I recently attended a seminar by UC Davis professor Dr. Andrew Waterhouse who was giving updates of various research projects at the university. Are you aware of the Tannin Assay that has been recently developed? I had posed a question to him about the assay that wasn't answered to my satisfaction so I thought I would direct it to you. (Let me preface by stating that I am just a lowly MW student, so my understanding of the subject is surely more limited than that of a trained winemaker)
I had asked him if the assay, which is protein based, would quantify the total tannins or just the astringency of tannins. He said there was no distinction between the two, tannins = astringency. Based on much of what I've read about bookending tannins, micro-ox, etc. this seemed hard for me to believe.
To add to the debate, just this morning on Jancis Robinson's member forum I was reading an account that Dr. Boulton was lecturing in Spain and made the statement that there is not such a thing as “ripe or green tannin”; research shows that what we call ripe or unripe tannin is just amount of tannins.
Can you weigh in from your perspective?
Well, I certainly disagree with both of these learned men. Jeez, don't get me started.
To me the differences in tannin which I was taught by Patrick Ducournau, and regularly observe and teach are as obvious as the color of the sky. You don't need an academic argument. Just taste some wines. I'm not sure what is meant by "ripe" tannins, but the term "tannin verte" has been used for at least fifty years at the University of Bordeaux and is discussed in Peynaud's book, The Taste of Wine. It's in everyday use with any decent French oenologiste, along with "dur," "fondue," and "sec." It doesn't mean unripe -- all young wine has green tannin, which then either converts to hard via oxygenation or to dry if it is deprived of it or if too much hangtime has occurred.
There is absolutely no evidence to support these men's point of view on tannins, and Dr. Adams' results make it plain that the position is indefensible. In addition, every other winemaking university says otherwise. Chief among them is the Tannin Wheel developed by Richard Gawel at the University of Adelaide, which specifies forty different tannin descriptive terms, and was developed in collaboration with the University of Stellenbach and Prof. Michel Moutounnet at Montpelier.
Dr. Boulton, under whom I served as teaching assistant, is a chemical engineer, a damned good one, but unqualified in this area, although he did some brilliant work elucidating the phenomenon of copigmentation, which paradoxically is probably the source of what we call green tannins. If you put the question to Roger, are copigmentation colloids, which he demonstrated are 100% monomer, trisant in wine, he'd say yes. But he's never considered that this structural change in the wine might cause a difference in astringency from green to hard. It's not his area.
Dr. Waterhouse is an analytical chemist. Neither of them have sensory training nor do they do research in this area. They are both spouting the gospel according to Ann Noble, the queen of Davis astringency research. Ann did excellent work on time-intensity of astringency in the 80's, and took the position they espouse early on, seeming to want her work, which had nothing to do with distinguishing types of astrigency, to be the final word on the subject of astringency.
I once tried to teach Ann the differences in tanins, bringing examples for her to taste. She insisted on "cleansing her palate" before each taste by rinsing her mouth with some disgusting protein gunk, after which she couldn't discern anything. She makes her sensory subject do the same thing. Consequently, she has failed to reproduce the tannin types in her experiments. Two habits pervade Davis. One is that they think that failing to show a difference is the same thing as proving there isn't one. Secondly, they are not really a member of the international community, and don't trust any work that isn't done at the Wickson Hall ivory tower, feeling that the French and Australians aren't real scientists.
Waterhouse seems to be unaware that Doug Adams' work with microoxygenated wines in our collaborative study in 1999, which showed an increase in SPP (stands for "short polymeric pigment") as well as LPP in young wines. Doug (it's his assay) and his assistant Jim Harbertson were very surprised, as they had never before observed SPP increases. These are the polymerized protiens that aren't precipitated by the test protein. Since the oxygenation softens the tannins, it showed that in reality, Doug's assay tests for astringency rather than polymer, as you were asking. But I guess Andy wasn't in that loop.
So you have the answer to your question. In general, LPP is over tetramer (4 units daisy-chained together or more), but in wines where oxygenation, lees stirring or other enrobage strategies soften the tannins (without changing the total amount) SPP grows during the treatment. In young reds, the LPP grows too, because monomer is being polymerized, but once the monomer is used up after a year or so, it shrinks, indicating a softening (loss of afinity for binding to protein, be it salivary mucins or the bovine serum albumin in the assay).
Well structured wines go from hard grippy tannins to soft, enrobed tannins as they mature, and then dry out when the wine goes over the hill. At that point, astringency (and LPP) increases again, despite that the total tannin is remaining constant or even decreasing through precipitation.
I recommend you talk to Doug Adams or to Jim Harbertson about the assay. Andy and Roger aren't really qualified to discuss it. You can also read about the assay on my website, where we recommend it for grape maturity determination. If you want to know if tannins have different characteristics, taste some wines. It's perfectly obvious.
But there are none so blind as those who will not see. Frankly, I gave up on these guys a while ago, and recommend you do the same.