THE FRUGAL OENOPHILE
Wine Appreciation through Education
email newsletter: june 2005

The Marangoni Effect

Sometimes I'm bewildered by the way people handle information. For example, I'm frequently asked to explain the phenomenon of "legs". I've tried, in my wine lexicon, to give an adequate account of legs, and in tastings I will often just quote from the book. But it seems that some people are determined to take the exact opposite interpretation. So what I'd like to do is give a full account of the issue so I won't have to answer this question ever again.

According to the Oxford Companion to Wine, legs were first explained by British physicist James Thomson in 1855. However, as sometimes happens in the scientific publishing world, the work was overlooked. When Marangoni published a similar paper in 1871, he was credited with the breakthrough, and thus his name is attached to the topic.

So what is the Marangoni effect?

When you swirl wine in a glass, the wine forms a sheet on the inside of the glass. This coating then forms rivulets as it falls back into the glass. The effect is variously called legs, tears, arches, church windows, and probably a lot of other things. We're all familiar with legs, but the question that needs to be answered is: What can legs tell us about wine?

A popular explanation is that legs demonstrate quality in wine, and this is the issue that I'd like to deal with here. To understand the meaning -- the proper interpretation -- of legs, it's necessary to understand why they come about. This brings up the next popular misinterpretation of legs: that they indicate the extract and glycerine content of wine, and that the slower the legs, the better the wine.

Here's where the popular theory begins to break down. There isn't very much glycerine (a.k.a. glycerol) in table wines. Most have about 5-10 grams/litre (g/l). But it requires a content of at least 25 g/l before glycerine has any effect on viscosity. So the glycerine content of your typical dry table wine cannot possibly influence the wine's legs.

The other notion, extract, is dispelled when you look at low alcohol wines. These always have less pronounced legs, regardless of total amount of extract. So extract can't be the issue either.

When examined in the laboratory, it turns out that legs are caused by the different evaporation rates of water and alcohol. Table wine is roughly 85% water and 12-14% alcohol. Alcohol is thinner than water and evaporates more quickly. So when you swirl your wine and watch the sheets of wine form tears, you're seeing the water fall back into the glass as the alcohol evaporates. In fact, you'll find that pure water has no tears, nor does pure alcohol, because there is no "differential evaporation rate" in pure liquids.

Here, finally, we have a useful piece of information. More alcohol takes longer to evaporate, so the higher the alcohol content, the slower moving the legs and vice versa. Some wine training courses even include a segment on estimating alcohol content by evaluating the legs. Not a bad parlour trick, although you can get the same information from the label fairly easily.

The tears phenomenon is actually quite complex as there are many factors that influence it, none of which is wine quality. There's the actual alcohol content of the wine. There's also the tendency of wine to hold onto the glass's surface. This is further affected by temperature and the condition of the glass. The higher the temperature, the faster the evaporation, and the thinner the legs. As for the condition of the glass, cleanliness is a big factor. Film on the glass will determine the legs far more than will wine quality.

Another misconception about legs is that the wine is actually creeping up the glass. Nice bit of fiction here, but this is physically impossible. There is a certain amount of surface tension that can cause wine to rise ever so slightly, but to actually crawl up the glass? Not likely.

What does this all mean?

Legs do not have anything to tell us about wine quality. If wine has alcohol -- and it always does -- then it will have legs. Good wines have legs, great wines have legs, and bad wines have legs.

Legs do not indicate viscosity caused by glycerine. There is very little glycerine in table wines, far too little to affect a wine's legs.

Legs are affected by alcohol content, and also by the condition of the glass. In fact the legs in your glass may tell you more about your dish detergent than about your wine.

So the next time you hear someone praising a wine because of its great legs, don't bother to correct them. It won't do any good. Instead, be content that you know the real reason for legs, and that you'd never make the mistake of equating legs with quality.

What about sweet wines? Well, all bets are off here. Sweet wines contain rather large amounts of glycerine, 25 g/l or more. This will affect the viscosity of the wine, and therefore will affect the legs as well. But rather than make the issue simpler, you now need to consider glycerine, alcohol content, temperature, and the condition of the glass. So once again, legs don't help us to conclude anything about the wine. Sorry.

Semantics Some people prefer the term glycerol to glycerine. They are often used interchangeably to refer the same sweet, viscous substance that is found in minute amounts in dry wines.

One Step Forward...?

Winemakers in Alsace have won the right to exclude grape names from their Grand Cru wines. And they're happy about that!

Although I don't advocate rampant varietalism, one nice thing about Alsace labels is that they tell you both "what" and "where". So an Alsace Gewurztraminer is gerwurztraminer from Alsace. Simple. If burgundy winemakers, for example, would write Pinot Noir or Chardonnay on the labels as well as their appelation names, it would be a big help. Now the one advantage we geographically challenged had will be revoked, and we'll have to hit the books to find out what Alsace is offering. My guess is that the move will alienate a lot of North American buyers, who are used to looking for varietal labels and who are somewhat averse to trying to decipher traditional French labeling.

Online Store Now Open

All my "busy-ness" has resulted in a number of educational products that I would like to get into the hands of wine lovers. I'm now testing an online shopping cart system on my website to make these items available more easily. The site uses PayPal, a convenient and secure system that makes online ordering quick and painless. I hope you'll drop by to see what's up, as well as to see a couple of non-wine products that I've helped to develop.

From "The Frugal Oenophile's Lexicon of Wine Tasting Terms"

Tartaric Acid

A component acid of most wines that tends to settle out as harmless tartrate crystals (cream of tartar). Some vintners will intentionally remove tartaric acid to prevent crystals from forming in the bottle

For information on purchasing my Lexicon, visit www.frugalwine.cam
Or purchase it on-line at www.chapters.indigo.ca

The Other Down Under

I'm pleased to report that New Zealand's winemakers are out of step with current wine trends. In a market that is becoming dominated by over-blown, ultra-premium wines and non-descript "popular" wines, the Kiwis have decided to focus on quality and traditional values. I.e. they're out to grow the best grapes -- grapes that are suited to the terroir -- and allow them to become great wines, and at prices that most of us can afford at least occasionally.

Last month I attended a tasting that featured 12 wines from 12 wineries, 8 different regions, and 10 different grapes. The title of the event was "Sauvignon Blanc and Beyond," signifying that New Zealand is skilled at not only at Sauvignon but at other varietals as well.

At last year's New Zealand show (which, by the way, was also fantastically well organized by a capable team led by Robert Ketchin) the varietal of the moment was Pinot Noir, the idea being that the world knows that Kiwi sauv blanc is the absolute best ... "but have you tried our pinot?" This year's goal was to show us what the careful matching of grape variety to terroir could accomplish. And the results are very impressive indeed.

We started off with three sauvignon blancs, from Kim Crawford, Wither Hills and Sacred Hill wineries. As expected, these were huge, spot-on varietals showing all that juicy character you expect from NZ. The style seems to be a little better controlled this time out: meaty and satisfying. Next was a pinot gris from Matakana Estate, near Auckland. This one showed a subtle-though-complex fruit salad on both nose and palate. I didn't expect to see a gewurz, yet there it was, from Villa Maria in the Gisborne region. Here the nose upstaged the palate, showing incredible varietal authenticity.

Not to be outdone by the aromatics, Morton Estates' Black Label Chardonnay showed everything you expect -- and want -- in an oakey, spicey chard.

Three pinot noirs led off the red wine grouping. The first, from Seresin, I'm guessing was too far down the cue. Having sat out for more than an hour by this time, it seemed rather faded. Too bad, because it probably had much to offer earlier. The Voss Estate and Mount Difficulty pinots fared much better. I flagged the Voss as a good candidate as a gift wine for a connoisseur, while the somewhat lighter Mount Difficulty might be better left in the cellar for another year.

Paul Giamatti notwithstanding, the Bullrush Merlot from Mattua in Hawkes Bay showed oodles of dark fruits and spice, splendid for now or for a bit of cellar time.

CJ Pask opted for malbec in their bordeaux-style blend of cab/malbec/merlot: amazing complexity, lush and elegant, but really too young to show its stuff. Last up was Trinity Hill's Gimblett Road Syrah. This too was still a toddler, but the rich spice, oak and berry nose and fat, luscious palate alluded to what awaits a patient buyer.

As if these wines weren't enough of a treat, we were told that all will be available through standard Ontario channels during 2005. Better still, the prices ranged from about $15 to just under $40. My complaint about last year's offerings was the "ultra premium" pricing on all the wines. It's nice to see a more compassionate pricing policy, especially at this quality level.

So keep a look out for these wines and for these winemakers. No doubt the same degree of quality can be found throughout their wine list.

100% New Zealand! NZWines.com

Inspirational Quote

Legs are the Lava Lamps of wine tasting; they provide contemplative amusement, but shed precious little illumination on the subject at hand - Jim Lamar (winepros.com)