Black Grapes

[Hazelemere]

too many variables

 

[David Violante]

The opportunities for learning continue… So I have 3 demijohns, and one each 3-gallon and 5-gallon carboy of this wine. The demis seem to be doing ok, as does the 3-gallon. Two weeks ago I looked at them all and the 5-gallon had small bubbles going and I thought, MLF? Odd given the SO2 routine but ok.

Then I looked a few days ago and I doubt it’s MLF. I’m thinking Brettanomyces. Below are pics of the top of the wine and microscopy. No idea how, but here we are. I clean and sanitize well, and sparge headspace with nitrogen. So, I double dosed with SO2 and added Bactiless 1g/gallon, and dropped the pH from 3.7 to 3.4. The wine tastes ok and there are no off flavors or smells (from the middle of the carboy).

I have three questions: 1) does this seem like enough treatment, 2) what’s the best way to clean and sanitize the items that have been in contact with the wine (plastic sampler and cylinder, silicone bung) so as not to contaminate anything else, 3) should I prophylactically treat the remaining wine from this lot?

 

[wood1954]

If it was Brett it would smell really bad. I had a batch I thought was Brett due to the smell and sent it to a lab for testing, it came back negative. Since then I’ve learned it’s pretty hard for labs to get Brett to grow so the result was probably inconclusive. I dumped that batch and now I keep a chitosan product on hand because it might kill the Brett yeast, luckily I haven’t had to use it.
Daniel Pambianchi’s book Modern home winemaking is a great resource for so2 management. Good luck, nice micro photo. Almost forgot, acetobacteria are usually rod shaped your photo looks like yeast an awful lot for something is done fermenting.

 

[David Violante]

Almost forgot, acetobacteria are usually rod shaped your photo looks like yeast an awful lot for something is done fermenting.

Thank you for sending this over, it got me thinking to check out the UCDavis site for wine microbiology. https://wineserver.ucdavis.edu/industry-info/enology/wine-microbiology/yeast-mold

You’re right, that it looks like a lot of yeast cells and not necessarily rod shaped cells. They also look like they’re budding off the ends and don’t appear in chains. I don’t have the equipment to do a gram negative stain but I might be able to borrow some (bacteria versus yeast).

Here’s what the site says about the umbrella classification Dekera, under which Brett falls: “The vegetative cells are ogival in shape; which results due to repeated polar budding characteristics. In older cultures maintained in laboratories, populations appear elongated. Spherical, ellipsoidal and cylindrical cells have also been reported. Chains may also be observed and this is due to incomplete separation of the daughter cells. Cells vary in size.“

You can also see what you want to see, or are inclined to see. No, I don’t want to see Brett, I hope it’s something far less nefarious.

The main reason I thought Brett in the first place was the signs of fermentation well after it was done, appearing as MLF, the coating on the top, and the presence of bubble shaped formations on the outside ring. What I have NOT smelled, are any of the things that come with Brett. No bandaid, no barnyard, no horse sweat.

UCDavis suggests a strong dose of SO2 and lower pH. I’ve also used Bactiless and isolated the things I used with the carboy, just in case.