, does aging a beer mellow it out?

Discussion in 'Cellaring / Aging Beer' started by breadwinner, May 21, 2015.

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  1. breadwinner

    breadwinner Initiate (0) Mar 6, 2014 California

    We've all heard, heck even experienced, a beer that has mellowed over time, particularly darker beers like stouts, porters, doppelbocks, quads, etc. One common description of such aged brews is that the booze has really mellowed. But, I assume that the actual alcohol content doesn't change in these beers, right? A 14% bottled barrel-aged stout should still be 14% a few years down the line, no? If so, what exactly is causing this sensation of mellowing? Is is strictly related to the hop presence of a beer fading over time? What else might contribution to this perception?
     
    #1 breadwinner, May 21, 2015
  2. TongoRad

    TongoRad Grand Pooh-Bah (3,884) Jun 3, 2004 New Jersey
    Society Pooh-Bah Trader

    Those fusels (higher alcohols that come across as an acetone-like quality) will break down over time, sometimes even contributing an additional fruity aroma:
    https://byo.com/hops/item/1196-oh-that-smell

    In addition, the beer is usually taking on a pleasant oxidized quality (nutty or sherry-like), and the hops are fading- so you have an overall sensation of coming together and mellowing.
     
    #2 TongoRad, May 21, 2015
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  3. drtth

    drtth Initiate (0) Nov 25, 2007 Pennsylvania
    In Memoriam

    Lots of useful links here that get in to much of the information you seek (including links to such thinks as information about the chemistry, etc.):

    http://www.beeroftomorrow.com/how-to-age-beer/
     
    #3 drtth, May 21, 2015
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  4. breadwinner

    breadwinner Initiate (0) Mar 6, 2014 California

    Good stuff, TR. So, those fusels will break down, helping to "mellow" the beer, even though the actual ABV remains unchanged, correct?

    Didn't think about the oxidization component -- good point.
     
    #4 breadwinner, May 21, 2015
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  5. TongoRad

    TongoRad Grand Pooh-Bah (3,884) Jun 3, 2004 New Jersey
    Society Pooh-Bah Trader

    That's a good question. I suppose if you want to be precise, then there may be some form of small but measurable change, but I really doubt it makes much difference in the end.
     
    #5 TongoRad, May 21, 2015
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  6. BEERschlitz

    BEERschlitz Initiate (0) Oct 13, 2013 Michigan

    I've been told the alcohol actually INCREASES slightly over a long period of time. Something to do with the residual sugars and yeast etc. etc.
     
    #6 BEERschlitz, May 24, 2015
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  7. AugustusRex

    AugustusRex Initiate (0) Apr 12, 2013 Canada (ON)

    Its complicated, I just read Patrick Dawson's "Vintage Beer" and it helped me a lot. There are really a dozen or so factors that each change over time, and also interact with one another. You really have to know your beer and figure it out.

    -Phenols
    -Fusels
    -Esters
    -Beta Acids
    -Hop Oils
    -Alpha Acids
    -Dark/Roasted Malts
    -Microbiota
    -Smoke
    -Oxygen
    -temperature...

    ETC.
     
    #7 AugustusRex, May 25, 2015
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