Sulphur smell and flavour in wine

So what causes it?

My wife and I had an Ontario chardonnay with our supper tonight. It was quite nice, but there was a note of sulphur (like struck wooden matches) on the nose and in the mouth. With time it increased, to the point that it obliterated everything else.

I have noticed this with other wines as well, in particular a Hamilton Rusell Chardonna from South Africa that I bought a number of years ago.

I have always thought that this had something to do with oak barrels.

Can someone explain?

Poor winemaking would be my guess. Sulphur dioxide is added to wine to prevent oxidation and to kill off any remaining yeasts or bacteria that affects the quality of the wine. Using too much will give off aromas and flavors.

I've seen this many times, but the sulphur usually blows off with time in the glass. I don't remember an occasion when it intensified.

Poor winemaking would be my guess. Sulphur dioxide is added to wine to prevent oxidation and to kill off any remaining yeasts or bacteria that affects the quality of the wine. Using too much will give off aromas and flavors.

I've seen this many times, but the sulphur usually blows off with time in the glass. I don't remember an occasion when it intensified.

Yes, as Bucko says, it blows off.

The cause isn't always poor winemaking. J. J. Prum wines, for instance, aren't the product of poor winemaking, but the sulphur dioxide in these excellent German Rieslings when they are young is enough to burn your eyes (but even with them, time in decanter or glass eventually solves the problem).

The fact that Bruce says it intensified rather than dissipated points to a another possibility, although the smell would be worse than mere sulfurous.

So hard to diagnose over the Internet.

So what causes it?

My wife and I had an Ontario chardonnay with our supper tonight. It was quite nice, but there was a note of sulphur (like struck wooden matches) on the nose and in the mouth. With time it increased, to the point that it obliterated everything else.

I have noticed this with other wines as well, in particular a Hamilton Rusell Chardonna from South Africa that I bought a number of years ago.

I have always thought that this had something to do with oak barrels.

Can someone explain?

This is from too much sulfur dioxide (SO2) in the wine. Sulfur dioxide in the form of potassium metabisulfite is added to wines as a sterilizing and preservative agent (kills bad yeasts and other micro-organisms) and to prevent oxidation. The metabisulfite breaks down when it comes on contact with the wine's acids to release SO2. Most dry wines are finished at about 20-40 ppm. Wines with RS are finished around 80-100. I believe the odor threshold is about 120ppm. However, it is also common practice to burn a sulfur wick in oak barrels to sterilize the barrel before filling with wine. If this was an oak-aged Chardonnay, that could be the source of the excess levels of SO2. Over time, the levels will go down, as Clint points out. If you have more of this wine, I'd suggest cellaring it for a few years or returning it as undrinkable. As far as the odor increase over time as the bottle was opened, perhaps the bottle was chilled at opening and more SO2 was released as it warmed up?

So what causes it?

My wife and I had an Ontario chardonnay with our supper tonight. It was quite nice, but there was a note of sulphur (like struck wooden matches) on the nose and in the mouth. With time it increased, to the point that it obliterated everything else.

I have noticed this with other wines as well, in particular a Hamilton Rusell Chardonna from South Africa that I bought a number of years ago.

I have always thought that this had something to do with oak barrels.

Can someone explain?

This is from too much sulfur dioxide (SO2) in the wine. Sulfur dioxide in the form of potassium metabisulfite is added to wines as a sterilizing and preservative agent (kills bad yeasts and other micro-organisms) and to prevent oxidation. The metabisulfite breaks down when it comes on contact with the wine's acids to release SO2. Most dry wines are finished at about 20-40 ppm. Wines with RS are finished around 80-100. I believe the odor threshold is about 120ppm. However, it is also common practice to burn a sulfur wick in oak barrels to sterilize the barrel before filling with wine. If this was an oak-aged Chardonnay, that could be the source of the excess levels of SO2. Over time, the levels will go down, as Clint points out. If you have more of this wine, I'd suggest cellaring it for a few years or returning it as undrinkable. As far as the odor increase over time as the bottle was opened, perhaps the bottle was chilled at opening and more SO2 was released as it warmed up?

The possibility of chilling and warming is a good one.

Another possibility would be connected if the Chardonnay was a stainless steel version (was it?). In that case, it could be reductive. The built-up intensity could support that possibility.

Reduction occurs when sulfurous compounds take over when the wine is starved of any oxygen.

Simple reduction can be aerated, but the end point of mercaptan needs a copper sulfate treatment.

Howie--most commercial wineries inject SO2 as a liquid gas. Metabisulfite powder is unstable--breaks down easily and makes it hard to keep accurate measurements to treat large volumes of wine.

...Another possibility would be connected if the Chardonnay was a stainless steel version (was it?). In that case, it could be reductive. The built-up intensity could support that possibility.

Reduction occurs when sulfurous compounds take over when the wine is starved of any oxygen.

Simple reduction can be aerated, but the end point of mercaptan needs a copper sulfate treatment.

Howie--most commercial wineries inject SO2 as a liquid gas. Metabisulfite powder is unstable--breaks down easily and makes it hard to keep accurate measurements to treat large volumes of wine.

Thanks for the SO2 liquid gas correction. Speaking from experience (my '04 Cab Franc went through reduction due to a lack of adding enough yeast nutrient - used an unfamiliar yeast strain) reduction produces hydrogen sulfide (H2S) which is the rotten egg odor, not the burnt match odor. These are quite different. H2S, in the presence of wine compounds, will, over time produce mercaptans, which are highly aromatic compounds. In fact, natural gas is odorless and mercaptans are added to it so that gas leaks can be detected.

...Another possibility would be connected if the Chardonnay was a stainless steel version (was it?). In that case, it could be reductive. The built-up intensity could support that possibility.

Reduction occurs when sulfurous compounds take over when the wine is starved of any oxygen.

Simple reduction can be aerated, but the end point of mercaptan needs a copper sulfate treatment.

Howie--most commercial wineries inject SO2 as a liquid gas. Metabisulfite powder is unstable--breaks down easily and makes it hard to keep accurate measurements to treat large volumes of wine.

Thanks for the SO2 liquid gas correction. Speaking from experience (my '04 Cab Franc went through reduction due to a lack of adding enough yeast nutrient - used an unfamiliar yeast strain) reduction produces hydrogen sulfide (H2S) which is the rotten egg odor, not the burnt match odor. These are quite different. H2S, in the presence of wine compounds, will, over time produce mercaptans, which are highly aromatic compounds. In fact, natural gas is odorless and mercaptans are added to it so that gas leaks can be detected.

Howie,

That's why earlier I posted that it's hard to diagnose over the Internet. What someone else describes isn't always what it is.

H2S is a reductive measure and rotten egg is one descriptor of reduction, but there are a host of aromas associated with various stages of reduction. Jamie Goode has done some work on this situation. Sulfurous as in matches, burnt rubber, cabbage, onions and other alium, and on and on...

...Another possibility would be connected if the Chardonnay was a stainless steel version (was it?). In that case, it could be reductive. The built-up intensity could support that possibility.

Reduction occurs when sulfurous compounds take over when the wine is starved of any oxygen.

Simple reduction can be aerated, but the end point of mercaptan needs a copper sulfate treatment.

Howie--most commercial wineries inject SO2 as a liquid gas. Metabisulfite powder is unstable--breaks down easily and makes it hard to keep accurate measurements to treat large volumes of wine.

Thanks for the SO2 liquid gas correction. Speaking from experience (my '04 Cab Franc went through reduction due to a lack of adding enough yeast nutrient - used an unfamiliar yeast strain) reduction produces hydrogen sulfide (H2S) which is the rotten egg odor, not the burnt match odor. These are quite different. H2S, in the presence of wine compounds, will, over time produce mercaptans, which are highly aromatic compounds. In fact, natural gas is odorless and mercaptans are added to it so that gas leaks can be detected.

Howie, if it's any comfort, you weren't necessarily incorrect. In own my small experience with commercial wineries, the use of SO2 as liquid gas happens only at large wineries - at least larger than most of the ones in the region with which I'm most familiar, which is the Sierra Foothills in California. At medium sized wineries (I'm talking up through, say, 10,000 case annual production and wine volumes of up to 5,000 gallons), potassium metabisulfite is the preferred method for making SO2 additions because it's easiest to deal with. As Thomas points out, K2S2O5 breaks down over time but that's easily dealt with keeping a fresh supply.

I'm with you on on SO2 being the likely issue here, too. The orginal poster was pretty clear on this being "like struck wooden matches" and that says SO2 to me - it's a distinctly different odor than anything reductive and one which most people know and would not mistake for any of the reductive possibilities. It is unusual, as others have said here, though, that it increased with time. That I can't account for unless it's because the wine warmed up during the meal.

So what causes it?

My wife and I had an Ontario chardonnay with our supper tonight. It was quite nice, but there was a note of sulphur (like struck wooden matches) on the nose and in the mouth. With time it increased, to the point that it obliterated everything else.

I have noticed this with other wines as well, in particular a Hamilton Rusell Chardonna from South Africa that I bought a number of years ago.

I have always thought that this had something to do with oak barrels.

Can someone explain?

Another possibility is that Bruce's sensitivity to the sulphur dioxide (that's what it has to be) increased as he smelled the wine. I say this because I'm especially sensitive to SO2 and find that with young white wines I often want to cough on the second sniff if not on the first.

...Another possibility would be connected if the Chardonnay was a stainless steel version (was it?). In that case, it could be reductive. The built-up intensity could support that possibility.

Reduction occurs when sulfurous compounds take over when the wine is starved of any oxygen.

Simple reduction can be aerated, but the end point of mercaptan needs a copper sulfate treatment.

Howie--most commercial wineries inject SO2 as a liquid gas. Metabisulfite powder is unstable--breaks down easily and makes it hard to keep accurate measurements to treat large volumes of wine.

Thanks for the SO2 liquid gas correction. Speaking from experience (my '04 Cab Franc went through reduction due to a lack of adding enough yeast nutrient - used an unfamiliar yeast strain) reduction produces hydrogen sulfide (H2S) which is the rotten egg odor, not the burnt match odor. These are quite different. H2S, in the presence of wine compounds, will, over time produce mercaptans, which are highly aromatic compounds. In fact, natural gas is odorless and mercaptans are added to it so that gas leaks can be detected.

Howie, if it's any comfort, you weren't necessarily incorrect. In own my small experience with commercial wineries, the use of SO2 as liquid gas happens only at large wineries - at least larger than most of the ones in the region with which I'm most familiar, which is the Sierra Foothills in California. At medium sized wineries (I'm talking up through, say, 10,000 case annual production and wine volumes of up to 5,000 gallons), potassium metabisulfite is the preferred method for making SO2 additions because it's easiest to deal with. As Thomas points out, K2S2O5 breaks down over time but that's easily dealt with keeping a fresh supply.

I'm with you on on SO2 being the likely issue here, too. The orginal poster was pretty clear on this being "like struck wooden matches" and that says SO2 to me - it's a distinctly different odor than anything reductive and one which most people know and would not mistake for any of the reductive possibilities. It is unusual, as others have said here, though, that it increased with time. That I can't account for unless it's because the wine warmed up during the meal.

I guess I should also point out that over use of SO2 can--and does--lead to reduction.

Thanks for all the helpful input, comments and thoughts guys. I am afraid I can't access this site from work, so that is why I have been absent from the conversation.

By way of background, the wine in question is a Flat Rock Cellars Chardonnay 2004, from Ontario's Niagara Penninsula.

I bought three or four a while ago and loved the few I have had, until this rather odd, and overwhelming, example.

And yes, the wine was moved from my wine fridge to the kitchen fridge and then brought out when we sat down to supper, so it would have warmed gradually while sitting on the table.

Thanks for all the input.