How to confirm the wine is corked?

Salut/Hi Eric lee,

le/on Sun, 23 Nov 2003 02:05:23 +0800, tu disais/you said:-

H2S, often caused by sulphur dropping onto the bottom of a barrel, when the sulphur "candle" is burnt in it to sterilise it. However as your Tempranillo isn't oaked that sounds improbable.

This is called "blowing off" and quite often happens with some minor faults.

Doesn't prove anything at all and in general doesn't give much information even if the wine were corked.

or the wine is corked.

No it's not normal and from your description the wine is _definitely_ not corked.

People describe a corked wine smell in many ways, but most often have the words "wet" & "mouldy" associated. So "Wet dog" "wet cardboard" "mouldy cardboard" are all used fairly frequently. A very slightly corked wine may not have much corked smell (at first certainly) but the smell does NOT go away, it gets worse and that's the MOST distinctive characteristic of a corked wine.

Well, you've been pretty lucky, or else you're one of the people like me who are very insensitive to TCA. However, MY perception of a slightly corked wine is that it "isn't showing well", and that's happened to me quite a few times.

Eric, "rotten egg" odors are an indication of the presence of hydrogen sulfide, a "reductive" wine fault that can result from - among other things - malnourished yeast during fermentation or improper handling of the wine when it is on the lees (dead yeast cells). As you observed, the smell of hydrogen sulfide often "blows off" with exposure to air, at least in relatively minor cases. A subtly corked bottle, on the other hand, might be detectable only to those familiar with a given wine as an absence of fruit. Aromas in more extreme examples of corkiness are most often described along the lines of "musty" and/or "damp cardboard". People vary widely in their ability to detect TCA, the chemical responsible for corked bottles but just about everyone can smell hydrogen sulfide. A corked bottle tends to get worse, not better, with air. The rotten egg odors you noticed cannot be called "normal" but your bottle was not likely corked, both because the smell is wrong and because it declined with time - unless you were unfortunate enough to find a bottle that was corked in

- Mark W.

You're right that it's Hydrogen Sulphide, but that would not be caused by a sulphur candle in the barrel; that would give Sulphur Dioxide taint.

The combination of nitrogen deficiency in the must, use of sulphur dioxide before fermentation, and certain types of yeast give H2S taint.

Can be removed by putting a copper coin in the glass.

Why is nitrogen needed in the must? Is it dissolved in the must? And how does its deficiency yield H2S?

Mike

The deficiency is apparently related to certain soils and grape varieties, and one solution is to treat with diammonium phoshate, so I presume the nitrogen is chemically bound rather than dissolved.

Beyond that, I do not know. My source of information is The Oxford Companion to Wine, which says quite a bit more about the issue, but does not directly answer your questions. If you are really keen to find out, this article has a couple of references to scientific journals. Let me know if you want the references.

Salut/Hi Steve Slatcher,

le/on Sun, 23 Nov 2003 17:30:48 +0000, tu disais/you said:-

With respect, I think you ought to read what I said. I _was_ aware that burning sulphur gives sulphur dioxide, and that in fact this is what is intended - to sterilise the barrel. You were probably not aware that sometimes, drops of molten sulphur heated by the combustion of the "candle", can dribble off the bottom and fall to the bottom of the barrel, where the flames go out. This _unconverted_ sulphur can - I repeat - give H2S contamination.

Thanks guys for your help,

After all, that bottle is bad and I'm quite disappointed as wanted to try a young Tampranillo which show varietals characteristic after reading recommendation in wine book by Jancis Robinson. It took me a hard time looking for minimum oak influence copies. As it's cheap and not a mainstream style. Not many merchant willing to carry I guess...

However, I still haven't give up yet, That bottle is a Vina Allbali Tampranillo 2002 from Valdepena, Spain. Not even a Crianza class so I guess it's not wooded at most old wood.

Should I go back and get another bottle or another vintage of the same wine, If not any suggestion? How about Corona by Torres, but it's still age for 6 months in wood which is good enough to be crianza although it's not labelled so. Would I able to taste the fruit unadulterated?

Have found a solution, I have decant it and the sulphur smell has gone, and the fruit come through. The wine is powerful enough to last through the aeration process.

Mike, I suspect that the role of nitrogen in the must is as a nutrient for the yeast. A low level of nitrogen would lead to early death of the yeast, which seems to be one of the primary causes of H2S.

Mark Lipton

OK. Guilty as charged. Though for some reason it weas only on the

Mark, that's right - yeast need a long list of nutrients but the most important ones are oxygen and nitrogen. The need for oxygen is one of the reasons the cap is "punched down" in making reds, although that task is often accomplished these days by pumping the wine over the cap, sometimes even after being aerated. Nitrogen is also often added (usually in the form of diammonium phosphate, as has already been noted), sometimes after lab analysis for nitrogen in the must (there's a technical name for the test that would mean something to you but escapes *me*), sometimes routinely, especially for varieties that are known for producing low-nitrogen musts, like Zinfandel and Syrah.

- Mark W.

It has always been my understanding that yeast did not NEED oxygen as a nutrient, although for reproductive reasons it would prefer its presence. It has also been my understanding that if oxygen were present in sufficient amounts, no alcohol would be produced, only water and CO2.

I have also never heard that "punching down" the cap while making reds was for any other purpose than increasing the contact between the liquid and the skins, thus facilitating the extraction of various substances from the skins.

Vino

Salut/Hi Steve Slatcher,

le/on Mon, 24 Nov 2003 19:03:42 +0000, tu disais/you said:-

It's amazing how often on these NGs one reacts to what one THINKS one reads and not what is actually written. ;-))) That's the main reason I use an offline Newsreader. It enables me to re-read my replies and make sure that I'm - more or less - answering the message!

Alright, thanks for the info about nitrogen, although nobody I know ever has the need to add diammonium phosphate.

Now here is another question for the chem wizes, what about the smell of reduced wine, typical of certain varieties when the must spends too much time in the barrel or the bottle. Mourvedre tends to reduction, syrah does not. Smells faintly like rotten eggs, but not quite, more like burnt rubber. The yeast are the beasties doing this reduction. What is the reaction going on? Which molecule is responsible for the smell?

I ask because this smell is more and more present. Try opening 10 bottles of Domaine Tempier, at least 3 have this smell and require a few hours decanting before it goes away.

It seems to be more present because the new generation of oenologists has been taught that air is some kind of ghastly monster to be avoided at all cost: none is allowed in at any stage of winemaking... everything is done in perfectly anerobic conditions.

Mike

Mike, That's almost certainly the smell of a thiol (mercaptan). These are the organic relatives of H2S, and can be equally noxious. Skunk "perfume" is one such thiol, and the odorant used in natural gas is another. The funny thing about thiols is that at low levels, many people find them pleasant: the odor of freshly brewed coffee is primarily due to a thiol, and many of the "tertiary" aromas of wine are also due to thiols. The coffee odorant (thiophene-2-thiol) smells like burnt rubber at higher concentration, and is often found in wine. Thiols are thought to arise post-fermentation from yeasts during "sur lie" aging:

Hopefully, the pendulum will swing yet again, just as it has on the topic of filtration and fining.

Mark Lipton

Thanks Mark, I knew you would precipitate an answer...

When are you and your better half coming over here to smell some of those reduced wines? ;-)

Mike

Vino, there are multiple reasons for punching down the cap. The most basic, as you say, is to facilitate extraction of goodies from the skins. A second is that a dry cap is a perfect medium for aerobic bacteria, notably acetobacter that want to produce volatile acidity (turn the wine to vinegar, in other words). For that reason it is important to keep the cap moist. The last reason, as I said before, is to provide the yeast oxygen and prevent them from producing hydrogen sulfide.

As for your point about oxygen not being a yeast nutrient, I'm not an expert about exactly how a yeast uses oxygen, I'm only familiar with what goes on from a winemaking perspective. What I know is that if the yeast don't get enough oxygen, they make H2S. Whether that's because they need it for reproduction or because they need it as a nutrient amounts to the same thing for practical purposes. As we all know, oxygen is the enemy of wine once it is fermented but during fermentation it is necessary. In small batches, the exposed area is large compared to the volume of the must and punching down generally introduces the required oxygen. In commercial operations, also as I mentioned before, you get lots of air introduced during what is called "pump over" when wine is pumped from beneath the cap and hosed back on top of it. In some cases when even more aeration is desired, the fermenting wine is actually shot through the air in a special aeration device before being pumped on top of the must! I hope that helps.

- Mark W.

Mike, Mark Lipton would probably better able to answer this question but the layman's version is that the two problems are related - one being just an advanced example of the other. The burnt rubber smell comes from a class of chemicals called mercaptans. A mercaptan molecule is the reductive analog of alcohol, in other words an alcohol molecule with sulfur replacing oxygen - just as hydrogen sulfide (H2S) is the reductive analog of water. Mercaptan is what can result when a H2S problem is not dealt with early; that is why most winemakers prefer prevent H2S formation in the first place (by adding DAP and/or providing the fermenting most with ample oxygen) or or at least deal with it as soon as it is detected. In general, my observation is that this sort of fault is actually much *less* common than in years past but it sounds like your experience is different!

- Mark W.

Yeast use oxygen in a number of ways. I'm not going to get into if it is actually a nutrient or not because I think that's semantics.

First, they use it in the production of Sterol and Fatty acid desaturation. Both of these are important for the survival of the yeast as the alcohol increases. They effect the membrane fluidity and hence the ability of the cell to control the movement of chemicals across the cell wall. I believe this is especially important during the growth phase as half of the Sterols and Fatty acids go to the new cell when budding occurs and can be depleted rapidly.

They also use it in the degradation of some nitrogen compounds. This is the case where DAP will help, because I think most (if not all) yeasts can use DAP without oxygen requiring degradation.

Third, yeast can respirate to create energy. In reality, this doesn't happen much during wine fermentation because yeast don't respirate if there is a high level of sugar (at the beginning of fermentation) even if there is oxygen and respiration is inhibited towards the end of fermentation by a lack of oxygen and the presence of alcohol.

Andy