Tannins: What's going on?

[Michel_Abood]

I just read this very interesting article about the state of tannin knowledge, or lack thereof (my personal favorite was the “freaking nightmare” quote):
http://tinyurl.com/yk6n2um" onclick="window.open(this.href);return false;

Any winemakers want to discuss?

[Jim_Cowan]

Michel,
Jamie Goode has reported on some of this work that was being done in Oz.
I suppose one could say the jury is still out but, what I am reading (this article included) makes a certain sense.
Best, Jim

[larry_schaffer]

Certainly interesting stuff, and Jim Harbertson and Doug Adams sit at the forefront of practical research in this area. There is no doubt that what we thought to be ‘conventional wisdom’ with regards to tannins and tannin management will be turned on its head over the next decade or so, as better instrumentation - and better research - will be performed both here and in Australia . . .

One point not talked about in the paper but that also should have been noted is the role of polymeric pigments in the softening of tannins over time. These occur when tannins bind to anthocyanins, creating color stable molecules that are responsible for long term color in red wines . . . and also for ‘softening’ of tannins over time. By adding the anthocyanin molcule, these same tannins have been shown to have a much weaker affinity for binding with salivary proteins . . . and therefore are not nearly as astringent . . .

I could go on, but have to get back to crushing/pressing/adds . . .

Cheers@

[Jim_Cowan]

@larry schaffer

One point not talked about in the paper but that also should have been noted is the role of polymeric pigments in the softening of tannins over time. These occur when tannins bind to anthocyanins, creating color stable molecules that are responsible for long term color in red wines . . . and also for ‘softening’ of tannins over time. By adding the anthocyanin molcule, these same tannins have been shown to have a much weaker affinity for binding with salivary proteins . . . and therefore are not nearly as astringent . . .

Larry,
About three years ago, I went to some trade event at Copia and, during one of the many ongoing lectures that one could attend, was one on this very subject. I will never forget this young, very diminutive woman speaking about it and answering questions with an obviously comprehensive understanding of the subject. What floored me was that she worked for a very large winery and they were already planning around these perameters.
Humbling and enlightening.
Best, Jim

[Michel_Abood]

@larry schaffer

Certainly interesting stuff, and Jim Harbertson and Doug Adams sit at the forefront of practical research in this area. There is no doubt that what we thought to be ‘conventional wisdom’ with regards to tannins and tannin management will be turned on its head over the next decade or so, as better instrumentation - and better research - will be performed both here and in Australia . . .

One point not talked about in the paper but that also should have been noted is the role of polymeric pigments in the softening of tannins over time. These occur when tannins bind to anthocyanins, creating color stable molecules that are responsible for long term color in red wines . . . and also for ‘softening’ of tannins over time. By adding the anthocyanin molcule, these same tannins have been shown to have a much weaker affinity for binding with salivary proteins . . . and therefore are not nearly as astringent . . .

I could go on, but have to get back to crushing/pressing/adds . . .

Cheers@

That would explain the “age-softening” of tannic wines. I find the discussion about which tannins are preferable, seed or skin, very interesting.

[larry_schaffer]

@Jim Cowan

@larry schaffer

One point not talked about in the paper but that also should have been noted is the role of polymeric pigments in the softening of tannins over time. These occur when tannins bind to anthocyanins, creating color stable molecules that are responsible for long term color in red wines . . . and also for ‘softening’ of tannins over time. By adding the anthocyanin molcule, these same tannins have been shown to have a much weaker affinity for binding with salivary proteins . . . and therefore are not nearly as astringent . . .

Larry,
About three years ago, I went to some trade event at Copia and, during one of the many ongoing lectures that one could attend, was one on this very subject. I will never forget this young, very diminutive woman speaking about it and answering questions with an obviously comprehensive understanding of the subject. What floored me was that she worked for a very large winery and they were already planning around these perameters.
Humbling and enlightening.
Best, Jim

My guess is that it was Theresa Heredia, now winemaker for FogDog, Phelphs Pinot label. Phelps employs the analysis to help determine when to pick and gives them indications as to blending options . . .

Cheers!

[M_Smith]

According to Tim Patterson

Seed tannin can be extra-astringent when its terminal unit is a gallic acid ester, which doesn’t happen with skin tannins. But Harbertson observed that gallic acid is easily hydrolyzed and removed in winemaking, making that temporary astringency moot.

Characterizations such as the above make me wonder whether the author is inadvertently imprecise? I suspect he means that gallic acid ESTERS are easily hydrolyzed; not gallic acid itself?

See, for example:

[> http://tripatlas.com/Tannin> ] At the center of a hydrolyzable tannin molecule, there is a polyol carbohydrate (usually D-glucose). The hydroxyl groups of the carbohydrate are partially or totally esterified with phenolic groups such as gallic acid (in gallotannins) or ellagic acid (in ellagitannins). Hydrolyzable tannins are hydrolyzed by weak acids or weak bases to produce carbohydrate and phenolic acids.
Examples of gallotannins are the gallic acid esters of glucose in tannic acid ('C’76’H’52’O’46), found in the leaves and bark of many plant species.

According to Tim Patterson

Size matters for astringency
While much remains mysterious, we do at least know that the notion of a linear progression toward longer polymers isn’t the defining story. And it’s a good thing, too, because if that were the story, wine would get more and more “tannic” as it aged.

The feeling of astringency is produced when tannins grab the proteins from saliva, lessening the lubrication in the mouth and making tissue scratch against tissue. Research in France in 2003, conducted by Stéphane Vidal, Véronique Cheynier, Ann Noble and others, using model wines in which the tannin composition could be controlled, demonstrated through tasting panels that longer tannin chains register as more astringent than shorter ones.

See for example: http://www.ajcn.org/cgi/content/full/81/1/330S" onclick="window.open(this.href);return false;

Whereas ETS Labs explain: ETS Labs" onclick="window.open(this.href);return false;

The concentration of tannin in wine is the result of a balance between the amount of extractable tannin in grapes, extraction of grape tannin during fermentation/maceration, tannin additions, and tannin precipitation.

Tannin precursors form (relatively reactive?) tannins, many of which in turn become less reactive and/or eventually precipitate out of solution. I’m not so sure yet that previous (dogmatic?) interpretations have been decisively overturned as much as our language and concepts about complex polyphenol chemistry are rife with semantic ambiguities and apt to remain so for quite some time. Studying heterogeneous polymer chemistry can be a fast track to frustration.