Cork vs screwtop

In 2001 Tinhorn Creek, a fairly well -reputed BCwinery, did an experimental bottling of the Sandra Oldfield Merlot,their reserve bottling, half with cork and half with screwtop closures. We bought a 6-pack, 3 of each closure.
We tried our last bottle of each this week.
The screwtop was first up and showed a typical Merlot nose of red fruit and cocoa. The fruit was fresh and sweet, with reasonable length and the wine was better than we had anticipated for Tinhorn Merlot.
Tonight, the cork version. The nose still said cocoa, but less fruit. In the mouth, muted fruit and lots of oak. Much inferior to the screwtop.
I don't know why the screwtop should have much brighter fruit and to have eliminated the oak, which dominates many BC wines. Does anyone have an explanation?

If you try the search engine, you'll find reams and reams of posts on this subject but, essentially, corks allow varying amounts of oxygen into the bottle, gradually killing the fruit of any but the most special wines.

I don't know why the screwtop should have much brighter fruit and to have eliminated the oak, which dominates many BC wines. Does anyone have an explanation?

Yes. See this quote from Tom Stevenson's article about Riesling (hence the emphasis on TDN) http://www.wine-pages.com/guests/tom/ri ... trol-2.htm
Interestingly, according to tests conducted by AWRI, natural cork closures absorb as much as 50% of the TDN found in any wine, while Altec and "One + One" technical corks can remove as much as 70%, and the most absorptive synthetic closures no less than 98%! Screwcaps actually preserve TDN, but I'm a screwcap fan, and TDN is not the only thing that corks absorb. Cork also absorbs numerous other flavour volatiles. So much so that the industry employs a "flavour scalp factor" as a measure of cork's flavour volatile absorption potential, and this scale is measured by highly accurate SPME-GC-MS analysis.
Well - OK - not really an explanation, but an indication that it is a well-known effect.

Not sure why the screwtop would eliminate oak. My guess would rather be that the cork added a woody flavour.

Yes. See this quote from Tom Stevenson's article about Riesling (hence the emphasis on TDN) http://www.wine-pages.com/guests/tom/ri ... trol-2.htm
Interestingly, according to tests conducted by AWRI, natural cork closures absorb as much as 50% of the TDN found in any wine, while Altec and "One + One" technical corks can remove as much as 70%, and the most absorptive synthetic closures no less than 98%! Screwcaps actually preserve TDN, but I'm a screwcap fan, and TDN is not the only thing that corks absorb. Cork also absorbs numerous other flavour volatiles. So much so that the industry employs a "flavour scalp factor" as a measure of cork's flavour volatile absorption potential, and this scale is measured by highly accurate SPME-GC-MS analysis.
Well - OK - not really an explanation, but an indication that it is a well-known effect.

This is a very interesting article. I, for one, did not realize that the flavour development of wine was so profoundly influenced by the properties of closures other than by their different abilities to let in air and to develop TCA. (Of course, under natural cork, the same wine differs from bottle to bottle even without detectable TCA). This points up even more the need for comparative studies of the flavour behaviour of really fine age-worthy wine under the different types of closure over many years.

There is no doubt that such really fine wine so matured under a GOOD natural cork can develop extraordinary qualities. Screwcaps still do not have a sufficient track record to prove that such wines develop equally well under them in the long term, although many people seem prepared to bet on that being the case. Maybe the cork's "flavour scalp factor" plays a part here in allowing the development of secondary complexities, whilst penalizing wine designed to be drunk young.

Re the apparent elimination of oak under screwcap, I wonder whether its presence was not simply masked by the more vigorous fruit.

Re the apparent elimination of oak under screwcap, I wonder whether its presence was not simply masked by the more vigorous fruit.

I believe that is precisely the case, Tim: a case where the essential balance of the wine was altered, simply because one element's absence (fruit) showed the emergence/dominance of another element (oakiness).

Based upon what I've experienced, and what winemakers I trust have told me, the screwcapped version is likely closer to what the winemaker intended the wine to be than the cork-finished version.

Experiments like this are generally poorly controlled. The fillers, bottles, and tanks all have to be changed over- it's different that (say) tree bark versus synthetic cork. There are a lot of places where one can suffer inadvertent oxygen pickup.

Another variable is winemaking and bottling practice- if you optimize for one type of closure, you will not be optimized for the other. It's like running a race between a diesel and a gas engine, but using the same fuel for both.

One other factor is extractives- tree-bark corks definitely impart extra oak notes to wine; I've noticed this in both soak tests and numerous side-by-sides with screwcaps, synthetics, and tree-bark cork.

One other factor is extractives- tree-bark corks definitely impart extra oak notes to wine; I've noticed this in both soak tests and numerous side-by-sides with screwcaps, synthetics, and tree-bark cork.

I'm not sure how significant it is, but of course cork is not just tree bark - it is OAK tree bark.

Well, if you want to be specific, it's Quercus suber bark. But that's sort of implicit by the use of the word "cork"; I'm just trying to distinguish it from "low density polyethylene cork."

I was just suggesting that the fact that cork comes from oak trees makes it less surprising that they might add an oaky flavour.

Ah, gotcha. Yes, absolutely true. Sound corks have an aroma very reminiscent of barrels, vanillin and all.