Question on Grape vs Oak Tannins

Sometimes I read wine descriptions that distinguish between the tannins that come from grapes vs the tannins that are present in wine from the oak barrels. I think it is pretty easy to recognize the flavors that come from new oak, such as vanilla, barrel lactones like coconut, caramel, toast or Pain Grille as RP calls it. Some flavors are harder to tell (for me) if they come from the grape or barrel, like the "Baking Spices" or "Oriental Spices" described in Vosne Romanee for instance.

But getting back to my question. I realize that tannins are more of a mouth feel than a true flavor. Can the tannins from oak be distinguished from the grape tannins? Are they more drying? If there are significant tannins from new oak, wouldn't they be noticeable in white wines that are aged in new oak?

Thanks in advance for your thoughts.

Best,
Marc

I never really noticed, but it's an interesting question so I poked around. Here's one article which says they affect ML differently: http://www3.interscience.wiley.com/cgi-bin/abstract/72513595/ABSTRACT?CRETRY=1&SRETRY=0. And here's another paper which will make you sorry you asked, but I think it answers the question: http://www.vinquiry.com/pdf/ENOLOGICAL%20TANNINS%20Article.pdf. And to quote Ms. Robinson: "Oak tannins different in significant ways from grape tannins, although the consequences of such differences on the stability of wine colour and and on the sensory properties (including mouthfeel) of barrel-matured red wines are yet to be scientifically rationalized." (The Oxford Companion To Wine, 3rd Edition, p. 680)

Sometimes I read wine descriptions that distinguish between the tannins that come from grapes vs the tannins that are present in wine from the oak barrels...Can the tannins from oak be distinguished from the grape tannins? Are they more drying?

I could be mistaken, but have always felt that grape tannins grip/affect the front of the mouth and gums to a greater extent than wood tannins, which grip the inside of the cheeks and the sides of the tongue.

An easy test: next time you get table grapes (or wine grapes), take a few stems and chew
on them. The grape tannins will extract pretty quickly and you can use that as a basis
for comparison.

What's kind of striking (to me) is how mellow the oak tannins are in comparison. I once steeped
an ounce or so of French and American oak chips from the winemaking shop in vodka (separately, in
two old wine bottles) for a month so I could test the differences between the varieties. Both had
nearly overwhelming (and different) oak character, but very little tannin. Compare also single-malt
scotch, no grape tannins but aged for years in oak; I personally don't find any tannin in scotch.

I find them very different in texture. I find wood tannins to be very soft and mouth-coating, whereas grape tannins I find to be robust and refreshing. I am interested to know why this is.

-O

Gary,
Thanks for the links. The first one didn't work, and I found the second one a little shocking. I knew there was all kinds of additives used in wine making, but had no idea you could add different types of laboratory manufactured/extracted tannins.

Robert,
When I drink Nebbiolo based wines, I notice the tannins have a teeth and gum coating quality to them. Maybe that is the grape tannin.

Ernie,
Will give this a try, thanks. Have you ever added tannin extract to any of the wines you made?

Otto,
Thanks for your description. Do you find the oak tannins more astringent? Can you tell there are oak tannins in the wine when you notice the tell tale aromas of new oak?

Best,
Marc

Otto and Robert... when you describe oak and grape tannins, aren't you really describing the tannins in oaked and unoaked red wines? If not, how do you know the origin of the tannins you are describing?

To me it seems the evidence that oak tannins contribute little to mouthfeel is pretty overwhelming. We have Marc's observation that oaky white wines are rarely very astringent. And Ernie's vodka expermients and observations on whisky.

Oh, and BTW here's a working version of Gary's first link: http://www3.interscience.wiley.com/cgi- ... 5/ABSTRACT

Otto and Robert... when you describe oak and grape tannins, aren't you really describing the tannins in oaked and unoaked red wines? If not, how do you know the origin of the tannins you are describing?

Well, now I am thoroughly confused. I was going by what I have heard from several different wine producers. In our yearly wine fair, such conversations have come up with people representing Gruaud Larose, Drouhin, Niepoort and probably several other producers. I was relating the experiences I had in these tastings and the thoughts expressed there to what I drink, since I assumed that producers/winemakers would know what they are talking about. And one more point of confusion: I thought I was saying pretty much the same thing as Ernie with the Vodka experiment. I guess more than anything, this is a good case of not trying to make sense of anything at 2am with c.2/3 of a bottle of wine drunk because I don't see the problem.

-O

Maybe you were saying the same of Ernie, Otto, but I interpreted your "soft and mouthcoating" tannins as something more noticeable than what Ernie wrote about.

When it comes to winemakers/producers knowing what they are talking about... in this instance I would not be convinced. I doubt most of them know or care the origin of the tannins that they perceive - they adjust the oak until they get the effect they want but who is to say that what they perceive is oak or grape tannin. As you probably know by now, Otto, my default postion is usually scepticism/cynicism

Steve:

There are also wine-makers who are very attentive to the type and quality of tannins they end up with in their wines. Grape tannins come from the skins, and particularly astringent tannins come from the seeds and the stems (if you ferment with all or a portion of the stems). To minimize grape tannins (and still get a good extraction of color from skins) wine-makers use a pre-fermentation cold soak, total elimination of stems, "delestage" (i.e "rack and return" whereby the juice is racked or drained and then returned to the fermenter during primary ferment to aerate the must, and a sieve is used to remove as many seeds as possible) and a cooler fermentation and shortened or eliminated post ferment maceration (i.e. the period of time where the juice is kept in contact with the skins after most of the sugar has been converted to CO2 and alcohol).

marco

I said myself, Marco, that winemakers know how to manipulate the variables to get the effect they want.

But it is yet another step completely for them to be able to say, e.g., "That nicely textured tannin at the front of the mouth comes from oak". There are simply to many confounding factors to make such assertions with authority without a lot of research. And I am sure winemakers have better things to do to occupy themselves.

I did try adding some grape tannins to a batch of syrah, but I was too conservative and the
small dosage didn't contribute much. Actually, that batch is a good example: it was much too
soft and I tried to add some structure by oaking it heavily (in addition to the grape tannins),
and I ended up with, basically, oak tea with the same softness. Two years on and it's just
beginning to drink acceptably.

Just as an aside, it is my understanding that only relatively new oak leaches tannins. The question thus arises as to the age of the barrels, oak chips, oak staves, and other oak barrel alternatives. If, for example, chips have been made of old, recycled oak and re-toasted to impart that particular toasty element, then they will probably not impart tannins as do new oak barrels.