Corks Don't Breathe

[gamble]

This was from a winemakers blog from a real nice Michigan winery, I did not know:

"Contrary to popular belief corks don’t “breathe.” According to Dr. Paulo Lopes and his studies on wine closures at the University of Bordeaux a natural cork is made of 80-90% air. It is the oxygen in the cork that is gradually released into the wine, usually over the first three years in bottle."

 

[Boatboy24]

Who knew? I haven't heard that one before.

 

[sour_grapes]

Here is one of his papers, if you want to check out the original source. https://www.researchgate.net/profil..._Qualities/links/576eaea108ae0b3a3b79cc49.pdf

 

[balatonwine]

I also read this at:

https://www.wine-searcher.com/m/2018/01/putting-a-cork-in-the-oxidation-question

But to me these studies are all the wrong track and method, because they seem all so indirect and correlation based. And assumes a lot that we understand everything how wine reactions to O2 over time.... which we probably do not.

Personally, I would design a radioactive tracer experiment. Bottles placed into a sealed, known external environment that is radioactive tagged. If O2 moves in at first, but then is reduced, or if from the cork only, this should be easy to demonstrate by the resulting isotopes decay results inside and outside the bottle over time.

 

[ibglowin]

Any volunteers to help @balatonwine pull samples? Anyone? Bueller? ....... Bueller?

Personally, I would design a radioactive tracer experiment. Bottles placed into a sealed, known external environment that is radioactive tagged. If O2 moves in at first, but then is reduced, or if from the cork only, this should be easy to demonstrate by the resulting isotopes decay results inside and outside the bottle over time.

 

[stickman]

I looked at that research paper and it doesn't appear to suggest that corks don't breath. They are just suggesting that the high variation of oxygen transfer rates reported for natural cork, is related to the raw cork thickness, which affects the cork cell structure, and internal volume. The logarithmic graph that is presented for oxygen ingress vs. time indicates that the oxygen ingress is high initially, then tapers off to a lower consistent continuous rate later in life. There have been studies previously conducted by others, that also suggested that most of the oxygen came from inside the cork, but they didn't analyze the data with respect to raw cork thickness etc.

This type of information with so many details reinforces why winemakers tend to stick to what has worked for them in the past.

I noticed there is no mention of the common practice of gassing corks with SO2; a fresh bag of corks from a supplier that uses SO2 (mine from Scott Labs smell like SO2 when opened the first time), probably contain a different amount of internal oxygen. I'm not suggesting that this is a big issue to worry about, all of us have bottled wine with corks not packaged with SO2, I don't even know if there is a significant difference either way, but just pointing out that when doing research, details like this have to be reviewed.

I prefer doing my research by tasting........

 

[Redbird1]

I looked at that research paper and it doesn't appear to suggest that corks don't breath. They are just suggesting that the high variation of oxygen transfer rates reported for natural cork, is related to the raw cork thickness, which affects the cork cell structure, and internal volume. The logarithmic graph that is presented for oxygen ingress vs. time indicates that the oxygen ingress is high initially, then tapers off to a lower consistent continuous rate later in life. There have been studies previously conducted by others, that also suggested that most of the oxygen came from inside the cork, but they didn't analyze the data with respect to raw cork thickness etc.

This type of information with so many details reinforces why winemakers tend to stick to what has worked for them in the past.

I noticed there is no mention of the common practice of gassing corks with SO2; a fresh bag of corks from a supplier that uses SO2 (mine from Scott Labs smell like SO2 when opened the first time), probably contain a different amount of internal oxygen. I'm not suggesting that this is a big issue to worry about, all of us have bottled wine with corks not packaged with SO2, I don't even know if there is a significant difference either way, but just pointing out that when doing research, details like this have to be reviewed.

I prefer doing my research by tasting........

Interesting angle. There are so many variables that need to be considered.

I think I've stated it elsewhere before, but a wine version of the Brulosopher would be great, but the long timeframes needed for wine vs. beer make it very, very difficult.

 

[sour_grapes]

Personally, I would design a radioactive tracer experiment. Bottles placed into a sealed, known external environment that is radioactive tagged. If O2 moves in at first, but then is reduced, or if from the cork only, this should be easy to demonstrate by the resulting isotopes decay results inside and outside the bottle over time.

Unfortunately, there are no suitable O isotopes. The longest-lived, unstable O isotope has a half-life of 2 minutes.

 

[ibglowin]

Stop by sometime I will get you some Tritium and some proper PPE.....

If you get contaminated you get to drink all the beer you want.

Unfortunately, there are no suitable O isotopes. The longest-lived, unstable O isotope has a half-life of 2 minutes.

 

[balatonwine]

Unfortunately, there are no suitable O isotopes. The longest-lived, unstable O isotope has a half-life of 2 minutes.

I did not actually say to use radioactive oxygen isotopes, even if O2 is the element of "concern" that affects wine. Put extra C14 in CO2 in the surrounding case. It it enters the bottle, corks "breath". The amount of O2 transgress, I would argue, can then be accurately and directly calculated using side experiments that measure the CO2/O2 transfer rate ratio.

Suggested radioisotope as was merely thinking it would be easier to measure the difference.

One can even bottle an inert liquid (no interaction on anything that enters) in an inert gas (no oxygen at all) environment to improve measurement ability of what enters the bottle, but of course that adds a question mark about what affect wine itself has on cork permeability.

One can also imagine, if wanting to use a tagged O, using instead a stable O18 isotope on the outside, similar as done in doubly labeled water experiments, if the rate of O18 ingress was sufficient to measure over time (but with a 100 year experiment, that should be enough time).

Lots of options, which I think may be improvements on the current line of research. Because, subtracting measurable isotope cork sources, if there is more in the inside than that, it could only have come from the outside. If not, then corks don't breath.

Of course all just a concept. Would all have to be worked out on paper for practicality.

 

[balatonwine]

Any volunteers to help @balatonwine pull samples? Anyone? Bueller? ....... Bueller?

The concentrations of radioisotopes would be low, it would not be a problem. It is not improbable, or even unlikely, you now have more exposure from the Radon in your home, than from this experiment.

 

[Yettiman]

Umm, sorry, I just do not believe this.

I do not degass my reds, I cork and allow them to degass naturally over time. If the corks did not allow the wine to breathe the wine would still be fizzy a year later, which they are not, so, IMHO, the CO2 is venting out through the cork, is this not breathing?

 

[Johnd]

Umm, sorry, I just do not believe this.

I do not degass my reds, I cork and allow them to degass naturally over time. If the corks did not allow the wine to breathe the wine would still be fizzy a year later, which they are not, so, IMHO, the CO2 is venting out through the cork, is this not breathing?

I too believe that corks breathe. I, however, do not believe that bottling fizzy wine will degas through the cork. I’m just flat out calling BS on that statement.

 

[stickman]

If you plan on allowing your wines to degas through the cork, you'll be waiting a long time. The amount of CO2 gas in wine post fermentation is typically on the order of 2000 ppm (Peynaud, 1987). The typical recommended ranges of co2 pre-bottling are: 200–500 ppm for aged red wines and 500–1800 ppm for lighter reds and white wines (Müller-Späth, 1982; Boulton et al., 1996). The co2 loss through a cork depends on cork quality etc., but is on the order of 100 ppm for every 2.5 years of aging at typical cellar temperatures (NomaSense Technical Letter 06).

 

[Johnd]

If you plan on allowing your wines to degas through the cork, you'll be waiting a long time. The amount of CO2 gas in wine post fermentation is typically on the order of 2000 ppm (Peynaud, 1987). The typical recommended ranges of co2 pre-bottling are: 200–500 ppm for aged red wines and 500–1800 ppm for lighter reds and white wines (Müller-Späth, 1982; Boulton et al., 1996). The co2 loss through a cork depends on cork quality etc., but is on the order of 100 ppm for every 2.5 years of aging at typical cellar temperatures (NomaSense Technical Letter 06).

So for a cab bottled gassy at 2000 ppm to get down to recommended pre-bottling high of 500, would require a loss of 1500 ppm of CO2. At 100 ppm loss / 2.5 years, it would take 37.5 years just to get to pre-bottling high levels.

The light and white wine, best case scenario, to get from 2000 to 1800 (you sure 1800 is the number?) is 5 years, and that’s just to reach the pre-bottling high. Substantial time periods for sure..........

 

[stickman]

So for a cab bottled gassy at 2000 ppm to get down to recommended pre-bottling high of 500, would require a loss of 1500 ppm of CO2. At 100 ppm loss / 2.5 years, it would take 37.5 years just to get to pre-bottling high levels.

The light and white wine, best case scenario, to get from 2000 to 1800 (you sure 1800 is the number?) is 5 years, and that’s just to reach the pre-bottling high. Substantial time periods for sure..........

Those co2 ranges are just textbook values for comparison. I would say half of the co2 might be lost during normal racking and transferring, so the wine might be starting at 1000 ppm, but this is still a lot of gas. The perception of acidity is increased with increasing levels of co2, so a sweet white wine could handle more co2 than a dry white, but it still has to be balanced with acidity including the influence of co2 on taste.

For a tannic red you have to get down to the low co2 range, due to the additive effect of acidity and co2 on the perception of tannin.

 

[bstnh1]

If, as the research suggests, oxygen leaves the cork over time, then what replaces it? Seems to me that air (oxygen) from outside would have to fill the vacuum left by the exiting oxygen. In other words, one way or another, corks do breathe.

 

[drainsurgeon]

Why are you supposed to wait a few days before laying your bottles down after bottling? Isn't that to let the compressed air to vent through the cork?

 

[winojoe]

Corks manufacturers provide specifications on their corks. One of the specs is Oxygen Transfer Rate (OTR) ..guess we can all figure out what this acronym suggests.

Here is an interesting article about OTR I read some time ago:
https://www.practicalwinery.com/winter2011/closure3.htm

 

[ibglowin]

No. It’s to allow the compressed cork to return to its normal shape after being inserted.

Why are you supposed to wait a few days before laying your bottles down after bottling? Isn't that to let the compressed air to vent through the cork?