A Feather in Their Caps: Experimenting with closures at Paumanok

By Tom Mansell, Science Editor

In our annual wines of the year tasting, the NYCR staff tasted many, many delicious wines. One of the big winners of the day was Paumanok Vineyards, whose wines swept the three Long Island categories in which they were nominated -- Merlot, White Wine and Ice/Dessert Wine).

Interestingly, all three of the winning wines (and a fourth wine that was also nominated in the white category) were bottled under screwcap closures. All of the submitted wines showed interesting and in some cases unique aromas and flavors, often bordering on exotic and tropical.  

The Wines

The NYCR tasting note on Paumanok's 2009 Sauvignon Blanc read: 

The nose is extremely tropical -- typical of the sauvignon blanc musque clone -- with aromas of papaya, passion fruit, peach and mandarin orange with just a subtle grassy note beneath that fruit cocktail.

Similarly, when I tasted the 2009 Late Harvest Riesling during our wine of the year tasting, it showed a powerful tropical and stonefruit profile in addition to a spicy botrytis edge. It was so aromatically charged that a few of us (tasting blind) thought it could have been a muscat or gewürztraminer.

While I agree that clonal selection contributes to the tropical aromas, I would submit that the closure may also play a role.

Screwcap closures, specifically of the tin-lined variety, allow almost no oxygen to enter the wine after bottling. I don't want to get too much into the chemistry of sulfur in wine here (if you do, you can check out a piece I wrote not long ago for Palate Press). Briefly, there are many sulfur-containing compounds present in wine.  Some are pleasant, including 3-mercaptohexanol (passion fruit/grapefuit) and 3-mercaptohexyl acetate (guava).

These compounds make up a large part of the varietal character of sauvignon blanc. Reductive conditions in the bottle (i.e., the absence of oxygen ingress) can help maintain these sulfur-containing compounds in an aromatically-active state.

Another important sulfur-containing compound found in wine is dimethyl sulfide, or DMS. At low concentrations, DMS can intensify berry aromas. From the NYCR tasting note for the winning Paumanok 2007 Tuthills Lane Vineyard Merlot:

Intense aromas of blueberry, black cherry and black plum fruit are accented by vanilla bean, sassafrass spice, violets and speck.

Bold, but well balanced on the palate, there are gobs of dark fruit here -- blueberry, plum, cherry and even a little fig -- with layers of cola and spice and vanilla and violets and cured/smoked meat. The spiciness leans toward the exotic, with sassafras coriander seed and sumac.

While I don't exactly know what "speck" is, I do know that DMS increases with bottle age and in some cases has been shown to increase more rapidly in bottles sealed in screwcaps. Again, it's possible that the closure could have played a role in the wine's aroma profile.

Before this piece comes off as a rousing endorsement of screwcaps, I should mention that these closures are not without their problems.

A typical complaint about bottles sealed under screwcap closures is what is broadly called "reduction", but more accurately known as "sulfur-like off aromas." These aromas range from a rotten egg-like smell (hydrogen sulfide) to cabbage and rubber (mercaptans) and garlic (sulfides). An excess of sulfides like DMS, for example, can lead to a canned corn and/or low tide aroma in wines. 

This is not to imply that screwcaps "cause" reductive aromas. More precisely, the oxygen-poor environment that they create and maintain makes it easier to observe the sulfur-containing molecules that make their way into the bottle (for better or for worse... better for tropical aromas, worse for rotten eggs).  

Luckily, the aroma of hydrogen sulfide in bottled wine is easily taken care of via aeration or decanting. The mercaptans and sulfides, however, are more persistent, and won't simply "blow off."

I recently opened a bottle of Paumanok's 2008 Chenin Blanc during a chenin tasting and found a bit of reduction on it that did not go away over the course of the evening. The 2009 Chenin Blanc showed well at the WoTY tasting with a nice peach iced tea note, but there may have been a reductive note creeping in there as well. Surely, radically changing a wine's exposure to oxygen has a bit of a learning curve.

Paumanok Uncorked 

Paumanok started bottling wines under screwcaps three years ago. Today, all of their whites and rosés, most of their dessert wines, and even some of the reds can be found under screwcap. I talked with Paumanok winemaker Kareem Massoud (pictured right surgically removing a broken cork from a 1993 local red) Long Island  about the wines and the decision to use an alternative closure.

Massoud told me that part of the motivation for bottling aromatic whites and other wines with screwcap closures is simply avoiding cork as a closure. He cites Randall Grahm, saying that "any bottle of wine with a cork in it is corked." While this statement is likely to get you in trouble if you ever travel to Portugal, at the heart of the matter is the presence of haloanisoles like TCA (commonly referred to as "cork taint") in corks.  

Most serious wine drinkers can tell when a wine shows the musty, stale aroma of cork taint (estimates of proportions of "corked" wines can range from 2% to 5%).  However, Massoud seems more worried about when TCA's effects are more subtle. He astutely points out that even at levels below the detection threshold (which is remarkably low), TCA can suppress the perception of fruit. In other words, at low TCA levels, wine may not smell "corked", but rather display an absence of fruit... or just seem "off."

So in response to my question about the fruitiness of the wines in question, Massoud, one of the most technically savvy winemakers I have met in the industry, cites the lack of cork as a possible reason. He also stresses that meticulous viticultural practices (e.g., cluster thinning, leaf removal etc.) produce the best grapes and cleanest juice, leading to a ripe fruit profile.  

Basically, working hard to bring in the ripest fruit possible goes a long way.

The "sulfur off-aroma"-causing molecules generally arise from an abundance of hydrogen sulfide (generated by yeast) during fermentation.  "I'd be lying to you if I said I wasn't concerned about sulfides." says Massoud. He goes on to say that it's just good winemaking to manage sulfides during fermentation. The fewer sulfides that show up in the fermentation, the fewer will make it into the bottle. Active monitoring and management of fermentations in the cellar can mitigate the risk of these aromas.

Paumanok is also experimenting to observe the effects that screwcaps on the aging of their wines. Several bottlings (including Tuthills Lane Merlot) have been bottled under both screwcap and cork for comparison.  

The library of screwcapped wines is shallow to date, but continued observation will guide decisions about future bottlings on screwcaps. For example, it seems too early to say how some of the reds will age under screwcap vs. cork, or which varieties are more suitable for screwcaps over the long term.   

Interestingly, because of their radically different oxygen transmission rates, screwcapped wines are bottled with a smaller amount of sulfites than those sealed with cork. It will be intriguing to see how these wines compare in five to ten years or more.

The choice of closure is just one of a plethora of choices that growers and winemakers make from budbreak to bottling. As one of the most innovative wineries around, Paumanok is judiciously using alternative closures in an attempt to deliver the best wine that they can.  And in most cases, especially the Sauvignon Blanc and Late Harvest Riesling, it's working out exceedingly well.

Further Reading:

Segurel et al., Contribution of Dimethyl Sulfide to the Aroma of Syrah and Grenache Noir Wines and Estimation of Its Potential in Grapes of These Varieties, J. Ag. Food Chem., 2004

Brajkovich et al., Effect of Screwcap and Cork Closures on SO2 Levels and Aromas in a Sauvignon Blanc Wine, J. Ag. Food Chem., 2005

Brimstone in the Bottle: Sulfur Compounds in Wine

Comments

[Lenn Thompson]

Speck is only my favorite of the cured Italian pork products. http://en.wikipedia.org/wiki/Speck

[Tambi Schweizer]

It will be interesting to see how the same wine tastes in five years with a screw cap vs a bottle with a cork. I would love to be there for that tasting!

[Evan Dawson]

I thought we all grew up singing that classic song:

"Once there was a Dutchman, his name was Johnny Roebeck, and he was a dealer in sausages and speck..."

[Kevin Welch]

Tom, I'm curious, in your research did you find that wine makers using screw cap closure also tend to adjust preservatives such as reducing the amount of potassium metabisulfite to compensate for the presumable more effective closure?

[Tom Mansell]

Kevin: Yes, at least Kareem Massoud does. This interesting tidbit was unfortunately buried near the last paragraph of the piece.

I have found many cases where my nose hairs have been practically burned off by the amount of SO2 in screwcapped wines. I think in many less careful winemakers continued adding the same amount of sulfites after switching from cork to screwcap, operating as if nothing had changed. Changing the closure is a big adjustment, and measures should be taken to avoid problematic outcomes, for example the management of sulfides in the cellar, as Kareem pointed out.

Lenn: Interesting. There are "meaty" thiols as well, like 2-methyl-3-furanthiol, which would be preserved in the same way as the "fruity" thiols.

[Barneygrubbs]

This one looked interesting, too:
http://pubs.acs.org/doi/abs/10.1021/jf9023257
"Impact of Oxygen Dissolved at Bottling and Transmitted through Closures on the Composition and Sensory Properties of a Sauvignon Blanc Wine during Bottle Storage"

It was interesting to see that the Saranex 38 liners have polyethylene as the wine-facing layer while the Saran-Tin liners have polyvinylidene chloride (over the tin) in contact with the wine. (It seems like polyethylene would have less chance of degrading into something unpleasant over the long term than would polyvinylidene chloride, but it is also more oxygen permeable. Though in the dark without much oxygen, they're both probably fine for a long long time)

[AdamS]

Hard to correlate btw screw caps and quality in this instance since the Massouds have been making great wine at Paumanok for many years using corks and are now doing the same using both closures. Could a fabulous home-cooked meal from Ursula have anything to do with the result? Lenn plz come clean on this.

[Kareem Massoud]

Nice post Tom, thanks!

[daniel]

Great post. I'm a little curious about whether they mentioned copper additions in an attempt to avoid reductive issues. A lot of winemakers that I talk to about bottling reds under a screw cap feel that this is all but necessary.

[Lenn Thompson]

AdamS is right...about Paumanok making good wines for years. Unfortunately, I have yet to experience an Ursula-cooked meal!

[Tom Mansell]

Barney:

I'm not a polymer chemist, but I agree that I'd prefer to avoid organic halogens in general. I guess time scale is the most pertinent question. If a Cl* radical breaks off once every 10 years or so under pHs between 3-4, then it's probably not a big deal.

Then again, the polymer that's in contact with the wine is one of only about a million other things to consider in choice of closure. One could write a whole book on closures (and my wine science idol, Jamie Goode, actually has). In general, polymer-based seals seem to be quite oxygen permeable, including Saranex screwcaps, Vinoseal, et al. in addition to synthetics.

Daniel:

Copper is just one tool for managing sulfides in the winery. It would be irresponsible for a winemaker to, say, add the legal limit of copper for any wine that will be put under screwcap. In fact, as I mentioned there are lots of "good" thiols, which would also be stripped out with the mercaptans and H2S after a copper addition.

Also, disulfides are NOT susceptible to removal with copper. Disulfides can reduce over time to form mercaptans (a potential cause of "reductive" problems with screwcaps). In fact, if there were residual copper in the wine and mercaptans arose post-bottling, it could lead to a nasty black precipitate in the finished wine (copper sulfide). Plus, copper and other heavy metals are closely regulated... because they are toxic in high doses.

So there are a lot of things to consider while contemplating a copper addition. The impression I got from Kareem is that monitoring fermentations for H2S production (i.e., preventing formation of too many mercaptans/disulfides in the first place) is far more important than prophylactic copper additions.

[Kareem Massoud]

"The impression I got from Kareem is that monitoring fermentations for H2S production (i.e., preventing formation of too many mercaptans/disulfides in the first place) is far more important than prophylactic copper additions."

Tom, exactly. Sulfides are first and foremost a winemaking problem/issue/complexing factor (depending on their kind and severity and depending on one's style and palate). The fact that screw caps make a tighter seal than other closures by definition means they create a more reduced environment for the wine. And so logically it is correct that the more reduced environment will exacerbate the formation of sulfides, however, it is far less important than making sure your wine is free of sulfides in the first place (of course it's impossible to be 100% certain of this). Sulfides are not really a closure problem.

[daniel]

Thanks both Tom and Kareem for your responses. I have little formal chemistry training but this is a topic that I find both fascinating and pertinent. I agree that preemptive copper additions are irresponsible at best (seems to be a "make the foot fit the shoe" mentality), which is why I posed the question. From what I've heard and read, copper additions (when bottling under screw cap) do seem to be a wide-spread practice. Surely copper has an appropriate place in the winemaker's tool kit but I wouldn't be surprised if it were abused (knowingly or not). Beyond preventing sulfides from forming in the first place (or trying to), what does a [responsible] winemaker do to prevent issues when bottling in a reductive atmosphere? Kareem, maybe sulfides are not a closure problem but I would have to assert that reductive issues certainly should be (and are) considered as part of the closure decision.

I think screw caps have an important role in the industry but reductive issues are one of the concerns I've heard from many winemakers when considering them. It would be great to see them viewed as completely viable closure option and clear that hurdle.

[Tom Mansell]

Daniel:

"[M]aybe sulfides are not a closure problem but I would have to assert that reductive issues certainly should be (and are) considered as part of the closure decision"

I totally agree. As for managing sulfides, Kareem could probably speak to this better, but generally H2S arises from two places: (1) reduction of sulfur residues on grapes and (2) poor yeast nutrition.

It seems odd, but yeast produce more hydrogen sulfide when they are starved of nitrogen. Essentially, when there isn't enough yeast assimilable nitrogen (YAN: ammonia, amino acids, etc.) to produce biomass, the yeast starts to recycle its own amino acids. Sulfur-contaning amino acids like cysteine and methionine create H2S when they are recycled in this way.

It was common advice from Cornell (especially in the Henick-Kling era) to add the legal limit of DAP (diammonium phosphate) to fermentations to ensure adequate yeast nutrition. Nowadays, we know that adding *too much* DAP creates its own problems, including microbial stability issues, increased biogenic amine production, and the possibility of creating too much biomass... which could lead to the same sulfide problem you had in the first place. Complex fermentation aids like Fermaid O, etc. can circumvent some of these issues.

Testing for YAN is relatively straightforward if you have the proper (i.e., very expensive) equipment. The NYS Wine Analytical Laboratory will do these tests as well.

[Fabio (Vinos Ambiz)]

Apart from all the technical checmical aspects that the post itself and comments deal with, there is another much more important side to the closure debate, namely the environmental question.

I'm sure you all know already that the aluminum mining and fabrication process is one of the most polluting that exists; and that cork farming is one of the most sustainable and beneficial, both enviromentally and socially (and culturally too, if you want).

I'm perfectly happy to bear the 'cost' of sending a corked bottle back every now and then, rather than conuming yet another aluminum or petroleum-base closure, and adding to the planet' environmental problems and leaving the mess for our children and future generations to clean up.