Suds-like slick on wine pour

[4score]

Opened a friend's wine and my wife and I noticed this soap-like oil slick on the surface of the wine once poured. It was a Cab Franc from a few years ago. A few swirls and it's gone but I just wanted to get the consensus thoughts on this. The wine smelled and tasted great, but it's a little disconcerting on the pour.

 

[NorCal]

Soap residue In the glass?

 

[4score]

Hmmmm. I guess it could be, but I noticed it on the 2nd round of pours. If residue on the glass, I would have thought it wouldn't be there on the 2nd round of pours.

 

[Boatboy24]

I was thinking 'dust' from the cork, but seeing it on the second pour would make that unlikely.

 

[Rice_Guy]

Best guess is a dirty bottle
oil/ fat would not mix in
protein would not mix away
complex cell structures/ bacteria or mold would not mix in
sugars and mineral tend to be heavy and sink, have solubility rate which we can watch, could have surface tension and float

this leaves #3 sugar/ carbohydrates, ,, #2 salts/ mineral material, ,,, #1 a complex that formed in the glass between a soap ingredient and a wine ingredient
if it will quickly mix in it should have dissolved in the bottle so the guess is #1 but I can’t suggest what chemical/ complex it is

an extremely good puzzle

 

[winemaker81]

Clean the glasses really well and try again -- this may determine if there's something in the glass, not the bottle. E.g., the dish soap you use?

At least the wine tastes & smells good.

 

[stickman]

Looks like a combination of CO2 and protein.

 

[Rice_Guy]

Looks like a combination of CO2 and protein.

CO2 is a good guess since it would disappear.
proteins are interesting in that a native protein can make a transparent solution and are good at stabilizing foams (ex gluten in bread), and a denatured protein (ex cooked egg white) could make a white froth or rigid bubble in bread, ,,, what would be the source of a native protein in a 12% alcohol based solvent?

 

[stickman]

My comment was just an observation. Most of the time with red wine the initial proteins are removed by tannins, but that depends on the amount of tannin available and extracted during the process. It would probably help to know how the wine was made, especially if any fining agents or other potential sources of protein like lysozyme were used.

 

[Rembee]

It is possible that the wine maker may have used egg whites. Egg whites are used for fining, to tame strong tannins, reduce astringency and give the wine a rounder mouthfeel.
That would explain the proteins.

 

[Bossbaby]

Do you know if that wine was filtered? I dont filter my wines yet so I like to mark the bottle when it's the last one I bottle in a batch because of the undisolved sediment at the very bottom. could it be sulfites or even starsan? I would think if it tastes good it's safe to drink, that's how I roll anyway.

 

[4score]

It is possible that the wine maker may have used egg whites. Egg whites are used for fining, to tame strong tannins, reduce astringency and give the wine a rounder mouthfeel.
That would explain the proteins.

I'm asking him if he used any fining agents. Thanks.

 

[4score]

Do you know if that wine was filtered? I dont filter my wines yet so I like to mark the bottle when it's the last one I bottle in a batch because of the undisolved sediment at the very bottom. could it be sulfites or even starsan? I would think if it tastes good it's safe to drink, that's how I roll anyway.

I think he used a SO2 solution to rinse the bottles....I already asked him if he used Starsan.

 

[4score]

I'm asking him if he used any fining agents. Thanks.

He did filter and did not use any fining agents or lysozyme.

 

[Rocktop]

I may be on a wrong tangent, but I wonder what the final sulphite levels were?
I was reading tonight about high pH wine making and it was mentioned wines over 200ppm SO2 can have a soapy finish. Now I assume that may be referring to the finish in the mouth but it caught my eye in the context of this thread.
Just a thought.

RT

 

[Rice_Guy]

@Rocktop metabisulphite is a powder which does float or a while, but is quite soluble.
200 ppm powder in a 200 ml glass of wine represents 0.04 gram of powder
yes soapy is a mouth feel.

It would be interesting to pull a vacuum on this batch to see what the residual gas level is, as with a VacuVin or head space eliminator.