...and I am not talking about my Champagne. Try this experiment yourself. Uncork a bottle, pour some wine out to the bottom of the shoulder, put your hand over the bottle's opening, and then shake. I bet there you wine will get a head of bubbles, to steal beer lingo. For the longest time I assumed this was because I am at an altitude of 4240ft, and that it was dissolved air from the winery that bubbled out because of lower atmospheric pressure where I live. I made this assumption because most (not all) wineries are closer to sea level than me. Then, recently, on a trip to NYC, I did the same thing, and...bubbles! So what are these bubbles, is it dissolved hydrogen sulfide gas? I have noticed that older wines have fewer bubbles. Maybe it is dissolved CO2 left over from fermentation. And, of coarse there is the occasional infected bottle with gas forming organisms. And, yes, some is due to elevation changes. Any insight to my bubble quandry?
Original Post
quote:
Originally posted by The Cabernet of Doctor Caligari:
Compare your urine at sea level and then at altitude. You may be on to something!

For the wine, I suspect by shaking you are adding gas and the bubbles are primarily the product of agitation.


Not sure about the urine, but the more I shake it, the less it fizzes (insert adolescent teenage joke here). After a few good shakes, there are hardly any bubbles left (ditto). The wine usually tastes better after the shaking as well. I think splash decanting is a more sophisticated method of obtaining the same result.
I've experienced some harmeless and some harmfull version of bubbles in white wine.
It happens quite often in youthfull Mosel wines. I tend to wait until the bubbles disappear, say after 15minutes in the glass.

Then i've had a very bad experience with some René Rostaing Condrieu la Bonette 2004. The wine had a striking lot of bubbles and the taste was really awfull, probably the worst wine experience i've ever had. Same experience for the remaining bottles of a case of 6. I presume it was a kind of unexpected bottle fermentation, maybe initiated by too much heat during the transport, transport too soon after bottling or some too hot cellaring.
RR- The bubbles you've described are from nitrogen. As bottles go down the bottling line they are sparged with nitrogen gas to force out any oxygen. The bottle is then filled with wine through a filler.

In the process the gas and wine is slooshed around a fair bit and you can actually see the fine bubbles in the wine as it goes through the process. Once the cork goes in, which is about 1/2 a second later, the gas is more or less frozen in that state. It does settle down in bottle, but when you open it, out come the little fine bubbles. They should be gone with a decant, a shake, a pour or really any agitation that forces the suspended nitrogen out.

The longer the bottle is aged the more of that nitrogen works its way into the head and out of the wine. That's why you don't see as much in older wines, and that's one reason why wineries don't release wines right after bottling.

Bubbles that stay longer than a few seconds are from something else totally. Usually it's secondary, or more correctly continuing fermentation in the bottle. This is caused by having a wine that either has residual sugar or has not finished malolactic fermentation.

If the winemaker does not filter in those circumstances and/or does not add enough sulfur to kill any yeast or bacteria present the wine will start fermenting again, or resume/continue malolactic fermentation. In that case CO2 will be a bi-product and will be absorbed by the wine. This usually ruins the wine as it introduces a slew of off flavors. Heat will make this process go faster, but it will happen at any temperature above the 55-57 degrees that wine should be stored at.

There are some wines, Mosel Rieslings as noted, that are traditionally bottled with a small amount of spritz. They normally get this in tank or barrel though and not in bottle.
quote:
Originally posted by Stefania Wine:
RR- The bubbles you've described are from nitrogen. As bottles go down the bottling line they are sparged with nitrogen gas to force out any oxygen. The bottle is then filled with wine through a filler.

In the process the gas and wine is slooshed around a fair bit and you can actually see the fine bubbles in the wine as it goes through the process. Once the cork goes in, which is about 1/2 a second later, the gas is more or less frozen in that state. It does settle down in bottle, but when you open it, out come the little fine bubbles. They should be gone with a decant, a shake, a pour or really any agitation that forces the suspended nitrogen out.

The longer the bottle is aged the more of that nitrogen works its way into the head and out of the wine. That's why you don't see as much in older wines, and that's one reason why wineries don't release wines right after bottling.

Bubbles that stay longer than a few seconds are from something else totally. Usually it's secondary, or more correctly continuing fermentation in the bottle. This is caused by having a wine that either has residual sugar or has not finished malolactic fermentation.

If the winemaker does not filter in those circumstances and/or does not add enough sulfur to kill any yeast or bacteria present the wine will start fermenting again, or resume/continue malolactic fermentation. In that case CO2 will be a bi-product and will be absorbed by the wine. This usually ruins the wine as it introduces a slew of off flavors. Heat will make this process go faster, but it will happen at any temperature above the 55-57 degrees that wine should be stored at.

There are some wines, Mosel Rieslings as noted, that are traditionally bottled with a small amount of spritz. They normally get this in tank or barrel though and not in bottle.

Paul, you are the man! I love reading the science of wines.
quote:
Originally posted by Roentgen Ray:
...and I am not talking about my Champagne. Try this experiment yourself. Uncork a bottle, pour some wine out to the bottom of the shoulder, put your hand over the bottle's opening, and then shake. I bet there you wine will get a head of bubbles, to steal beer lingo. For the longest time I assumed this was because I am at an altitude of 4240ft, and that it was dissolved air from the winery that bubbled out because of lower atmospheric pressure where I live. I made this assumption because most (not all) wineries are closer to sea level than me. Then, recently, on a trip to NYC, I did the same thing, and...bubbles! So what are these bubbles, is it dissolved hydrogen sulfide gas? I have noticed that older wines have fewer bubbles. Maybe it is dissolved CO2 left over from fermentation. And, of coarse there is the occasional infected bottle with gas forming organisms. And, yes, some is due to elevation changes. Any insight to my bubble quandry?


Isn't this the "Mollydooker Shake?"
So...The Dooker Shake.

Wine contains acids, in fact it is pretty acidic compared to most foods we consume. Acid is measured in pH, the lower the pH number the higher the acid. Most wine is between 3.3 and 3.7. Most tomatoes are 4.0-4.8, beer 4.0-4.5, lemons are 2.3-2.7, meats are over 6.0, carbs usually over 5.0.

Acid acts as a natural preservative in foods. The more acidic a food (low pH) the harder it is for bacteria, yeast or other organisms to grow. This is the idea of ceviche or squeezing a lemon on raw food. The acid will 'kill' any bad things on the protein.

Below 3.0 pH most of the things that will attack a wine will be killed by the natural acidity, but above 3.0 pH the risk of an infection in the wine increases. At right around 4.0 pH all of the yeasts and bacteria we worry about in winemaking will survive.

So what nature has forgotten we have to stuff with Potassium Metabisulfite, or as we usually call it sulfur. The sulfur will protect the wine from bacteria. 30+ years ago UC Davis developed a sliding scale that winemakers everywhere (except strangely it would seem in Luxembourg) use. The lower the pH the less sulfur you have to add to kill off the bacteria. The higher the pH the more you have to add to get the same effect.

The amounts are small. At 3.4 pH you need about 30 Part Per Million of sulfur (30ppm) at 4.0 pH you need about 80ppm. So in a bottle of wine it's a difference of fractions of a gram. Still the effect on the wine is dramatic. At 30ppm the sulfur is really undetectable. At 80ppm it's very dramatic. You don't smell burnt matches, that's a different sulfite, but what you do get is a sickly sweet, sharp or chalky smell.

There's a whole lot of chemistry here I'm not going to cover, including exactly what the sulfur level is (we measure free sulfur and total sulfur separately for instance) but basically the higher the pH the more sulfur you need and the more the wine is going to smell and taste of sulfur.

Sulfur though is easy to get rid of in a wine. Sulfur bonds with oxygen and the sensory impact dissipates quickly. That's one reason we try to limit oxygen contact inside the winery. We can keep total sulfur down and our additions low buy not introducing oxygen to the wine.

The Mollydooker shake is a way to get around this effect. That wine has a high pH (probably over 4.0) and so has to be bottled with a high sulfur level. To most people that results in an unpleasant wine. Especially when you first open the bottle. The idea of the shake is to introduce oxygen to the wine quickly and lessen the impact of the sulfur through the molecular bonding taking place. A little oxygen and a few shakes and the sulfur drops to a level that is not so offensive.

This is already super long but I wrote a blog about it here if you'd like to read further:

See http://stefaniawine.com/?p=495
Great explanations. I assure you that even in Luxembourg adding sulfur is practiced ;-)

I undestand that wines with high acidity (low ph) need less sulfur to be added. Would that mean that wines from cold climate regions (say Chablis, or German Mosel) need less sulfur than wines from the Provence, for instance? What are the figures saying about ph-levels in cold climate regions, from an amateurish point of view i think ph levels are lower in cold climate? Maybe the impression on the palate (noticable acidity) is misleading and cold climate wines in fact dont have a lower ph?
Generally yes - wines from cooler climates have lower pH's and need less sulfur. pH is correctable though by adding Tartaric Acid. It's supposed to be illegal in France, which is not the same thing as saying it doesn't happen.

Some grapes, like Cab Franc, have inherent pH issues and pH can rise very quickly even without warmth. We harvest Cab Franc last November 7th that was 21 Brix and 4.10 pH. Usually with 21 Brix you'd expect a pH of 3.3 or so and with a pH of 4.10 you might think Brix was over 28. From a Cab Sauvignon vineyard 2 miles away we harvest on October 9th at 23.4 Brix and 3.55 pH. Both sites would be considered 'moderate', with about 2800 degree days or the same as Bordeaux.

Sulfur additions are a tricky business. The best piece of equipment we've bought is a sulfur tester that gives Free and Total sulfur. We did a bunch of experimenting to find out how much is lost in the process of adding sulfur and really feel like now we have it dialed in really good.

I've had a lot of California Pinot's in particular that have gone spritzy in the bottle, a sure sign the winemaker left residual sugar and didn't have the pH/Sulfur ratio right.
quote:
Originally posted by PD2K:
quote:
Originally posted by Roentgen Ray:
...and I am not talking about my Champagne. Try this experiment yourself. Uncork a bottle, pour some wine out to the bottom of the shoulder, put your hand over the bottle's opening, and then shake. I bet there you wine will get a head of bubbles, to steal beer lingo. For the longest time I assumed this was because I am at an altitude of 4240ft, and that it was dissolved air from the winery that bubbled out because of lower atmospheric pressure where I live. I made this assumption because most (not all) wineries are closer to sea level than me. Then, recently, on a trip to NYC, I did the same thing, and...bubbles! So what are these bubbles, is it dissolved hydrogen sulfide gas? I have noticed that older wines have fewer bubbles. Maybe it is dissolved CO2 left over from fermentation. And, of coarse there is the occasional infected bottle with gas forming organisms. And, yes, some is due to elevation changes. Any insight to my bubble quandry?


Isn't this the "Mollydooker Shake?"


Yes!

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