Substance floating on top of wine

[Paulie vino]

Hi everyone, long time lurker first time poster. I have a question I was hoping someone could answer. I opened a gallon jug of Chilean Cabernet Sauvignon that I had made last year from a juice bucket and it's been sitting in the one gallon jug since December undisturbed. When I opened it I saw what looked like round shaped blobs floating on top, very similar in color to the wine. It smells good but I did not taste it. My thought is that it could be oil separating from the wine. It kind of looks how oil does when it floats on water. I attached a picture. Any ideas?

 

[David Violante]

Paulie, it could be a few things, but some further questions would help to answer. Do you know the alcohol content, pH, did you add sulfites, has it happened to anything else you have?

 

[Rice_Guy]

First of all welcome to WMT

Wine is a preservative system so you don’t have to worry about food poisoning. pH under 4.0 with 11% alcohol things with off flavors grow. Add in metabisulphite and no oxygen and it is good for years.
The oil and fat content on cab Sauv. is low so that is not likely unless there was a contaminant in the carboy, ,, Does the stuff feel greasy?. The main risk as David hinted, is air exposure as in a dry air lock or opening to test several times in twelve months without adding meta each time and you have an Acetobacter bacterial infection creating vinegar. This also is a natural food product so you can taste or smell (like a salad dressing). ,,, my impression from the photo is bacterial mat which had marginal oxygen/ is thin. With better oxygen exposure a bacterial mat should get thicker and look white. ,,, again a possible off taste but not toxic.

Another normal case is some residual yeast clumping but this normally sinks, not floats

 

[winemanden]

Welcome. Try mopping it off gently with some clean kitchen towel. I know that's not the answer to your question, but you may be able to easier see what it is.

 

[FlamingoEmporium]

I’m gonna vote for something that didn’t get cleaned out of the jug properly.

 

[ibglowin]

Looks like the start of Mycoderma to me. Dab it with a paper towel make sure it has enough Sulfite in it and perhaps add another dose. I would also spritz the top with your sulfite spray bottle. Make sure you have it stoppered well so no air is getting in. Myco is a yeast infection that needs air to reproduce.

Hi everyone, long time lurker first time poster. I have a question I was hoping someone could answer. I opened a gallon jug of Chilean Cabernet Sauvignon that I had made last year from a juice bucket and it's been sitting in the one gallon jug since December undisturbed. When I opened it I saw what looked like round shaped blobs floating on top, very similar in color to the wine. It smells good but I did not taste it. My thought is that it could be oil separating from the wine. It kind of looks how oil does when it floats on water. I attached a picture. Any ideas?View attachment 87903

 

[Paulie vino]

Thanks for all the replies so far.

The bucket didn't have any information about ph, acid or brix and all I have is a hydrometer which measured 1.022 prior to adding the yeast (it appeared to be fermenting already when I opened it).

I should mention I used a plastic screw top to seal the jug since December and the last metabisulfite does was late November. Maybe the plastic screw top wasn't air tight enough and the sulfites burned off in the past 5 months enough to allow something to grow.

I decided to dab my finger on top and attached a picture of what it looked like. It didn't feel greasy. Doesn't look like the white mold I've seen in other photos. You can also see the type of screw cap on the desk in the background.

I used a paper towel with some sulfite solution to get most of it out and gave it a spray of sulfites to the surface. We'll see what happens . Thanks for the replies

 

[BigDaveK]

I think @ibglowin might be right. I was using the Wayback Machine to read Jack Keller's site. Saw this, remembered your post, so cut and paste:

Flowers of Wine: Small flecks or blooms of white powder or film may appear on the surface of the wine. If left
unchecked, they grow to cover the entire surface and can grow quite thick. They are caused by spoilage yeasts
and/or mycoderma bacteria, and if not caught at first appearance will certainly spoil the wine. If caused by
yeast, they consume alcohol and give off carbon dioxide gas. They eventually turn the wine into colored water.
The wine must be filtered at once to remove the flecks of bloom and then treated with one crushed Campden
tablet per gallon of wine. The saved wine will have suffered some loss of alcohol and may need to be fortified
with added alcohol (brandy works well) or consumed quickly. If caused by the mycoderma bacteria, treat the
same as for a yeast infection. The Campden will probably check it, but the taste may have been ruined. Taste the
wine and then decide if you want to keep it. Bacterial infections usually spoil the wine permanently, but early
treatment may save it.
Prevent the introduction of spoilage yeasts and mycoderma the same way you prevent the introduction of
vinegar yeasts -- by introducing early an aseptic level of sulfites.
Flowers of wine are, of course, expected when using flor sherry yeast. In such a circumstance, there is no way to
know if the flowers are from the flor sherry yeast or a harmful infection. Pre-treating the must with Campden,
however, should eliminate a harmful infection.