Phenols in train-ing?

I recently received a fascinating email that occasioned my learning a few new and interesting things about phenols.

To excerpt from the intial email:

“…(the taster) commented on the consistent style of the wines as having big but very soft tannins. I told him (as I have told so many others but kind of tongue in cheek) that the softness of the tannins was a result “train settling, ” Because our barrel room is located under a railroad overpass, the barrels are gently vibrated with each pasing train and that this gentle vibration helps create longer phenolic chains. The wines are gently “shaken not stirred” 21,000 times/year (that’s how many trains pass overhead each year. [The taster]was quite intrigued by this explanation and suggested that I should see if, in fact, there might be something to that theory. And so… I am asking you, do you think there could be any merit in thinking that the gentle vibration of our barrels some 21,000 times/year could contribute to the softness of the tannins in our wine?”

And from my response:

“…Though I really don’t know much about tannin chemistry, curiously enough, I work and am friends with two experienced grad students who research that very topic. One of these gentlemen has made wine in Argentina for ten or so years, consistently with an interest in polyphenol chemistry, and can probably rightly be considered an expert on the topic. I consulted them on your question and will do my best to summarize what they had to say. Please keep in mind that this is a very complicated question dealing with a very complicated and not fully understood topic on which active research is underway.
First, your assumption that longer phenol chains (i.e. a higher degree of phenol polymerization) are directly associated with “softer” or less-astringent tannins is not true. You are certainly not the only one to anecdotally think that longer tannins are softer tannins, but several published studies conducted over the last ten years have disproven the theory. Longer chains, appear to be more astringent, if slightly less bitter than shorter ones, with the relationship being non-linear and of relatively small magnitude. Stephane Vidal at the INRA Montpellier (an eminent French agricultural and sensory research institution) has done much of this work, along with Ann Noble’s group at UC Davis.
Second, there is no reason to think that vibrations will increase the degree of polymerization of your wine’s phenols. Sorry! To the best of our (my friends’ and my) collective knowledge, there is no data bearing on this question. From simple chemistry and common sense, however, vibration should increase polymerization only if addition of mechanical energy was important in increasing the number of collisions between phenol molecules. Since phenols are already in high concentration in wine, this may not be the case. Moreover, as already mentioned, the “old winemakers’ wisdom” that increased association between phenols and of phenols and acetaldehyde is responsible for the softening of red wines with age has been debunked by combining chemical and sensory analysis.
I’ll admit that the first reaction of my friends to your train-vibration hypothesis was “typical winemaker B-S, looking for a way to distinguish his wines.” Depending on your point of view, I tend to be either a bit more gullible or a bit more creative. Regardless, a bit of musing led us to think of one potential way of relating astringency to your locamotive proximity. As I’m sure you know, yeast lees can have a softening effect on wine. Yeast autolysis, a particular kind of cell death, causes release of polysaccharides and, in particular, mannoproteins into the surrounding wine. Stirring up the lees encourages cell-wall breakdown and the release of these compounds. Yeast-derived polysaccharides associate with phenols (the particulars depend very specifically on the types of polysaccharides involved, but this is a fair generalization) and stabilize the folded molecules, hindering denaturation and the exposure of hydrophobic regions that aggregate to form large and insoluble polymers. Thus, yeast autolysis reduces phenol precipitation. Since the perception of astringency occurs when tannins precipitate, yeast autolysis generally reduces astringency. Returning to your train vibrations, it is possible that the vibrations gently but frequently agitate the lees in your barrels, stirring up dead yeast components, and keeping more of your phenols in solution. This is purely hypothetical, but it’s a thought.
Finally, and perhaps needless to say, all of this depends a great deal on the varieties with which you are concerned, your particular vinification practices, and exactly what Paul (and you, and other tasters) mean by “big but soft tannins.” I can see from the Barrister website that you deal with a lot of varieties and your email implies that Paul saw this softness of tannins throughout the reds which, naturally, suggests association with your winemaking techniques and style. With respect to the yeast-stirring hypothesis, how often you rack and the strain of yeast you use and such will be relevant. “

Now, if I could only induce this winemaking gent — or another with access to a busy bit of railway — to store identical batches of wine under “trained” and “untrained” conditions and perform liquid chromatography analyses for phenols and sensory comparisons between the two conditions. Not precisely a widely-applicable study, but unquestionably interesting. And who knows? If the good-vibrations wines performed significantly better than their restive counterparts, there might be a market niche for gently vibrating wine aging platforms!


3 thoughts on “Phenols in train-ing?

  1. This is very complicated compared to the simple pleasure of enjoying a glass of wine but I guess it is a necessary question for winemakers.

    Nevertheless, their are several other viticultural & oenological techniques that have already been discovered to manage tannins. Winemakers are already manipulating and crafting wines that have tannin structures that suit them and their target customers. Perhaps vibration would be more natural?

    Why do they say that the ideal storage conditions for slowly improving certain bottles of wine include steady temperature, fairly high humidity, absence of light and absence of vibration? Would polymerization of tannin only occur in barrels?

    I have some of my bottles stored in a Wine Fridge which controls the temperature, light & humidity. It has rubber bushings on the feet but everything still micro-vibrates whenever one of these unit’s compressorors kicks in. Is my “Eurocave” bad for long term bottle storage or beneficial?

    The question of railway vibration reminds me of the debate about the efficacy of those magnetic coasters that are maketed to improve a bottle before opening. – by aligning & softening the tannins. If that hocus-pocus worked, maybe they should make barrel sized ones?

    Are big tannin molecules always desireable? Are soft tannins always desireable?

    Rick Schofield
    Port Ewen, NY

    • Rick, you raise many good points and ask many good questions. Conventions regarding ideal wine storage must all realistically have begun as anecodotal wisdom, but research has attempted to substantiate a lot of what we assume we know. Temperature, exposure to light, and humidity have all been quite heavily studied, as I expect you may know from the Wine Fridge’s marketing materials. In contrast, I don’t know of a single paper addressing the vibration question. The generally accepted rationale is that excessive motion interferes with the precipitation of sediment in tannic red wines. According to that reasoning, vibrations shouldn’t be important in storing most white wines, wines meant to be consumed very young, and/or heavily filtered wines. I’ve read in older books that vibrations can cause red wine “fatigue,” but without enough explanation for me to understand the phenomenon. Frankly, the only sort of wine fatigue with which I’m familiar comes after a full day of tasting.

      I’ve never heard of these magnetic coasters you mention. Something to put on the “look it up” list!

  2. You make sense, again. The old wine books often use nebulous words with no explanation, definition or science … which is why some people don’t care to get immersed in the learning about wine, it’s too esoteric.

    The wine bottle magnets (out at least 5 years now, several brands) claim to age & soften young wines (google “magnetic wine ager”). Another senior buyer & I tried one out, at our store, live, in front of the wholesaler rep.

    They remind me of the Water Softener Magnets you clamp to your household pipes instead of using the Ion-exchange tanks that regenerate with salt. Supposed to be no maintenance & just as good.

    The vibration question, in barrel, and in bottle, would be a great project for you because it has not been done before! And I am now curious for the answer.

    The vibrating barrel study could be done while in school but a vibrating bottle study, like screwcap research could take 10 years!

    Rick Schofield
    Port Ewen, NY

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